Solar, Stupid
Every day of class in my Science and Human Values class, a group of students informally presents a topic pulled from current events that is supposed to be relevant to the course. So far, of the dozen or so groups that have presented, almost half of them have been on the subject of alternative energy, specifically alternative fuels. Last thursday I heard this gem:
Biodiesel is great because, um, you get more energy from the fuel than you put into growing it, and it takes less energy to make than it takes to make oil.
Now maybe I didn’t quote my pensive peer perfectly, but a lot of what I hear is along the lines of 1) biofuels will cost less at the pump, 2) the storage and transportation issues that keep the sale of biofuels restricted to the agricultural heartland will quickly be dispensed with upon the arrival of Technology, 3) biofuels will somehow avoid the pitfall of being a resource that will (at best) increase in availability arithmetically, while demand for energy continues to grow geometrically, and 4) what we run our cars on will make or break global warming.
In comparing the efficiency of biofuel sources like palm-oil or switchgrass to petroleum, it’s often overlooked that oil (and coal for that matter) aren’t actually sources of energy, but rather stores of it. Ancient biomass is heated and compressed under the Earth’s surface, and over period of geological time it forms fossil fuels. The energy in this original biomass came from the sun, and the energy made available by biofuels comes from the sun too. Unlike fossil fuels, plants convert sunlight to chemical energy on demand with energy costs that give us a positive return, while the formative process of fossil fuels is completely obscured by history.
As good as this makes biofuels sound, they’re not going to satisfy the increasingly savage addiction we have to fossil fuels. In general biofuels aren’t as energy-dense as fossil fuels, and it seems they may require much more effort on our part to refine and process. But we must remember, both of these fuels are merely stores of solar energy, not sources.
Andrew C. Revkin, of the New York Times’ Dot Earth blog recently posted on the topic of solar energy as the best and last answer to energy demands, quoting Daniel G. Nocera, chemist and professor of energy at the Massachusetts Institute of Technology.
“All scientists ultimately believe solar has to be the answer,” he said. On Thursday, he laid out his “big idea” as a formula: “If you take sunlight plus water, that equals oil plus coal plus methane.”
One of the most interesting parts of Nocera’s presentation at the Aspen Environmental Forum was his predictions for energy consumption over the next half-century.
Dr. Nocera said human activities, in energy terms, right now are essentially a “12.8 trillion watt light bulb.” Our energy thirst will probably be 30 trillion watts, or 30 terrawatts, by 2050 with the human population heading toward 9 billion.
Finding other options is a huge challenge, he added. To illustrate, he provided one hypothetical (and impossible) menu for getting those 18 additional terawatts without emissions from coal and oil:
- Cut down every plant on Earth and make it into a fuel. You get 7 terawatts, but you need 30. And you don’t eat.
- Build nuclear plants. Around 8 terawatts could be gotten from nuclear power if you built a new billion-watt plant every 1.6 days until 2050.
- Take all the wind energy available close to Earth’s surface and you get 2 terawatts.
- You get 1 more terawatt if you dam every other river on the planet and reach 30.
As he summed up, “So no more eating, nuclear power plants all over, dead birds everywhere, and I dam every other river and I just eke out what you’ll need in 40 years.”
Then he turned to the sun, his research focus, which bathes the planet in 800 terawatts of energy continually. “We only need 18 of those terawatts,” he said. But the current level of investment in pursuing that energy, he said, isn’t even close to sufficient.
Check out the rest of the post here.
While I think Nocera may have overlooked the capacity for satisfying our needs with less energy through higher efficiency, ie Negawatts, I agree with his long-view approach to energy demands. Ultimately, yes, the sun is the root of almost all energy on our planet. If our energy demands continue to grow unabatedly, we will exceed the relatively quick-fix provided by fossil-fuels. Other options like wind, biofuels, geothermal, tidal, and nuclear power generation will surely help, but they too are limited in their capacity. For the demanding class 1 civilization solar really is the grandaddy of energy sources.
Instead of a chicken in every pot and a car in every garage, I want solar on every roof and bikes in every bungalow. Either that or a Dysonsphere.