Wednesday, January 05, 2011

The Tarpaper Shack Principle

Was it just me, or were last Friday’s New Year celebrations a bit short on enthusiasm? The chance to give the smoking wreckage of 2010 a decent burial might have inspired some cheer, except that 2011 seems unlikely to bring anything better. With the price of oil lurching around the $90-something a barrel range, a so-called economic recovery that has been almost entirely confined to press releases, and the electorate slowly waking up to the fact that the only change they can believe in that’s coming from the Obama administration is the kind Rudy Vallee sang about in “Brother, Can You Spare A Dime?” – well, let’s just say that none of this adds up to optimism for the year ahead.

Thus the New Year’s Eve blog post from Chuck Burr at Southern Oregon Permaculture was timely. At a time when plenty of people are still insisting that the whole world can adopt a middle-class lifestyle powered by renewable energy resources, Burr cited hard numbers from a representative case study – his own solar-powered home – to show why high-tech renewables are at most a way station partway down the Long Descent. His argument will be familiar to readers of this blog: the photovoltaic system that powers his home won’t generate enough electricity in its lifetime to both account for the power that goes into making and maintaining it, and provide enough electricity to maintain a modern lifestyle for its end user. Burr went on to suggest, reasonably enough, that using high-tech renewables is still a good idea for now, since it will help cushion the future in which green plants may well turn out to be the most efficient source of primary energy around.

He’s likely right, but there are challenges in the way of even so modest a project. The obvious issue – the fact that the very large number of people closing in on their 99th and last week of unemployment benefits, and the even larger number caught in the stagflationary vise of dwindling wages and soaring bills, aren’t going to be in any position to buy and install expensive photovoltaic systems – is symptomatic of a far more profound and pervasive difficulty.

That difficulty, interestingly enough, was sketched out well in advance in the pages of The Limits to Growth, still the best – and thus, inevitably, the most reviled – map of the future toward which the industrial world is hurtling, eyes closed and pedal to the metal. It’s always fascinated me that in a society that claims to make most of its decisions on the basis of economics, so few people grasped the essentially economic argument at the core of the Limits to Growth analysis. That study did not claim, as so many people still insist it claimed, that the resources on which industrial society depends are going to up and run out one of these days. It proposed, rather, that the real costs of extracting resources and dealing with the consequences of environmental pollution, both of which are driven by economic growth, necessarily increase faster than the rate of economic growth itself, and sooner or later will force industrial civilization to its knees.

Perhaps the most visible signpost along the way to that destination is the point at which a society can no longer provide for its future and pay its current expenses out of existing resources. You know that point has arrived when a society begins neglecting its infrastructure, slashing basic services, discarding those economic sectors that cost too much to maintain, and abandoning those people who lack the political clout to make good a claim on slices of the dwindling pie. Readers here in America who don’t find this description oddly familiar are encouraged to take a good hard look out the nearest window.

The consequences of that logic pose an immense challenge to the more optimistic proposals for dodging the resource crunch at the end of the age of cheap petroleum – the nuclear power plants, high-speed rail networks, immense solar installations in assorted desert countries, and the rest of it. All these would require huge inputs of real wealth – not currency, which can be manufactured at will by central banks, but energy, materials, knowledge, and labor – real wealth – which are a good deal harder to conjure up out of twinkle dust. The Limits to Growth model suggests that underneath the smoke and mirrors of the financial economy lies the awkward fact of a shortfall in real wealth, caused by the need to divert a growing fraction of real wealth to meet the direct and indirect costs of extracting resources, on the one hand, and coping with the impacts of environmental pollution on the other. If that’s what’s going on – and I think a good case could be made for that thesis – then trying to scrape together enough real wealth to cover the cost of these projects simply piles another burden onto an already overloaded economic structure, and if pursued with enough misplaced enthusiasm, could conceivably become the trigger that brings the whole thing crashing down.

Now of course there’s another way to go about preparing for a future of scarce expensive energy, and it’s one of the key strategies of the "green wizardry" I’ve been discussing here iover the last six months or so. The central concept of that strategy might as well be called the Tarpaper Shack Principle: you don’t actually have a resilient energy technology unless you can build it from readily available materials, and put it to work for some useful purpose, while living in the kind of tarpaper shack the last Great Depression made famous. You may well end up living in something like that, you know; a great many people did the last time the industrial economy came unglued, and we are arguably in a much worse position today than in 1930, so looking up some renewable energy technologies that could have been made and used in a 1930s Hooverville may be more than a thought exercise just now.

Finding such technologies may seem like a tall order. It isn’t; there are scores of proven, mature technologies that can be tacked together from scrap, powered by renewable energy sources that cost little or nothing, and contribute mightily to getting the basic tasks of living done more easily, safely, and cheaply. The fireless cooker, the topic of last week’s post here, is one of them, and so is the technology I’d like to introduce this week, the solar box cooker.

It’s hard to think of anything as cheap that accomplishes as much. You can make one out of cardboard, glue, used newspaper, aluminum foil, and a piece of discarded window glass. Placed in direct sunlight, it will easily get up to oven temperatures and cook your meals for free. It can also be used to purify tainted water, sterilize bandages, or do anything else that 300° to 400° F of even heat will do for you.

The solar box cooker also has the not inconsiderable advantage of teaching three of the basic rules of working with solar energy in a way most people grasp intuitively at once. Rule #1 is the greenhouse effect: energy from sunlight that passes through glass and is absorbed by something inside the glass tends to get trapped there, because glass is transparent to visible light but opaque to the infrared wavelengths that radiate out from warm objects. Rule #2 is the thermal mass effect: some materials absorb heat better than others, and if you put something with a high capacity for heat absorption in the presence of a heat source – say, a pot of beef stew in direct sunlight – it will soak up heat that can then be put to work. Rule #3 is the insulation effect: some materials resist the flow of heat better than others, and if you surround your thermal mass with a bunch of insulation, the heat absorbed by the thermal mass will stick around longer and do more work. (Keep these three rules in mind and most of what we’ll be covering in the months just ahead will be a lot easier to follow.)

There are several standard designs of solar box cooker. The simplest looks exactly like what the term suggests, a square or rectangular box – or, more precisely, a box within a box, with insulation between them to form a heat barrier – with a pane of glass on top. A hinged lid covers the glass when the box cooker isn’t in use; it has tinfoil on the underside, so that when you’re ready to use the box, the lid can be propped up at an angle to reflect more sunlight into the box. Yes, you can make one out of cardboard and newspaper in about an hour, and yes, you can then set it out in the sun and cook your dinner with it.

The more complex designs put the glass pane at an angle, to increase the amount of sunlight that gets in, and have more reflecting surfaces for the same reason; the fanciest look like metal flowers or props from 1970s science fiction movies, and you don’t want to make them out of cardboard because they can get hot enough inside to set the cardboard on fire. I’ve seen some very impressive solar box cookers on the fancy end of things, with mirrors that would do justice to a telescope and elegant arrangements to track the sun; they arguably go well beyond anything you’d be able to put together while living in a tarpaper shack, but there’s always the possibility that you might get lucky while combing through the ruins of an abandoned suburban housing development.

Two other developments off the same basic approach are also worth mentioning. The first was invented by one of the patron saints of green wizardry, the redoubtable 19th-century French solar energy pioneer Augustin Mouchot. Tasked by the French government with coming up with solar technologies for the French colony in Algeria – which has a surplus of sun and, at least in Mouchot’s time, a shortage of most other energy sources – Mouchot invented, among other things, a solar cooker for units of the French Foreign Legion stationed there. The device was simplicity itself – a cone of metal, reflective on the inside; a cylindrical steel cooking chamber that went up the centerline of the cone; and a tripod stand. Mouchot’s solar cooker was collapsible, weighed less than forty pounds, and cooked a pot roast to a nice medium rare in under half an hour. It remained standard issue for French troops in North Africa for decades; I have no idea if any examples survive, but it’s 19th century technology, and an enterprising metalworker ought to be able to knock one together fairly easily – even in a tarpaper shack.

The other device I have in mind comes from the other end of the solar cooking spectrum, but it’s as elegant as the Mouchot cooker and even more portable. The Umbroiler was invented by American solar pioneer George Löf and marketed for a while in the 1960s and 1970s. It’s exactly what the name suggests: a sturdy umbrella frame with silver metallized cloth in place of the usual fabric, a grill in place of the handle, and a tripod on what’s normally the top of an umbrella and is the underside of the Umbroiler. It folds up like any other umbrella, but when you open it and point it toward the sun, you can cook anything from fried eggs to hot coffee on the grill. The original version was too expensive to be commercially viable, due mostly to the high cost of metallized fabric back in the 1960s; these days, that has changed, and since any patents have long since expired, a revival of the Umbroiler could make somebody with a sewing machine and some metalworking skills a very functional small business.

By now, I suspect, some of my more skeptical readers will doubtless be jumping up and down, eager to point out that solar cookers aren’t viable everywhere, and only work when the sun’s shining. This is of course true, but it’s also beside the point. Nothing in the appropriate technology toolkit is suited to every context – that’s one of the implications of that word "appropriate," after all – and nothing ever again in human history will provide our species with the kind of instant, context-free torrent of energy we now get from fossil fuels. Once those are gone, the entire approach to technology that’s built on the assumption of abundant, highly concentrated, highly portable energy supplies goes whistling down the wind, and the approaches – in the plural – that will replace it are going to be less convenient, less portable, and less capable of ignoring the rest of the cosmos than what we’re used to.

What that means in practical terms is that the well-equipped kitchen in the tarpaper shack that’s waiting for you a few years down the line will have a solar box cooker, which you can use on sunny days, and a small, efficient stove and fireless cooker, which you can use on cloudy days. It really isn’t that complicated, once you grasp the crucial point that a technology that relies on diffuse renewable energy sources doesn’t work the same way as a technology that relies on concentrated fossil fuels. That’s one of the lessons of the Tarpaper Shack Principle, and it’s also one of the gifts that the solar box cooker in particular has to offer.

Resources

The solar box cooker is one of the few creations of the old appropriate tech movement that hasn’t been allowed to languish in obscurity, largely because of its huge advantages in the Third World. The photocopied pamphlets I got back in the day from Solar Box Cookers Northwest, one of the pioneering organizations in the field, have long since been superseded by websites brimfull of practical information. The best of the lot just now is http://www.solarcooking.org -- click on the link marked "build a solar cooker" and you’ll soon be wallowing in plans I would gladly have given my eye teeth to get hold of thirty years ago.

There are also several very good books on the subject. Beth Halacy and Dan Halacy’s Cooking with the Sun is a little out of date but remains well worth having, not least because of its detailed recipes and cooking instructions. Joseph Radabaugh’s Heaven’s Flame covers many of the newer developments and provides an excellent guide to designing and building your own inexpensive solar cookers. Another durable classic, Ken Butti and John Perlin’s A Golden Thread, covers the early history of solar cooking and has a good illustration of Mouchot’s solar cooker.

63 comments:

Rashakor said...

ok, let me first dispell a misconception about what is greenhouse effect.
The term has been highjacked by climatologist about 30 years ago to describe erroneously the energetic behaviour of earth atmosphere.
The real greenhouse effect, the one that actualy requires a greenhouse, cold frame or other similar horticultural device does not work because the cladding or glazing prevent infrared radiation from escaping. As a matter of fact, glass or clear polyethylene are not anywhere near infrared opaque.
The "skin" of a greenhouse prevents convection exchanges, by slowing down the exchange rate of the air inside the building. The greenhouse air absorbs the solar radiation and gets trapped inside.

Druid, the assumption you did about the trapping of infrared radiation is actually the atmospheric "greenhouse" effect where there is no physical barrier to convection. The albedo losses (energy radiated back to space) is only trapped by radiation.

Robin Datta said...

“Brother, Can You Spare A Dime?”

At that time a dime was made of silver. The dollar was backed by gold. The bulk of today's dollars are backed by magnetized rust particles on hard drives in the servers of the financial system from the Treasury Department on down. So the appropriate question would be "Brother, could you spare a Trillion Dollar bill?"

Cherokee Organics said...

Hi JMG,

Great topic. I concur with Chuck Burr's assessment of renewable energy. As someone who lives day to day on off grid solar power I understand it's limitations.

The limitation is really simple and almost unthinkable for those of us in the industrial world. You have to simply reduce your energy consumption when the conditions are not favourable. Shock, horror! I also have an energy budget of 3kW/h a day which I stick within.

For anyone interested in a comparison, have a look at your own electricity bill as it should show how many kW/h a day you use on average. It is also worth mentioning that heating and hot water here is supplied by solar hydronic, wood and a small amount of LPG (for convenience only as the LPG is used only when I'm feeling lazy).

The average household consumes 6x to 7x (probably more now) this amount of energy per day here. There is no feasible way you could keep up this supply with solar electricity. It's uneconomic as no one would want to pay for it.

Interestingly enough, I read in the letters to the editor page of a widely circulated newspaper here recently, a letter from an energy industry group putting the idea "out there" that the best way to lower electricity prices for householders was through a reduction in the expenditure on the maintenance of capital infrastructure. This is short term, profit motivated thinking at best, and at worst the beginning of the long descent.

I've also noticed that electricity supply outages (which is not a problem for me) have been affecting my neighbours more frequently in recent years. It's almost funny because, they'll get a cheque for $100AU from the supply company because power was not supplied on 25 separate occasions, but forget that on one occasion with the power out for 14 hours, everything in their refrigerator went off. I can see why gambling works with some people as they're focused on the wins and they quickly forget the losses... Oh well.

Anyway the above is not really that important, because I also read the other day that 70% of households in the state in which I live have air-conditioning units. I see these units for sale at hardware stores for around $799AU and they are rated to consume 6kW/h. The most concerning thing that I read into this is that the housing stock is so poorly suited to the environment that these units are seen as a necessity. This is a real vulnerability as in a low energy future, will these houses be habitable in the manner to which they are now? I think not. Secondly, it is simply not feasible with current renewable energy technology to supply electrical energy to these houses.

There are grants around for renewable energy systems (which for various reasons I did not apply for), but installing a 1kW/h solar grid connected system on your rooftop will do nothing other than ease your conscience. At best (down my way) these systems only generate about 6kW/h and at worst under 1kW/h. They also don't store energy for later use and if the grid goes down, then so does your supply which is automatically cut off to protect lines men.

Apologies to all as I'm banging on... There are just no easy answers that people find to be palatable.

Go the solar cooker!

Good luck!

Kevin said...

The anticipated prevalence of tarpaper shacks seems to conflict with another presumption which we have hitherto taken as more or less axiomatic: that widespread devastating poverty will shortly put an end to significant building activity. Yet here we're anticipating a building boom - in tarpaper shacks!

Even now, isn't it the case that while many thousands go homeless, there are even more thousands of empty housing and office units that could easily accommodate those who desperately need them? Only our callous and lunatic economic ideology dictates that people must die of exposure while the shelter that could save their lives goes empty. If this ideological mandate were to give way to sanity, a proliferation of shantytowns might prove needless. Since this is technically feasible, why shouldn't it be made socially feasible as well? Surely there's little benefit to landlords in possessing empty properties that steadily decay with every passing year.

By the laws of the same propertarian illogic: who will permit us to build tarpaper shacks on their land? A quick Google search informs me that during the great Depression of the 1930s the many Hoovervilles, mostly built on vacant public land, were for the most part barely tolerated when they weren't burned outright. Moreover, many places just don't have room for them. In the densely populated conurbation in which I dwell, there are no Potter's Fields waiting to be occupied by squatter communities housed in jerry-rigged dwellings. Here you must either live in the existing housing, or on the street, or under a freeway overpasse. It's hard to see any way the region could absorb a hundred thousand or more suddenly homeless people, and I'll bet this is true of a good many other areas as well.

This tragic situation holds great irony. I vividly remember that forty-five years ago much of history's most privileged generation actually *wanted* to drop out of conventional housing and live in improvised lean-tos or mushroom houses or various other assorted hippie shacks in the woods. They passionately dreamed of opting out of the existing infrastructure. But they weren't allowed to. The dominant order rigidly imposes upon everyone what Dmitry Orlov aptly calls "the iron triangle" - house, car, job - without which few can live. Now it seems that as this model falls apart, many will be forced out the comfy middle class dwellings to which no alternative is permitted except exposure, want, and premature death. What a generation once embraced with joy as an adventure in free living will now be a ticket to misery and despair.

Kevin said...

I'm *very* interested in making solar cookers. The more I reflect upon it, the more I realize that my long experience with artistic perspective - which is all about calculating the trajectories of rays of light - and with strange geometry like geodesics well suits me to design and make them. Moreover the power inherent in the principle of concentrating rays of light from a wide area into a narrow focus exerts great fascination upon me. Thanks to Mr. Google I've learned that with the right materials and design, the sun can generate enough heat to melt steel. Not that this will be needed for boiling eggs! I love the fact that for the latter purpose, cardboard and aluminum foil are perfectly adequate. It seems to me that the key factor is design, which I love.

(But secretly, deep down, I yearn to build a true solar furnace.)

To work with such intensity of light, I'm going to need to acquire safety goggles. That's what stopped me from getting started on the same project last Summer. Adequate ones cost a good chunk of money, which I must acquire fairly soon. I also mean to acquire a good supply of aluminum foil, since I'd hate to run out just as market delivery infrastructures fall apart.

It seems to me there's a connection between this technology and that of the "fireless cookers" (an amusing name, reminiscent of the antiquated phrase "horseless carriage" to describe automobiles). Though I didn't post about them last week, I mean to get busy on this technology as well. These and one or two other craft areas are now my principle focii of concentration. (Oh yeah - and growing food.) Clearly I'll need to acquire some of the sewing and metalworking skills mentioned in connection with the "umbrella" cooker.

Incidentally, there are two pieces of information I'd like to find and I'd greatly appreciate it if anyone can steer me to them. First, where can I acquire some of the cheap metallized fabric mentioned in this post? Second, can anyone point me to a good *graphical* method for locating the focus of a parabola? All the material I can find is based on algebra, which I loathe. I vastly prefer something derived from or compatible with the projective geometry used by engineering draftsmen.

22 Youth said...

Here here! Solar cookers are totally legit, and I say that from healthy experience. Dried beans cooked to soft in just one hour on a 4 degree C midwinter day in Dunedin, NZ. Even here with just 1600 annual sunshine hours we could replace 1/3 all cooking. The collapsable Square Foot Solar Cooker design is easily cobbled from scrap and collapses for travel, both suiting industrial collapse nomads well. Box versions possibly better for sessile tarpaper shackers. The SFSC can certainly distill alcohol too, thinking medical purposes. Will post image on GW forum.

Don Plummer said...

Regarding your first paragraph, John, NPR reported yesterday morning that the International Energy Agency is urging oil producers to ramp up production, lest increased demand for petroleum cause the price to rise to the point that the economy go back into a tailspin. The report went on to say that OPEC has indicated that they currently have no intention of increasing production.

The possibility that OPEC might be unable to increase production was not considered. But it's the closest admission to peak oil that I've heard from a major news media outlet, and it's the first time I've heard a major media outlet report that high fuel prices lead to economic slowdowns.

Fleecenik Farm said...

Oohh..I have a teenage son who is taking welding courses right now. Think I will show him the site and get him to work for me.:)

Glenn said...

Anyone consider using one of the larger 1980's vintage sattelite dishes as a frame for a solar collector? Seems to me the parabola is built in. Add mylar,or sheet metal leaves and you could have quite a powerful unit.

LOL on no one size fits all. In the current economy we cook with propane in the summer, and wood in the winter when we need the heat to warm our cabin. We're only slightly beyond tarpaper. We have insulation and outer walls. And with no mortgage, we get to keep it when the economy goes away.

Glenn

dltrammel said...

Here's a few links I came across:

"Capturing Heat - Five Earth-Friendly Cooking Technologies and How to Build" by WebLife.org (pdf). They have some well drawn out plans, though not very fancy.

Plans for a Collapsible Cooker that doesn't require complex drawing skill (with fun eagle head too).

The base model of the Eagle cooker is the CooKit here:
Solar Cooking Wikia
This entry has some useful hints too.

And the big page of links at BuildItSolar.
Cooking with solar

Which included this link for figuring out parabola designs for Kevin
AMSI Simple Tool for Parabolas

Cathy McGuire said...

Thanks for explaining the solar cooker! It tells me why my last one failed – I got the reflective, but with no glass, I didn’t have the retentive. I melted a bit of cheese, but that was all… now I have more to work with… though in the PNW, I’ll have to wait ‘til late Spring at least. But as one of my resolutions I’m gonna have that and the haybox working this year.

Was it just me, or were last Friday’s New Year celebrations a bit short on enthusiasm?
On this side of the country, I wasn’t wakened by gunshots or noise of any kind – I’m guessing they had nothing to celebrate, or they were afraid the new year would shoot back!

the New Year’s Eve blog post from Chuck Burr at Southern Oregon Permaculture was timely.
Yes, I read that, and though I don’t understand the details, it was clear what he was saying – that our lifestyle is unsustainable under any circumstances, and that more than half of our “adjustment” will be to use only a fraction of the power we now enjoy.

You know that point has arrived when a society begins neglecting its infrastructure, slashing basic services…
Yeah – that’s what’s finally getting my friends and family to “wake up”, but unfortunately not far enough to decide to adjust… they’re still in the “bargaining” phase of grief. I suppose Burr is right in that having some alternatives for a while will give more people a chance to work through the grief process and be willing to adapt. No help coming from the rich, that’s for sure!

I’m afraid I don’t see how people will adjust downwards to tarpaper shacks from McMansions (or MiniMc’s)… I suppose they will try to close off a portion of the vast, totally open spaces that are popular in these models. Or a quick shift, once the house goes into foreclosure… but since our US zoning laws are so much stricter since the last Depression, it will be much harder to even create something ad hoc.

One point that popped up in my mind as I was reading several new years posts, is that population growth is often driven by the need of a couple to have many kids to help them – first, around the house and on a farm or in a shop and then second in their old age, when there is no “social security” or equivalent – the kids are “it”! We’ve forgotten why people had big families (it wasn’t just because they were “fun to make”). Now that many industrialized nations are both threatening social programs for the elderly and saying we want less population… sounds like a real gnarly social problem. Wondering if you’ve thought or read about this, and what thoughts come up… I wonder how rural China deals with this? Or has population gotten so large that no one has more than a 2-person farm?

Thanks again for the great post!

GHung said...

The concept that certain appropriate technologies are not appropriate all of the time is, well, appropriate, though it's a concept that is tough to impart to the uninitiated. My home was built incorporating these ideas.

"How do you heat your home?"

Passive solar, mostly.

"What if the sun isn't shining?"

We fire up the woodstove.

"How do you power your home?"

Solar electric mostly.

"And if the sun doesn't shine?"

We turn things off.

... and so on. Folks have a hard time with intermittancy, though this has been the norm for most of our history. I welcome it now.

Kevin asked about how to calculate the focus of a parabola, above. While others can answer his question better than I, I tend to look for off-the-shelf solutions. My suggestion is to find an old satellite dish with the feed horn intact. I've been using these for years and folks usually give them to me if I'm willing to drag them out of the brambles. The dish is already focused on the feed horn. I plan to use one to make a solar concentrator. The hard part is keeping them aimed, which can be done fairly inexpensively with available electronics. The other option is to manually aim them, tedious but doable. The old 3-4 meter dishes also make great roofs for a shed, hen house or your tarpaper shack ;-) Smaller dishes work well for covering a food cache or root cellar.

Even tarpaper shacks can be passive solar; one or more scrounged windows, a packed earth floor and stone pavers. A trombe wall or a pile of rocks will absorb alot of heat during sunny times. Barrels of water work nicely as well, doubling as H2O storage.

As a scrounger I look for things that may be useful in the future. I have several boxes of mirror tiles in storage and a few sheets of foil backed poly-iso insulation, either usable for building a fine solar oven. Under most circumstances this stuff is junk; unlikely to be stolen (though it may have trade value at some point). Things like this can be shoved under a bed if storage is a problem. Even if I lose my home at some point I have trained my eyes to look for discarded items that may be of some use.

Cherokee Organic's post is important in that the time to learn to function on less is now. While I've been walking this walk for years, I admit that there is a learning curve as well as the risk of backsliding into complacency. The temptation to adopt many energy and resource intensive stategies is strong and offered up daily. Learning to do more with less (or less with less) involves developing a new comfort zone, one that most folks will never achieve. How long will it take one to become comfortable with constructing and using a solar cooker when one has never heard of one? That is why I share this and other similar sites whenever possible.

risa said...

Illustrations of prior collapses often show shacks peppering the sites of great cities and buildings, with those buildings undergoing dismantling. We don't move into the empty structures because they can't be maintained well. So we take them apart and re-scale them. Tar-paper shacks are an apt symbol of what in fact happens. The current tent cities are the precursor.

At our place we've re-purposed old building materials from elsewhere for decades. Ours is now the shoddiest-looking place in the neighborhood, but it is also owned free and clear, and we are sometimes below 3K in power consumption.

In winter, our cooking can be done entirely on wood (and it's cold, cloudy and windy the whole time). Dehydrating season is very short (Western Oregon). But our home-made (from scrap) dehydrators run a bit too hot, and that has encouraged us to think about at least trying a cooker. We might yet.

Dustin said...

Have you seen what kind of things the Open Source Ecology folks are working on?
It sounds like that have a very valuable and well-thought out solution, with a group of tools that will enable people to create their own self-replicating renewable economy in a box. It's not for everyone, but it makes sense to me. I think they are on the right track.
Take a look:

http://openfarmtech.org/wiki/

Lance Michael Foster said...

re: dimes. I bought five battered silver dimes yesterday at $2 apiece (silver content) from a coin shop. They were too worn for collectors and that's not I wanted them for anyways. Every time I get a couple extra bucks, I plan on buying a dime or two.

re: solar energy. The most efficient use of solar energy is not panels and generating electricity. Solar energy is great for growing plants (gardening) and passive solar heating for housing (the old, south-facing big windows with dark-painted floors and dark-painted metal drums used for holding water, which can also be used to heat baths). And for cooking too, and disinfecting. And healing (sunbaths for certain physical and mental/emotional ailments).

re: tarpaper shacks. My grandpa lived in them and I have known many who did. They work best if you combine them with a dugout (earthshelter, with tarpaper/frame roof) and careful drainage planning. They don't last forever, but long enough to build something more substantial, if you can. Speaking of dugouts, don't neglect sodhouses, earthlodges, earthships, and all the other varieties of human-caves :-)

One thing I read today was just a reflection of how much cognitive dissonance we are facing (I expect more and more people to face mental problems as this continues). An article on Yahoo talked about all the things babies born in 2011 will never know, like paper maps and watches. After all, you don't need a watch if you have your trusty smartphone, and you don't need a paper map if you have a GPS in your Escalade!

So we have a chunk of the population who are adamant about a Jetsons-Google future and the rest of us preparing for the Great Depression leading to a medieval future. Talk about cognitive dissonance! We have a real schizo immediate future laid out for us.

Lynford1933 said...

At the present time compared to our long desent future there is an abundance of excellent materials to construct solar cookers. One such is #8 stainless steel sometimes called 'mirror' stainless. It has an exceptional long life, moderately priced now, in thin gages easily formed, but be careful. A carelessly placed parabolic can set your tar shack on fire. Three or four small solar cookers can cook a multicourse meal and heat your tea afterwards. Even the commercial "Sun Oven" at about $250 USD complete with cooking pans, bread pans and cookey sheets is available, durable and quite usable. Buy three 12" square mirrors used for home decoration and mount them like a the corner of a box, point to the sun can heat water to boiling in a few minutes. These are all simple.

Watch this for a group cookout.

http://www.bbc.co.uk/news/science-environment-11385534

BTW: RASHAKOR is correct in his discription of solar greenhouses.

If you want a greenhouse, think hoop house and enjoy fresh salads in december. Be sure to include a Trumbe Wall for night heating.

All up for now enjoy these Green Wizard things now. They are fun and interesting. They will be required knowledge for my grandsons after they give up 'texting'.

Lamb said...

To Kevin....if you are looking for inexpensive fabric to make an umbroiler cooker, hie thee to any sporting goods store, Army/Navy surplus store or, heck, most of your *big box* stores carry them, as well as discount dollar type stores...a "Space Blanket"! It is not fabric, but Mylar, but could be glued or CAREFULLY sewn into myriad shapes and configurations! EXCELLENT at reflecting heat!
As for building a box cooker, I suggest the small investment into some "flashing" from your local home improvement or hardware store. Just as reflective as aluminum foil and much sturdier! A pair of tin snips and a pair of pliers to make cuts and bends and you will be able to make a sturdy, long lasting cooker. You can polish aluminum or steel flashing to a mirror like finish to enhance the performance of your cooker. Insulation for your box cooker can be easily obtained at any building construction site....just ask for insulation scraps!
One expense you might consider is purchasing a black soapstone or black granite or marble even for the bottom of your cooker box to *store* heat. A small stone, cut to the measurements of the bottom of your box can lengthen your cooking time past sunset or increase the amount of heat produced in the box for more *heat needy* recipes or on less than sparkling sunshiny days.
Hope that helps!

Ruben said...

@Kevin

I went looking for a method to use a framing square to draw a parabola, which I remembered from the Mother Earth News. Couldn't find it, but here is a free calculator you can print from.

Also an interesting comment in a longer thread about solar parabolas.

And a nice drawing from Fine Homebuilding using a compass and a ruler.

As far as fabric, I would try space blankets, maybe backed with another material. Sew it all up, though you may need to use tissue paper during sewing to prevent creep in the seam. But check out this fabric and especially this fabric on eBay.

Richard Larson said...

Yeah but, one doesn't need an expensive PV system on a tar paper shack!

I have experience, not with a tar paper shack, mind you, but with a 60 watt panel, 4 used marine type batteries, 4 sevenish watt LED light bulbs (40 to 60 watt equivalent each) (with self-contain PV lanterns for back up/assist). Along with the lights; a 10 inch DC COLOR TV with DVD function, and a integrated DC VHS player, with enough "How To" tapes and DVDs to keep me in things to do for the rest of my life. The batteries store way more than enough to light my enormous 20'x24' cedar log camp - even through cloudy conditions. However, something new is a yet to be installed is another 630 watts of power with matching controller. Boy, will I be in power glory then!

Hey, since I am smart enough to plan ahead, I deserve to have an upscaled shack to live in..

Back at the house is another matter, I have been taking steps to lower my energy consumption, including already having a solar water heater and a solar air heater installed. But cooking is something apart from heating and we use an electric stove. This is one appliance - I was surprised to learn - in the house that uses a lot of electricity. Just never thought much about it.

Back at the camp, we have a woodburner for heat, and it is practical, during fall spring and winter, to use it for cooking. I use a small metal barrel, with grate welded in, a cover, and a hole to fit a thermometer through. When placed on the woodburner, it is all one needs for baking, a pan right on the burner for frying. But in the summer, when one doesn't need to heat the camp, or on otherwise warm sunny day, a solar oven would be just the ticket. I am going to be Green Wizard when I'm at camp!

Back at the house, where we spend 90% of our time, and use nearly 100% of our energy inputs, is what I am working on now. Now today the solar oven will become a part of the routine. Someday soon I may just turn my home into camp too.

Thanks a lot!

Bilbo said...

For anyone who wants to experiment cooking outside on a cloudy day, small rocket stoves can purchased from stovetec. I have one it works well using the tree limbs that fall off occasionally from my trees.

Copy and paste the line below into your web browser to see.

http://www.stovetec.net/us/stove-products/1-rocket-stoves/17-stovetec-stoves

Jon said...

One "high tech" improvement on Tar Paper that I look forward to using in my Hooverville, is EPS foam sheething. 4x8 feet in size. Workable with a pocket knife. Water resistant. Wind proof. Great insulation (especially important for putting under the bed roll to stay warm.) Combine with a spray can of "Great Stuff" and you have an instant house building kit. Easily painted. Similarly with bubble wrap windows. Far better than old onion paper windows.

John Michael Greer said...

Rashakor, okay, I stand corrected. (The explanation I used is given in several of the solar greenhouse books I've got.)

Robin, a dime in 1930 was about equivalent in purchasing power to a $10 nowadays -- you could get a loaf of bread for a nickel back then. Mind you, if we go hyperinflationary, and of course we very well might, "Brother, can you spare a trillion?" might make a good line for a song.

Cherokee, exactly. The only way to live on renewables is to use much less energy. That's the completely unpalatable reality that most people are trying to avoid.

Kevin, you make tarpaper shacks out of scrap from houses and other buildings that have been abandoned and are falling down. (Tarpaper was used in 1920s home architecture for the same things that Tyvek wraps are now.) Since a very large fraction of the homes thrown up (in any sense of that phrase you care to use) in the recent housing boom were very cheaply made, and will be tumbledown wrecks in the not too distant future, I'd expect to see them being scavenged for raw materials soon enough.

Training in perspective ought to do you very well as a foundation for building solar cookers. If you're minded, keep the Green Wizards forum posted on how it goes; others don't have that background and could benefit from your knowledge. That might also be a good place to get info on mylar fabric and parabola construction.

22, dried beans cooked in an hour? Good heavens; your solar cooker is more efficient than the ones I've used.

Don, when it actually sinks in that OPEC can't increase petroleum production, and neither can anybody else, the shockwaves are going to be worth watching. I give it another five years.

Fleecenik, hand him some books on solar cookers and see what he can come up with!

Glenn, the one problem with parabolic mirrors of any size, and also of fresnel lenses, is that you get extremely high heat at the center -- too hot to cook with, hot enough to instantly incinerate organic materials and heat metal to the melting point. A solar furnace for craft use is a good plan, for cooking, you want a cylindrical or flat mirror, so you get diffuse heat rather than a single point of incandescence.

sgage said...

@Glenn,

With the rig you are proposing, you stand a very real possibility of vaporizing your cooking vessel along with its delicious contents! I have seen some mind-boggling demos with my own eyes.

Now, if smelting metal is your game, you are on the right track. But for cooking...

John Michael Greer said...

Dltrammel, thanks for the links! These are great.

Cathy, yes, you need the glazing to keep the heat in. Thermal mass is also useful for that -- a lot of box cookers put a metal tray painted flat black in the bottom, to soak up as much heat as possible. As for people dealing with the transition from McMansions to tarpaper shacks, that's going to be an explosive social issue in the very near future.

Ghung, the easy way to orient a parabola to the sun is to use an equatorial mount, the kind that amateur astronomers use for their telescopes -- you can find detailed plans in old books on building your own reflector telescope. Because they're oriented to track the sun (or anything else in the heavens) across the sky, you don't have to fiddle repeatedly with aiming; once you've got the dish pointed in the right direction, you simply give it a nudge or turn a crank at intervals, or have a motor and some gears to do it for you.

Risa, back in the 70s there was a lot of work done on solar cookers in Seattle, which has more or less the same climate you've got in western Oregon. I'd give it a try!

Dustin, no, hadn't heard of them before. Thanks for the tip!

Lance, that cognitive dissonance is, I think, going to become one of the most explosive social forces of our time. Those who bail out of the Jetsons future and get to work on something more realistic will be much better prepared to deal with the world that's left when the Jetsons fantasy crashes and burns.

Lynford, thanks for the links and info! As for greenhouses, I'm partial to something a bit more substantial than hoop houses, but to each his own.

Lamb, those are excellent points. I've seen fabric with mylar glued onto it for sale at ordinary fabric stores, too.

Ruben, thanks for the links!

Richard, as long as you can get the parts, a salvaged PV system is fine. It's just not going to be viable once the factories that make the parts go away.

Bilbo, thanks for the link.

John Michael Greer said...

Jon, my guess is that sheets of Tyvek stripped from defunct subdivisions will also be in high demand. Me, I prefer natural materials, but when you're close to the edge you use what you can get.

Sgage, bingo. A solar-powered smithy, with a parabolic mirror used to heat steel to forging temperatures, would quite possibly be an option.

sgage said...

"A solar-powered smithy, with a parabolic mirror used to heat steel to forging temperatures, would quite possibly be an option."

I really have seen some rather astonishing heat levels achieved with a re-purposed old-school parabolic thing.

My neighbor is something of a smith (along with competence in many other ways of metal working - this guy is going to busy no matter what). I have been trying to get him to experiment with solar, but he's hard to convince. I need to drag him up to DAcres here in NH, where they rigged up something like Glenn suggested.

People who think solar is some sort of wimpy game need to see a big rig in action - they will quickly change their tune! Think "Archimedes setting the invading fleets on fire with his mirror" :-)

dr-beowulf said...

Seems like you could make an insulated box do double duty as a fireless cooker and a solar cooker. You'd just need two interchangeable lids -- a thickly insulated lid for when you're using it as a fireless cooker, and a glass lid plus a reflector for use as a solar cooker. Has anyone tried that?

dltrammel said...

I have seen here in the Midwest of America, that the Middle Class has started to wake up to the disconnect. Property taxes are a real eye opener. Local governments are having to raise them since sales tax revenues are down. People are saying, "Why are my taxes going up when my property is worth less."

Our city put a bond issue to pay for street repair and such, on a recent election ballot. People were all saying "Why are we borrowing money we don't have?" They are waking up to the fact that money isn't there anymore and the tightening of the budget is going to get bad.

Kathy McGuire said: "Now that many industrialized nations are both threatening social programs for the elderly and saying we want less population… sounds like a real gnarly social problem. Wondering if you’ve thought or read about this, and what thoughts come up… I wonder how rural China deals with this?"

Saw this article on the BBC where China is considering making it a law to visit your parents. Nearly an eight of their population is over 60 and with the 1 child policy there are fewer and fewer young people.

The comments are very interesting to read too.

And: "I’m afraid I don’t see how people will adjust downwards to tarpaper shacks from McMansions (or MiniMc’s)… I suppose they will try to close off a portion of the vast, totally open spaces that are popular in these models."

I suspect that people will move back in with relatives at the start. Remodeling basements and other such things. Maybe even a Tiny House kind of deal. Build a small dwelling on a relatives' property.

Or friends will group home, sharing space and expenses. Might not be a bad thing to get the re-start of extended families going.

Watch local governments trying to restrict occupancy numbers soon when the Haves start complaining about the HaveNots. Just won't do to have all those people living in one home, never mind all the ones with For Sale signs on them from foreclosures.

Roy said...

Very good as usual, but as I read this one idea kept popping into my mind. If the world is inevitably going to lose our industrial status, why not just document that and some techniques historically proven to be effective for survival and sufficiency thereafter? It would seem more reasonable at this point to partake in ecclesiastical politics and perhaps attempt to influence legislature. And if you bring enough peers to your city council, you can pass laws.

Evan said...

I wonder if flat white paint might do a better job at reflection than aluminum foil which, though it looks shiny, actually diffuses light as opposed to a flat white surface which reflects it.

Either way, as others have mentioned mylar is a good option, and yes, you can get it for free. I pick up the remains of those shiny balloons with "Happy Birthday!" messages on them because they are made of mylar and with a pocket knife you can slit that thing open and use it as a reflector.

Cheers,
Evan

Glenn said...

Sgage, JMG,

I just thought it might produce more heat than a box with a couple of reflectors. I had no idea it might be as powerful as you both suggest. The potential uses are interesting. It might be nice to be able to forge without coke or charcoal.

I'm not a smith, but I was an apprentice once, and one of our neighbors is apprenticed to one now.

John Michael Greer said...

Sgage, I've occasionally considered a new career as an environmental mad scientist. A solar-powered death ray, using Archimedes' techniques as inspiration, would certainly be a good starting point!

Dr. B., you'd also want to have additional insulation to pack into the oven box to fill up the space between the walls of the box and the walls of the pot when using it as a fireless cooker -- the closer the insulation is, the better a fireless cooker works. Still, it's certainly a possibility.

Dltrammel, harsh though it's going to be for people to do without the amenities those bond issues can buy, that's the necessary wave of the future. We simply can't afford to live the way we've been living for much longer, and the sooner we start downshifting, the better.

Roy, if that's the work that calls to you, get out there and do it. Politics isn't something I'm good at, so I'm doing something a little different.

Evan, an interesting question. Why not build two cardboard box cookers, one with foil and the other with opaque white reflectors, and see which one works better?

Glenn, a lot of people miss that! People who build solar furnaces are constantly having to keep people from sticking their hands into the focus point. Folks don't realize that their hand could quite literally be burnt to a crisp in the time it took them to feel the pain and yank it back out.

Kevin said...

Many thanks people for the excellent information on parabolas and solarian cuisine. What with the links I have some pretty substantial follow-up homework in front of me. I'm looking forward to it.

Lance Michael Foster wrote:

An article on Yahoo talked about all the things babies born in 2011 will never know, like paper maps and watches.

That's most likely because no one in the States will remember how to make either of those items - especially the watches - nor be able to afford any of the Swiss models.

Yahoo is one of the biggest propagators of bull around. Just a day or two ago one of their headlines declared that this Christmas was the best for retailers since 2007 (big whoopee), and maybe even the best ever. Last year they described the then latest oil find as "The Oil Well That Changed the World Forever." I don't know if they're actually that stupid or are just assuming their audience is. I suspect more of the latter.

It'll be interesting to watch the Jetsons maintain their iPod-driven lifestyles while occupying brand new scavenge-built yurts and teepees.

Speaking of which, I'd far rather live in a well-made yurt than a wretched shed cobbled together from toxic tarpaper. The yurt is well proven as suitable for human habitation, and in some pretty tough climates too. I believe Teepees also have a relatively decent track record.

JMG, you're dead right about the recent New Year's, er, celebration. It was nothing if not spiritless. I found it quite restful.

Kevin said...

The idea of a solar smithy or foundry is definitely of interest to me. The ability to manufacture custom-designed pieces in cast metal will surely be valuable. It ought to work for glass too. Archimedes is where it's at!

wreckage said...

Have you read any of Ron Edwards "bushcraft" books? It is a series of depression-era and frontier-era techniques, skills, remedies, and make-do technologies from Australia, where the Depression and Frontier eras partly overlapped.

I can't think of much that would better fit the tarpaper shack principle! They're also great for historical, folk history and oral history purposes. Published by Ram's Skull Press.

Bill Pulliam said...

Many people already are living in tarpaper shacks whether they realize it or not, given construction standards on many houses built in recent decades! Of course they may have paid several hundred thousand dollars for their shack...

Evan -- you have your reflectance properties reversed. Flat white surfaces reflect light diffusely in all directions; this is why when placed in the sun they look white from any viewing angle. Aluminum foil (smoothed out) reflects light highly directionally. This is why foil in the sun looks extremely bright from a narrow angle, and dull gray (from reflecting incoming light from other diffuse sources, like the sky, the surroundings, etc.) from other viewing angles. Go ahead and try it; but I expect you will find that your white cooker does not heat up any more than it would if it had no reflecting panels at all.

The "flower" design versus the parabola -- the "flower" is more forgiving of wrinkly foil, as the light will get funneled down into the box even if the reflective angles are a bit off. A parabola needs a very smooth surface to work best. On the other hand, the parabola only reflects the light once whereas the "flowers" reflect it a couple of times, so there is better efficiency there for the parabola. Experiment!

Re: solar greenhouses. Simple greenhouse designs even with thermal mass are impossible to keep above freezing in winter without supplemental heat throughout most of North America except for the west coast, the low deserts, the gulf coast, and the very far southern east coast. Even with large thermal masses they tend to freeze in the cold cloudy spells in other areas. So for most US residents you will only enjoy salad greens all winter from your solar greenhouse if it also has a heater in it. But that's another topic...

Wolfgang Brinck said...

How to cook food without a ready supply of electricity or gas is surely a problem. And I am not sure how good a solution a solar oven is. I suspect it may be an interim solution to the energy problem. What struck me when I looked at the page with all the solar cooker designs was that every one of them used aluminum. Aluminum is plentiful for now, but requires a good deal of electricity to produce. It wasn't even produced in commercial quantities until sometime in the 20th century. The question is, in a world where petroleum production has collapsed will we still be allocating electricity to aluminum production? Perhaps, and in the meantime we can scavenge. Perhaps we can make solar ovens without aluminum. Zinc coated steel sheeting would work. Conventional mirrors would work, though the glass would be heavy and would require a complicated framework.
The other problem with solar ovens is that they do not supply on-demand heat. One has to schedule one's cooking for when the sun is available. I doubt that they would be popular this time of year in Alaska. And unless you have a house that is designed to let in a lot of sun, you would probably have to use your solar oven outside. If you add up all the disadvantages of solar cooking, you might easily be persuaded that a quick fire of small sticks might be a better solution to make your tea at five in the morning.

Nicholas said...

Mr. Greer,
I teach honors English at a Montessori High School, and would like your permission to print copies of your articles on cultural narratives from this website, and to make scans of the relevant selections from your books The Long Descent and Ecotechnic Future.
Thank You

provo said...

Regarding hands in the focus -- my largest dish is 6 feet in diameter, covered with 3" square mirrors. The focus is about 6" wide. When I show it to someone for the first time, I hold a 2x4 at the focus, and it bursts into flame in a couple seconds -- no more worries about THAT person's hands :-)

Incidentally, that dish can just melt silver solder -- even melting aluminum would take 8-10 foot dia., I believe. Forging iron and steel would take a VERY large concentrator.

Kevin said...

Provo, what about the goggles / eye protection issue? What's your safety practice when working with a reflector as powerful as that?

It seems to me that even with a dish of that size (six feet diameter), if the facets were 1 inch across instead of 3 and the focus two inches across instead of six, in return for accepting a smaller focus you would get nine times the concentration of solar energy in that spot - assuming that the inverse square law applies for heat (which I'm not sure of) as well as for light (which I'm pretty sure it does).

That size focus is hardly big enough for a crucible (except perhaps for jewelry production), but I would think the principle that determines what temperature you can reach is not the absolute size of the reflector, but rather the size of the focus relative to the reflector's gathering capacity.

If that principle holds, then even if you scaled down to a fraction of those dimensions, with a dish only a couple of feet across, in theory you should still be able to produce a very tiny focus of very intense heat. Not very useful perhaps, except maybe for cutting small pieces of thin sheet metal. A solar sheet metal jigsaw is what you'd have there.

All of this presupposes that the reflector is built to the highest accuracy, with each facet or segment of reflector directed with extreme precision upon a common focus: a task which might prove beyond the technical capabilities of shack-dwelling technicians. Still, one can dream.

John Michael Greer said...

Kevin, I have a great deal of respect for yurts, tipis, and most other traditional indigenous housing styles; given the choice between a yurt and a tarpaper shack, you'd find me in the yurt right away. Still, you must admit that referring to tarpaper shacks gets the point across better.

Wreckage, I haven't! One of the downsides of living on the other side of the planet, I suppose. ;-)

Bill, the detailed tests in The Solar Greenhouse Book appear to contradict what you're saying -- the folks at Rodale, for example, kept an unheated solar greenhouse going through a Pennsylvania winter. Admittedly they used a lot of insulation and thermal mass!

Wolfgang, alchemists were using solar ovens in the fifteenth century, so clearly there are alternatives to aluminum. As for the fact that solar energy isn't there instantly whenever you want it, er, did you read the bit in my post where I addressed that? Of course you don't use your solar oven at 5 am; you use it to cook dinner, so you can afford the fuel to cook breakfast!

Nicholas, you can certainly copy posts from my blog. If you want to copy sections from my books, though, you'll have to contact the publisher, New Society Publications; they hold the reprint rights.

Provo, the square mirrors are the limiting factor; that's why the hot spot is 6" wide. If you mirrorized the surface of the dish directly, you'd have a much smaller and hotter focus.

Kevin, indeed one can dream. And experiment, of course.

DIYer said...

It might be worth noting that aluminum, and other shiny things, will probably become more dear as we descend the energy decline. Much like silicon, it takes a huge amount of electricity to win aluminum from its ore.

So again, we are perhaps talking about a way station more than a long-term sustainable solution.

Bill Pulliam said...

The Solar Greenhouse Book (I have a copy also) was also promoting a product of sorts, which tends to make peoplr present the most favorable data. Actual experience with greenhouses that are not massively engineered is that they require supplemental heat. I think most naked hippie types have found a wood stove is easier to engineer than the tons of concrete, double glazing, insulated subsoil foundations, etc. to make a winter-proof temperate greenhouse. Sometimes it's just not worth the effort, ya know?

I'm curious to make an open-bottomed model that floats on a pond (using the pond as winter heat source) and see what happens.. someday.

wreckage said...

For your readers, a link:

http://www.ramsskullpress.com/crafts.html

Source for practical guides to tinkering, survival, leatherwork, knotwork, and traditional Chinese mud building; how to shape timber for building using very very basic tools such as saw and adze; how to make a proper dirt floor; and so on.

Sorry to spruik, I was always fascinated by bushcraft as a kid and thought your readers might find these books both delightful and useful.

They are beautiful in their own right, lovingly illustrated by the author, and full of anecdotes and tales from and about the people from whom he collected this unique combination of practical skills and folklore.

provo said...

Kevin & John -- You raise a good point. Some tasks require high power at low temperature, like raising 3 gallons of well water to boiling in 20 minutes. Other tasks require high temperature at low power, like melting silver in a small crucible.

Tight focus is needed for the latter, but not the former. In practice, the small errors in the surface (fiberglass laid up on a homebuilt parabolic buck) set a limit to the possible concentration, which can't be helped by smaller facets. Maybe in the next version :-)

DIYer said...

JMG,
I have a quibble, well really, a correction to the correction posted above.

First, from Wikipedia:
The greenhouse effect was discovered by Joseph Fourier in 1824, first reliably experimented on by John Tyndall in 1858, and first reported quantitatively by Svante Arrhenius in 1896.
So it's been more like 185 years ago that the greenhouse effect was first contemplated. (to the extent you can trust Wikipedia)

Secondly, window glass and plastic are opaque to thermal infrared (~8..12&micron;) radiation. Thirty years before the controversial airport scanners, I had an opportunity to be in a facility that designed night vision equipment for the MIC.

These night vision gadgets, while they can see at night and through clothing, cannot see through the glass windows of the building they are in. In the imager, plain glass windows are as black and shiny as the imager's lenses are to the unaided eye.

But I will agree with Rashakor's point: if your greenhouse had ideally transparent diamond windows, it would still inhibit convection and would remain warmer on a cold night, or hotter on a sunlit day. The opacity of the glass merely adds a radiation barrier to the convection barrier.

TG said...

This might be a good time to mention that I successfully dried a small batch of raspberries in my Tulsi hybrid solar oven late last September, after the Archdruid inspired me to experiment. ;-)

I found the process time consuming, as the temperature had a tendency to creep up, even with the glass panel propped up an inch for venting. So I had to frequently reorient the oven at various oblique angles throughout the day. Another drawback is that only one rack at time fits in that style of oven. I used a cake cooling rack draped with cheesecloth, since I had already had those items handy.

But yes, that does work in a pinch. I added the dried raspberries to my cereal and ate them that way for the next few mornings. They were definitely edible, albeit a little crispier than ideal.

--Tracy Glomski

Eve said...

sorry if this is somehow a repeat, as I am responding before reading all the comments, but wanted to pass along this info about parabolas. Although I suppose this is still algebra, a parabola can be constructed by paper folding, and perhaps the poster who asked this question can adapt this to whatever it is he needs for his solar furnace. Draw a line and then a point somewhere above the line, sort of the middle. Repeatedly fold the paper so the point touches the line, all along the line, crease, and you will have a parabola.

Today I was making rice and took maybe 10 second to put some towels in a cardboard box awaiting recycling, put in the pot, and had a successful fireless cooker. Brown rice probably would take a little more planning, but this worked great for white rice.

Thardiust said...

Here's a pretty interesting article, with links to other articles, about Forest Gardening.

http://en.wikipedia.org/wiki/Forest_gardening

Slow Crash said...

JWG,
Great article. I sweet-talked my 11-year old daughter into building a solar oven for her science fair project. For a reflector, we simply used an auto windshield shade, the shiny insulated type that fan folds. It was not as efficient as most solar ovens, but it shows you can use most any shiny surface to build a solar reflector.

Also, year-round energy-free greenhouses have been built in cold weather climates. Mike Oehler has one in northern Idaho that he describes in his book, "The Earth-Sheltered Solar Greenhouse Book", available at his website. From what I have read in his book, I am confident it would work, and any handyman could build it. Not quite as simple as a solar over, but definitely one more tool for the Long Descent.

Glyn said...

I fancy having a go at a solar cooker and have made making one one of my new year's resolutions.

Regarding aluminium being temporary and expensive, what about the possibility of cutting open and using aluminium beverage cans? Could that possibly work as a cheap/free option?

LewisLucanBooks said...

Kind of off topic, but, perhaps a reminder as to why this stuff is important and urgent.

"The Nation" magazine is starting to post a series of videos called "Peak Oil and a Change of Climate." I think this is the first one. It's about 20 minutes long. Commentary by: Bill McKibben, Noam Chomsky, Richard Heinberg, Dimtry Orlov, James Kunstler, etc.

I posted it on our local newspapers on-line forum. I'm sure the comments will be "interesting."

http://www.thenation.com/video/157441/peak-oil-and-changing-climate

dZed said...

Sorry if this appears twice. It didn't seem to send the first time I tried it, so I came back later in the day and edited it and resubmitted.

You are correct, John, in saying that the true appropriate technology is, by definition, not going to work for everyone, everywhere -- its design is based on certain assumptions about location, use, environment, culture, etc. Taking that point, your discussion of solar cookers should, in my opinion, be amended to point out the differences between using what I might call "passive absorption" technologies vs. what I'll call "concentrating technologies" in the NE US, vs. the SW US. There is a reason the great solar concentrating 'power towers' are being proposed in Spain and the SW US -- it's very, very dry there. Any humidity in the air (and consequently suspended dust and dirt particles) reduces the amount of DIRECT sunlight significantly. Not that it can't still be sunny, but that sunlight is now DIFFUSED sunlight. Diffuse sunlight is impossible (or at least very difficult) to concentrate (This is also why "ducted" wind turbine designs that claim to gather or concentrate wind are uniformly bogus -- tracking the wind 100% of the time is fiendishly difficult. We're much luckier that we know where the sun is going to be!).

In other words, while concentrating type solar collectors can and do work in humid areas like the NE US, they will be significantly less effective than they would be in drier climates, and much more subject to the whims of clouds and the movement of the sun (a concentrating collector would have to be pointed directly at the sun, ideally anywhere, but even more so in a humid climate).

Combining the two technologies (as the fanned apparatus around the normal solar box cooker) would 'avoid' this problem by being passive as well as concentrating, but the other coned designs (anything where you're placing an object at a foci), the user will find much, much less effective in a humid climate.

I can certainly vouch for solar ovens, with and without reflectors. I've had many a pot of stew or baked sweet potatoes after a day outside. It is pretty disappointing to set one out with the hopes of warming something up and coming back at lunch time to find it hovering around 80 degrees instead of the hoped upon 280. That's when you eat cold stew! The best implementation I've seen was in an old Home Power magazine. A lady had basically installed a solar cooker on a south facing side of her house. She removed a window, installed a thinner version of a cooker into a shelf that extended outside the building, and reinstalled a smaller window above the cooker back wall. She then made an insulated door/plug that she pulled out. It seems it might be a long reach to get anything in and out of there, but it was certainly an elegant solution. I've seen the same idea with an unused door frame and a winter time fridge.


Thanks!

spottedwolf said...

John...
for those who may be interested...

Stocking Up.....Rodale Press 1977

ISBN 0-87857-167-1 hardcover
0-87857-221-X deluxe

By Carol Stoner (love the name)


also edited one called organic gardening and farming.

later bro........

Brad K. said...

Kevin,

"Only our callous and lunatic economic ideology dictates that people must die of exposure while the shelter that could save their lives goes empty."

Yes, it does seem sad. One question - at what point are you able and willing to abandon, as a community, the rule of law? You casually suggest that taking what someone owns because someone else could use it is the "right thing", so how do you propose to retain your shelter, your food, your clothing, your autonomy to decide what activities to pursue, to provide for your self, your future, and the welfare of those you care for?

What is good for the goose is good for the gander. I don't dispute that using abandoned structures as emergency shelter makes sense. But we still have communities enforcing zoning and code regulations, we still have lawyers and activists championing the rights of the homeless and poor. This makes voluntarily surrendering property for such a purpose as ad hoc housing a legal nightmare. Let it be officially acknowledged that squatters aren't being evicted - and the owner, aware of the situation or not - could become seriously victimized by "due process" - whether the 'owner' is the community or an individual. A corporation is responsible to owners for maintaining assets - including protecting property from competing claims, such as those of squatters.

You ask how to find the focus of a parabola. First, magic, or wizardry if you will, is the result of learning and work, not the result of a string of "this was fun!" activities. Algebra with geometry seem to fall into the category of un-fun things that open vistas, to those that master the skills. Even when the actual techniques are never, ever used after the initial study. So, I would break out the Algebra - and geometry - and become better acquainted with Mr. Mathematics.

Back to the parabola. I might take a three strings and tie one to each of three evenly placed spots on the edge of your parabola. Tie them together at a point where they are each the same length as the others. This gives the axis, approximately, through the center of the parabola. Now experiment - your focus should be somewhere on that axis. Use a stick to find the solar focus, not your hand!

One of JMG's earlier discussions centered on the amount of energy available. On your nicely polished, tightly focused two-foot reflector I would suspect your focus would be as hot as could be. On the three foot reflector, the amount of energy you can extract from your device will be considerably greater, even if the actual focal temperature were lower because the focus was more diffuse.

I use a plasma cutter, at times. The device is rated for the thickness of metal, and the inches per minute it cuts. The thicker the metal, the slower. And trust me, the temperature and amount of energy available from the plasma cutter is nearly constant, depending on wear of the contact and electrode.

I have to assume that your solar forge or solar cooker is going to experience a similar heat experience. That is, it isn't the temperature of the focus that heats the beans or metal, it is the amount of energy transferred. Drop the temp by half, and increase the amount of energy by 7/9, and by golly - the beans get hotter and cook quicker.

Heating a pinpoint area of aluminum or silver usually doesn't accomplish much. Usually the task is to heat, and melt, some useful quantity. That takes a useful concentration of sufficient available energy.

The larger collector can always be polished brighter, efficiency improved by some noticeable fraction. But increasing the area of any reflector incrementally increases the amount of energy collected.

Brad K. said...

JMG,

I thought the idea of a hybrid solar cooker and fireless cooker was somewhat missing the point. I know that last week your premise was to stop wasting fuel, to finish cooking by conserving the energy already collected by the pot and food. But if you use the solar cooker to bring your food to a useful point for your fireless cooker - move that food off to a best-efficiency fireless cooker, and heat the next dish or your tea, or bricks for warming the bed at night!


@ TG,

For the problem with an over-achieving solar dehydrator - what about draping the glass with a layer or three of cheesecloth, to reduce the amount of sunlight available? (Or set the solar cooker in front of it!)


@ DIYer,

What I recall of my social studies classes back in grade school, claimed that most aluminum production was powered by hydroelectric power. The book called aluminum "solid electricity". A hydroelectric generator would be built near a bauxite mine primarily to smelt aluminum, for cash from exports. (I think this was about early South American mines.)

Once smelted, I think aluminum takes less energy to melt and recast than iron and steel. So recycling scrap aluminum should be as available as other metal working, except. Aluminum begins to melt, and melts to a liquid, in a very small temperature range. Iron and most steel has a very broad range of varying degrees of plasticity between "solid" temperatures and "liquid" temperature - which makes blacksmithing possible. You don't get that with aluminum.

Copper and iron can be shaped, to some extent, while cold. Aluminum can as well - but becomes brittle and breaks much more quickly, in useful thicknesses.

JMG,

one of the icons I recall from pictures of the Great Depression was the tin can. Used to cook meals, boil coffee (no sissy stuff about having clear liquid with all the 'grounds' filter out!), and, flattened, to fashion about anything you might apply thin metal to, from gadgets to patches for mouse holes in the wall and floor and holes in the roof. Has no one used beer cans to fashion a solar reflector? Could Green Wizardly lend a new connotation to Bud Light?

Me said...

John, hello from a long time reader, Dan, who made the trek over to Cumberland back in March 2010. Now in India!

I had a question, although I apologize for its irrelevancy. You had spoken at length about martial arts and meditation when we had met. I think many people would be interested in your beliefs and research into the realm of meditation, and which form(s) is (are) the most beneficial from a mental and physical standpoint.

The concern I have is the same that we struggle with in the realm of martial arts, and in the prospects for our future energy-based economy. Getting a stamp of approval from a "most authoritative industry organization" could actually be a red flag.

All the best to you.
Dan

sebzefrog said...

Being french, I am culturally compelled to add my two cents to a
discussion about food. One could say that being french I am
culturally compelled to add my two cents about ANYTHING...
Anyway...

While reading an old book of recipes, made for "the perfect
housewife", I ran into an interesting fact. This book was pre-WWII,
and was describing several recipes of the kind our dear Archdruid was
telling us about in the previous post. Earthy, without the convoluted
"grande cuisine" touch of nowadays. This book was directed to young
girls as a textbook for their cooking classes. Cooking was part of
the regular teaching girls would receive in french school back then.

In this book, the point was made that in order to become an
accomplished housewife who could take good care of her home, one had
to learn not only to cook from scratch, but also the art of turning
leftovers into an enjoyable meal. Throwing them away or letting them
waste was the mark of a poor tender of the house.

This art relies on some few tricks and recipes, and lots of
imagination. But it also relies on a respect of the food that we can
sometimes tend to forget and puts some old rules in an interesting
context.
Learning to carve a chicken for example becomes more than a party
trick to impress your guests at thanksgiving. It is a little craft
that allows you to minimize the amount of chicken wasted. Serving
yourself from the middle of the plate of "gratin" is rude not out of
some arbitrary rule, but because it tends to leave out a plate that
looks more like a battle field than a dish you can serve again later,
when the guests are gone.

When one thinks about it it is obvious that in order to maximize the
efficiency of cooking, one option is to decrease the amount of
waste. And to me, even before we have to turn to solar ovens, we will
have to re-learn to eat everything that is available. Arguably it is something that we should be doing no matter what...

Maybe I am just pointing out the obvious. But a section of my personal experience makes me think that maybe not. In this
context a question that I find good food for thought is "How many
people could have been fed out of what ended up in my rubbish bin ?"

sebzefrog at hotmail.fr

Henry Warwick said...

an adjunct to the solar cooker: the haybox.

It's a box tightly filled with hay. You get the pot of food up to some crazy temp, and then take it off the fire and put it in the haybox, and seal it over. Come back a few hours later, and the food is cooked - the heat didn't leave thanks to the insulation, so the food continues cooking.

It's like a thermos / Dewar's bottle. Same effect. Heat it up and let it go - the insulation prevents heat loss, so the food continues to cook.

Hayboxes are very popular in parts of Africa, where fuel is scarce...

Cherokee Organics said...

Hi Brad K,

You write "Yes, it does seem sad. One question - at what point are you able and willing to abandon, as a community, the rule of law?"

I don't think that it was the Archdruid's intention to incite illegal activity by this particular observation. I think that you may have misinterpreted this.

The rule of law is only adhered to, if the community can rely upon or alternatively fears it's enforcement.

It's essentially a community contract, which historically can be changed at exceptionally short notice.

The legal system (and it is a legal system and not a justice system) is strongly concerned with property rights.

There are certainly other methods to organise these property rights and many people have run afoul of change.

I suspect that any transition to a new system will be difficult, force individual compromises and also force unusual mutually beneficial relationships upon us all if we are to work through such times.

Good luck!

Hugh Walters said...

While we are living lives of "austerity" - which is being marketed to us by the MSM, do you think Al-Gore will be doing the same?

Meanwhile China is building 2 coal fired stations per week. I doubt they will be living in shacks.

Unlimited exponential growth is simply not possible on a finite planet. However, our financial system *demands this* of us. Moreover, it funnels money up to the richest in society; leaving the majority to live in "austerity".

We need an end to the current insane debt/currency system, as much as we need better energy solutions. Moreover, if things were spread a bit more equally, I doubt there'd be a need for so much "austerity" - all the while 20,000 people at the Cancun environment conference eat 5 course meals, jetting around shagging hookers.

Brad K. said...

Cherokee Organics,

I couldn't agree more completely - and that is why I responded to Kevin's comment with that concern.

The topic of asset allocation seems more fluid to some than others. I personally think that 'easy' answers mean that the implications haven't been realized.

My concern is that the randomness of individual property ownership is less likely to suddenly deprive large numbers of people of life-supporting assets - the way streamlined, centralized government or community control can.

In the description of setting up The Farm, it was claimed that at basal community survival level, communal ownership of all assets is optimal. As the community survives and acquires the assets, though, it is private ownership that accelerates growth and advancement. I submit that The Farm included some experienced and very wise leadership, to use the resources they had as wisely as they did. Not every group and community can claim such expertise and wisdom, nor a dynamic that lets the expertise and wisdom do the leading for the benefit of all.

My suspicion is that the coming decline will be quite chaotic, and that any national or community approach will be more likely to cause vast unneeded and irreparable harm. Say, for example, spending national resources to enable large banks to sustain modern debt structures rather than actually expecting them to abandon destructive practices. Or maybe seizing abandoned buildings to dump undesirable folk that makes them more available for neglect and exploitation.

Oh, I am sorry. 'Dump' doesn't sound much like 'make available for the homeless'. But actively moving people from where they subsist to a designated area where rules that govern the 'real' community members aren't in effect, that sounds a lot like dumping to me.

Gobs said...

Others would disagree with your position on efficiency of solar panels.

http://www.newton.dep.anl.gov/askasci/eng99/eng99553.htm