I’m not exactly an energy policy wonk. So this semester I am sitting in on a very cool MIT course, the Physics of Energy, to try to strengthen my background in this area. I can’t transform all the equations they show on the board, but in terms of policy outlook, the class certainly seems to reinforce what I’ve already heard from a lot of other places. And so in honor of the Energy forum Discover is now sponsoring (eyes right, see sidebar), I thought I’d weigh in on the big picture version of what I’m learning.
Clearly, fossil fuels have got to be phased out, as quickly as possible. In terms of filling the gap, you then contemplate wind, solar, tidal, geothermal, nuclear, and so on–and the source with by far the greatest potential, and the fewest downsides, seems to be solar. There is a place for all of the others, of course. But nothing can ultimately compare to harnessing the central energy source into the planet for our own purposes.
As I learned in the Physics of Energy, every 47 minutes, the sun delivers enough energy to power all of our societies for a year–if it could be harnessed, anyways. To power the entire United States, meanwhile, one would theoretically need a solar array whose surface area is just a small fraction of the total size of Nevada–assuming the solar panels were 100 percent efficient, anyway. They aren’t even close to that; but the point is, the potential here is massive. The problem to get higher efficiency and lower cost for solar energy is technological in nature; but the potential upside is incredible–which seems to suggest that California did the right thing with a recent bill to promote solar.
Or am I missing something?
October 13th, 2009 at 9:28 am
The maximum *theoretical* efficiency of Photovoltaic is 60%. In practice, only very expensive ones are better than 10%, and even the 10% ones are very expensive. In addition, only a much small fraction of sunlight is harness-able, due to hours of day and weather.
I HIGHLY recommend the free book “Sustainable Energy – Without the Hot Air” – it is a very fun read, extremely interesting, and if you skip the footnotes and technical chapters, very short.
http://www.withouthotair.com/
He tackles the myth of the “little square” of solar panels, shown on a world map of what is necessary to power the entire world… And it seems like a very serious book in its numbers and methods.
I am very very much in favor of sustainable energy, but I admit this book has made me rather pessimistic on the actions currently done for it, and made me realize this requires a far far larger scale effort to actually work…
October 13th, 2009 at 9:37 am
Edit: I completely misremembered the number – The maximum theoretical efficiency is 30%, according to the book (and his reference..)
October 13th, 2009 at 10:02 am
Yes, one of the most important considerations is that energy conversion is rarely an efficient process. Let’s take photosynthesis in plants as the ideal. After all, photosynthesis has been evolving for at least a billion years and there are huge selective advantages to increasing its efficiency. Yet the final results are crummy; here’s what Wikipedia has to say:
“On a molecular level, the theoretical limit in efficiency is 25 percent[1] for photosynthetically active radiation (wavelengths from 400 to 700 nanometer). For actual sunlight, where only 45 percent of the light is photosynthetically active, the theoretical maximum efficiency of solar energy conversion is approximately 11 percent. In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in an overall photosynthetic efficiency of 3 to 6 percent of total solar radiation.[1]”
I think that beating Mother Nature in overall energy efficiency (remember, solar photovoltaic requires a lot of energy to manufacture) is going to be tough. My personal favorite among solar technologies is a genetically modified photosynthetic process.
October 13th, 2009 at 10:17 am
The most advanced plant has achieved 31.25% efficiency at the Sandia National Laboratories’ National Solar Thermal Test Facility. You can view more information here: http://discovermagazine.com/2009/oct/08-introducing-most-efficient-solar-power-in-world
At that efficiency level, we would have the capability to power the world every 150.4 minutes… (using only my basic math skills, which although could be incorrect you see the point). Though we would need land area much larger than the size of Nevada in this scenario, we wouldn’t actually be concentrating all our solar plants in one area, they would be spread across the globe.
October 13th, 2009 at 10:18 am
Also, just 1% of the suns energy hitting the Sahara desert could power the whole of Europe with clean energy. There are plans afoot to make use of this. The sooner, the better!
October 13th, 2009 at 10:35 am
The book Oded is referring to is fantastic and everyone who is interested in sustainable energy should read it. In fact, probably everyone should read it.
The biggest problem I have with solar is that covering earth with solar panels will destroy the underlying ecosystems. Deserts are one of my favorites, and they aren’t nearly the barren wastelands that most people assume they are. Even the Sahara harbors unique life that’s worth keeping.
Then there is the question of how limited the supplies of materials to make photovoltaic cells are and how environmentally costly the actual production of those cells is. All in all, solar looks like a dead end right now.
I think everyone should give another thought to nuclear. It’s the greenest, most sustainable energy we have right now.
October 13th, 2009 at 11:01 am
You forgot the limitations of the technology used to collect sunlight. For instance, even if you get a super efficient PV cell, how much raw materials (say, gallium) really exists with which you can make solar cells?
Or, say you build solar thermal plants in the Arizona desert to power California (this is really the most promising technology). To turn the turbines, you need steam, and water isn’t in great supply in the desert. Then you need to transport the electricity to where it’s needed. You can build very efficient power lines bringing the electricity in. But that sounds easier than it is. Too much or too little power relative to demand can cause brown outs or overloads. So the problem starts to get sophisticated.
Solar is a variable highly variable resource. The sun doesn’t always shine. As Steven Chu says in this article: “How do you maintain and run a reliable transmission and distribution system when you have variable power?” (See this Technology Review article for more info on the smart grid.)
Check out this article by National Review writer William Tucker. Conservatives are pushing for nuclear rather than the sophisticated high tech fixes. I have a theory that they are doing so for reasons of political economy (David Frum hints that this is the case in this in this post). If you look at the corporate powers benefiting from the smart grid and alternative energy (e.g., GE, technology, Silicon Valley) they are all in the pockets of the Democrats and they have bit of cash to support their interests… (By the way, I myself see nuclear as part of the solution, as long as it can be done safely and cheaply, which is not a foregone conclusion.)
October 13th, 2009 at 11:11 am
Lindsay, as you recommended withoutthehotair, I’m surprised you mentioned nuclear.. As the book shows, nuclear isn’t very sustainable as well… Unless the oceans reserves are used, and fast breeder method is used – both of which are unlikely right now… And even then, the reserves last for a thousand years, which to me personally doesn’t sound very sustainable…
Actually, if I wanted to be really futuristic and optimistic, I would suggest switching everything to nuclear right now, ASAP, which would be the cheapest option to get off carbon, and then hope the reserves last until fusion is cracked… But as the book said, it is downright irresponsible to assume that fusion WILL be cracked, and not a real energy plan….
October 13th, 2009 at 11:13 am
[...] Blogs / The Intersection « So Let’s Talk About Energy (By Which I Mean, Solar) [...]
October 13th, 2009 at 11:25 am
@ Lindsay,
Yours are excellent points and am glad you mentioned them, because that has been for me one of the major problems I have had with solar power. Moreover, contrary to what its advocates say, at best, it could only provide about 10% of our country’s energy needs. I know that leading climatologist James Hansen is rather skeptical of solar power’s potential impact too.
October 13th, 2009 at 11:28 am
Let’s not forget the difference between operating efficiency and total system efficiency. Operating efficiency — how much of the solar energy the facility turns into useful electricity — can be fairly high and we could still end up with low total system efficiency. That could arise if the energy costs of building and operating the plant and delivering its output to the end user are high. This is one of the tough problems with most solar energy. The best place to build it, in the deserts, has little water, which is necessary for most technologies. Getting water there costs energy. And the transmission costs are also serious. I’m not claiming that solar isn’t desirable — I agree that it’s our best long-term option. But it’s not going to be easy.
As far as nuclear, I’m optimistic about it technologically and pessimist about it politically. Just as we will never get rid of farm subsidies, we’ll never make much progress with nuclear.
October 13th, 2009 at 11:37 am
Erasmussimo –
Yeah I agree with your pessimism. Add on all the crazy, irrational fears of another Chernobyl and the political activists totally against it (fracking Greenpeace idiots), it will probably be a long time before it becomes a politically viable option. France gives me hope though: http://www.developpement-durable.gouv.fr/energie/anglais/politique-energetique.htm
October 13th, 2009 at 12:01 pm
It is about time all of the nuclear advocates start looking at the total process rather than just the relative safety of a nuclear power facility. We all know that failure to treat materials with respect can have deadly consequences.
Before we jump to the conclusion that nuclear is a “safe” alternative. we need to ensure that there is an air tight chain of responsibility from the mining operation, through transportation to the refining processes to the use and then the disposal of all nuclear materials. The part that most forget about is the mining, and the National Mining Association just loves that fact.
If you don’t believe that mining has wantonly spread nuclear toxicity from mining, I suggest that you move to Window Rock, NM and drink from rural water sources.
When you add the cost of such responsible action to the already soaring costs of nuclear, renewable begin to look very cheap.
October 13th, 2009 at 12:27 pm
The only real technology capable of generating electricity in large quantities now is nuclear. If only the public and politicians would get over their paranoia about all things nuclear and enact sound solutions like the pebble bed reactor. It’s insanely depressing that people don’t talk more about it.
October 13th, 2009 at 12:28 pm
Living in the high desert where the sun shines a lot, one thing no one mentions is how to keep the solar panels clean. No matter what their efficiency when brand spanking new, a nice layer of dust could cut that in half or worse. And you can get a nice layer of dust in a day, every day.
How do you clean solar panels? Like windows: soap, water, sponge, and squeegee. Same for the reflectors on concentrating collectors as for the photoelectric cells.
The water budget is going to be a logistic problem for all sustainable futures because the supply is already fully allocated or being polluted by existing technologies.
October 13th, 2009 at 12:36 pm
The other thing about nuclear, is that this is a global problem. We’re not only solving the problem for ourselves, but for the rest of the world aspiring to be middle class. Do we really want to have our solution to rely on nuke plants, and then turn around and give this solution to say, Pakistan? One day, the byproducts could get into the wrong hands.
October 13th, 2009 at 1:31 pm
Jon, proliferation is a problem that the whole world has been aware of since the 1960s. The Non-Proliferation Treaty, signed in the early 1970s, provides reasonable protection against proliferation to signatories. Unfortunately, the NPT is coming apart at the seams, largely because the USA bent the rules every time we saw geopolitical advantage to doing so. Moreover, the basic deal in the NPT was that the nuclear powers would reduce their stockpiles of weapons in return for the non-nuclear nations refraining from getting bombs. We didn’t even start reducing weapons until the 1990s, and the non-nuclear nations feel that they got a raw deal in the NPT.
October 13th, 2009 at 1:37 pm
…provides reasonable protection against proliferation to signatories…
I hope so… However, if I had the chance to pay marginally more for energy so the stuff is never produced in the first place, etc., I’d take it.
October 13th, 2009 at 2:14 pm
Back to Chris’s original point. We need a much more serious effort orders of magnitude greater than what is proposed now. We are on the clock with impending fossil fuel depletion and climate change. We need to move faster on on developing all alternative energy sources, nuclear, wind, solar biofuel etc.
For an excellent summary of the problem we face see Sharon Begley’s Newsweek article “We Can’t Get There From Here” .
http://www.newsweek.com/id/189293
October 13th, 2009 at 2:21 pm
Don’t forget “the fifth fuel.” The smart grid makes a lot more efficiencies possible, for instance, automated demand response.
October 13th, 2009 at 2:40 pm
(Of course if your idea of fun is blowing up low flush toilets, you’re probably not in the target market for this thing, and you might think it’s the worst idea since water fluoridation…)
October 13th, 2009 at 2:40 pm
Thanks everybody. I am learning more than in my class ;>. But I wish there was some way of getting more definitive about these efficiency and water use questions, as there seems to be so much disagreement.
October 13th, 2009 at 4:00 pm
Chris, for that, I again highly highly recommend the book, “Sustainable Energy – Without the Hot Air”. It’s a book all about numbers, buy a guy who values the numbers more than any agenda. I don’t remember him mentioning water in regards to biofuels, but efficiency is just about what the whole book is about… So, take a few hours and go for it
cause it’s a really short book
October 13th, 2009 at 6:03 pm
I wish there was some way of getting more definitive about these efficiency and water use questions
Well, if there was ever a place to get answers to these questions, you’re at it. They’re building a whole institute studying issues like these up the street.
November 15th, 2009 at 5:06 pm
[...] kicked off the day with a post on solar energy. I lonesome the awaiting over a year ago at Seed’s Next Generation Energy: [...]