Aperture (A follow-on to The Hydrogen Humvee and Other Fairy Tales)
Sunday, June 8, 2008 at 1:47PM This brings us to the subject of aperture. This is the concept that anything powered by renewable energy requires a certain amount of area exposed to the sun, or wind, or water, to collect enough energy to operate. The reality is that switching our present methods of life over to a renewable fuel won't work. The energy bloated lifestyle we live can only be supplied by tapping the hundreds of millions of years of accumulated energy trapped in the coal beds and oil fields under the earth. The hydrogen Hummer is only the most blatantly misleading example of renewable energy use. Still, it is only slightly beyond most of our technology in its unsustainability. Such wishful thinking extends in more subtle ways throughout the renewable energy industry.
Think about a normal kind of energy consumption, such as burning fifty gallons of #2 fuel oil in December to heat your home. Each gallon contains about 132,000 BTUs of heat energy. Burned in a very efficient boiler, you would get around 85% of that into your house, or 112,200 BTUs. Fifty gallons would be 5.61 million BTU’s. What kind of south facing windows would you need to collect that in December in northern New England? An unshaded south facing double glazed window in Vermont allows in 480 BTUs per square foot per day in December, on average, or 14,880 for the month. To get your 5.61 million would require a wall of windows 38 feet wide and 10 feet tall, with enough mass behind them to store the incoming energy for a matter of days. Let’s say you wanted to keep your house at 65 F and had barrels of water you could get to 110 F in the sun. That would require roughly 15,000 gallons of water, or 272 55-gallon drums. You could also think of it as a 5 foot wide box 10 feet high running the length of your 38 foot wall. A tough retrofit for your average American house.
And, of course, making these windows takes energy, as do the barrels or the 38 foot solar swimming pool.
You could do as many people do up here in Vermont, and burn wood. It is a direct use of biomass, and can be done sustainably. A cord (128 cu. Ft.) per acre per year is about what you can get over time. Most hardwoods have between 20 and 25 million BTUs per cord. Call it 23. An average woodstove will get about 60% of that into your house, or 13.8 million. So, you would need 0.4 acres of decent hardwood forest to equal that 50 gallons of oil and get you through December. In 2002, 5.2 billion gallons of heating oil were sold to 6.3 million households in the Northeastern U.S. (EIA) That is the equivalent of 25,367,000 cords of hardwood, or the same number of acres of hardwood forest, carefully logged. Coincidentally, 25 million acres is roughly the amount of hardwood forest we have in the northeast. It would take every square acre we have, meticulously managed, to produce the heating energy equal to the oil we now burn in our homes. Of course, this doesn’t include the heat energy we use in the form of natural gas or propane. It doesn’t include the heat energy we use in our office buildings, stores, and factories. We clearly have a solar aperture shortfall in the firewood department.
This is just one example of the non-sustainability of our present energy use. I could take any aspect of our society, from transportation to commercial electrical use, and apply the same analysis to it.
Some well-informed students of solar or wind power may counter that we do have plenty of roof area for photovoltaic modules in this country, and enough windy places to power our present system twice over. True, in the abstract, and for electricity only. In reality, windy places are not always located conveniently to large population centers, and the wind doesn’t blow according to our electrical demand schedules. Solar power follows our peak demand curve better, but not perfectly, and not on cloudy days. Our society, as it is presently organized, needs dispatchable power, power that is available at the turn of a knob, when we need it and in the exact quantity we desire. Dispatchable power requires stored energy, either fuel or water behind a dam. For fuel, we are talking about biomass, which brings us back to the forest acreage problem. What about hydro? According to the National Hydropower Association, perhaps the most optimistic source one could find, hydroelectric power accounts for 8-12% of our present electrical demand, with 104 gigawatts of capacity. The NHA estimates that this could be expanded by 70 gigawatts if all environmental restraints were laid aside. So, best case scenario, hydroelectric power could handle 20% of our present demand. Generally speaking, a stable utility system using both variable and dispatchable power can only tolerate about 20% variable, the reverse of the percentages we could face. If we consider a renewable future where hydroelectric power is our major dispatchable source of electricity, then we would need to limit variable sources such as wind and solar to 20% of that, or 4% of our present consumption. If we abandon all environmental concerns about damming rivers, and have the economic and societal wherewithal to build the dams, our future electrical capacity would be limited to just under a quarter of what we use now.
We have a society that is dependent upon an artificially large solar aperture. Since we have a fixed amount of surface area on the earth, one might call this a time-distorted aperture. What we are taking advantage of are the millions of years of sunlight that were absorbed by algae, most recently during the Miocene period, 12 million years ago. As James Kunstler pointed out in his excellent book “The Long Emergency,” one brief squirt of charcoal lighter fluid is equivalent to some primeval plant absorbing sunlight for seven years. Taking the period from 1859 to 2059, we will have burned through roughly 200 million years of oil and gas production in about 200 years, a million to one ratio.
The conclusion I come to from all this is that we need to calculate our available, sustainable, practical solar apertures on a local and regional basis. By solar I mean all those energy sources we derive from natural processes: direct solar, wind, rivers, tides (ok, that's lunar), ocean waves, and biomass. Then we need to plot a path from our present modes and quantities of energy consumption to those that match the available aperture.
I have to say that almost all our present efforts towards sustainability are laughably weak compared to the problem. We replace light bulbs and buy hybrid cars when we need to fundamentally redesign our entire electrical grid and reorganize our population distribution. It's like preparing to jump out of a plane with a cocktail umbrella in each hand and focusing on the design of the cocktail umbrella. We're in for a sudden jolt unless we start thinking bigger.
Reader Comments (7)
"a cocktail umbrella in each hand' that's a great image.
Hi, H!
What about nuclear power?
I know nobody likes it here, but it's been working fine in France for almost 50 years, without any (known?!) incident and represents 80% of the consumption of electricity in France. EDF even sells electricity (at peek demand periods)to all France's neighbours.
Areva, the French nuclear company (ever saw their ads on TV here?), by the way #1 in the world, is getting bigger and bigger contracts in the US for building plants and cleaning nuclear waste and so on.
We now know how to (partially) recycle used plutonium and, although there is still some % to store away for a very long time, it seems to be working fine.
What do you think and aren't we condemned to go that way?
By the way, a lot of ships and submarines are equiped with nuclear engines too...
Take care,
Hervé
Herve,
Nuclear has the same resource problem as oil, coal, and natural gas. There is only so much in the ground and as we extract more and more, our extraction rate must slow down. Likewise, as we try for lower grade reserves, the amount of energy it takes to get X amount of energy out of the ground goes up. Eventually it takes as much energy to get the stuff out of the ground as it actually contains, and the process is useless. Even with reprocessing this will happen. Any energy source that gets dug out of the ground is a dead end.
And, of course, it leaves us saying to our grandchildren, "We got the electricity, you get the waste. Take care of it for a few hundred generations, ok?"
In a previous essay I wrote about how just replacing our refrigerators and industrial motor controllers would eliminate the need for most of our nuclear capacity. We need to stop wasting before we start making more waste. Don't start juggling grenades till you run out of tennis balls.
MH
H, you have indeed made an excellent case for nuclear power. Especially for a new generation of reactors which can be fueled from existing nuclear waste.
Humans are remarkably inventive when necessity comes calling. I expect we will see a broad spectrum of technological response to the problem of energy supply. There is no shortage of energy in the universe or even on earth.
Heretic wins this time. There is or isn't a shortage of energy on earth, depending on how long homo sapiens sapiens wants to be around. Heretic's math is pretty good and supported by other academic projections of BTUs, fossil-fuel energy, biomass, hydroelectric and wind sources, as well as the faustian fussing with nuclear power. As with Deffeyes and Hubbert, there will be differences at the margins, but the main points are clear to those who want to see. We can't go on like this, which leaves two possibilities, gramatically speaking. Focus on either the "We" or the "go on." Without the kind of change that Heretic envisions (and I think he's an optimist), "we" won't be "we" indefinitely. "We" will be far fewer in number, or else gone bye bye. Far better is not to "go on" this way and better yet to work on global accords (no I don't have a clue about how to do this) that (1) define the problem reasonably well, (2)prevent wars over dwindling resources, and (3) work with the resources we have, technological and human, to come up with a blueprint for sustainability. If all of that could happen in time, then I might agree with Michael that the Earth's energy resources might be deemed "adequate." But outside of this rather utopian schema, there is a grave shortage of energy on earth. But as long as we all have a good latte in the morning and a food coop that tells us how well off we are, I don't see things changing ahead of calamity. (My latte was superb this morning, and I have to break this off before the Montpelier Saturday outdoor market wraps up.)
"The answer to a technological problem may lie in that context rather than in the technology itself."
One context is population level. If we had fewer people, we'd need less energy.
Lots of pessimism here, but it's easy to fall into that glass. I have not done the research, but it seems to me that the planet has many millenia of energy remaining. In addition to nuclear energy (fission and fusion), there's the energy in the earth's mantle and core to consider, although we don't have a good way to tap it yet.
While the earth has a practical limit on the number of people it can support, we can't pretend we know that limit. Past predictions have not been accurate. However, one thing is certain: the limit will be reached with great suffering and pain but energy will probably not be the limiting factor.
There. I've jumped into the half empty glass with you, but for different reasons.