By Onell R. Soto
Friday, November 12, 2010
If you’re thinking about going solar, well, in a way, you already have.
Most of the energy we use on Earth was created by the sun. Oil, coal, natural gas, wind, hydropower, even the heat from a wood-burning stove. (Big exceptions are nuclear and geothermal power.)
By relying on fossil fuels, we’ve built a civilization on ancient rays of the sun.
Stephen Mayfield, a scientist at the University of California San Diego, is working on how to transition to harvesting sunlight falling on the earth now into energy that can power the future without increasing greenhouse gases such as carbon dioxide, or CO2.
He’s doing it with algae — the tiny organisms that turn fish tanks green.
This comes after a career focused on the genetics of algae and the founding of a biotechnology company that used algae to make lifesaving therapeutic substances.
Now director of the San Diego Center for Algae Biotechnology, Mayfield discussed algae and why it matters.
Algae uses photosynthesis, the process of turning sunlight into chemical energy, but it’s different from plants because it lives in water, where the amount of carbon dioxide can be increased to boost production. That’s good because it takes greenhouse gases out of the air, even if they end up back in the atmosphere when algae fuels are burned.
Q: How do you get that extra CO2 into the water?
A: You can actually take it and pump it in there, you can bubble it in water, and as long as the pH is set right and there’s the right kind of water chemistry. … And can we get this out of the air and pump it into the water. You can get it from smokestacks, from coal-fired power plants, you can get it from cement kilns.
Q: How can algae help turn sunlight into something we can use?
A: What we need is chemical energy. Chemical energy could be food, like corn, could be sugar. But petroleum is also chemical energy.
Sunlight is energy, but it’s not in a form we can do things easily with. It sort of lands on the earth and reflects back into the heavens and turns into heat, but it’s hard for us to grab it and do anything with it. We can’t store it, for example. But if we can turn that light energy into chemical energy, we can store it, we can ship it, we can do all those things.
Q: Why do we have to worry about alternative fuels now? Isn’t there enough oil, coal and gas to keep us going for decades?
A: Of our known reserves, what do we have left? About 37 years of our liquid fuels, about 40 years of coal on top of that. About 100 years, that’s kind of an alarming number when you think about it. It means we’ve burned through half of our supply of hydrocarbons. …
The rest of the world, China and India, want to live the way we do, and in the United States we use 25 percent of the world’s petroleum every day and we’re 5 percent of the population. … The whole world cannot live like Americans. … There’s not enough energy on the planet to do that. So something has to give, and what will give is the price of energy. It’s got to go up.
Q: How does algae development fit in with our infrastructure of refineries, roads and internal-combustion engines?
A: The most important thing algae does is the oils that algae makes are fungible. That means they’re drop-in replacements. We can take algae oil, and with very simple conversions, we can pump that stuff right into an oil refinery and we can crack that into gasoline, diesel and jet fuel. And we’ve already done that. …
Q: Wouldn’t it be better to simply drive electric cars?
A: The problem is the vast majority — 92 percent of the electricity we generate in this country — we generate by burning coal or natural gas. All a natural gas is doing (is that) you’re putting pollution out at the power generating station and then you’re pumping the electricity to your car.
Second, you cannot fly an airplane or drive a truck (on batteries). There are no electric trucks, there are no electric airplanes — because the energy density of a battery is only 1 percent of the energy density of liquid fuels. Electric works OK for small utility vehicles. But it doesn’t work for heavy machines. It doesn’t work for boats. It doesn’t work for planes. It doesn’t work for trucks. So we’ll never get rid of liquid fuels.
Q: What role are San Diego companies and institutions playing?
A: San Diego has become the epicenter for algal biotechnology. Mainly that’s due to the fact that there were a bunch of us here, at UC San Diego and Scripps Oceanography and Salk and Scripps Research Institute etc. that were working on algae. … San Diego is very much a biotech hub. There are venture groups here. We understand how to build startup companies. … The algae expertise was here in biology. The venture money was here. The startup entrepreneur spirit was here. In San Diego. This is where all the algae bioenergy companies set up. I started one. Sapphire Energy. … Same with General Atomics, same with Synthetic Genomics.
San Diego was the nucleating site for algae bioenergy. Now we’re the biggest hub in the world by a long shot.
Q: Will companies move out of town as they grow?
A: The research and discovery is going to stay here because you need the university, you need the venture (capital), you need the entrepreneurs that are going to stay here in San Diego.
But certainly the production facilities are going to go other places. … They’re going to go to places where you can get land cheap, where there’s a lot of sunlight. You just can’t think about doing big-scale algae production here in La Jolla. Land is just too expensive for that. But we can think about it in the Imperial Valley. That’s a fantastic place for it.
Q: How much sunlight hits the earth? How does that compare to the energy in our oil, coal and gas reserves?
A: Those numbers, we put those into terawatts (a measure of energy), terawatt-years, so we can compare apples to apples. Total energy consumption in the world today is 15 terawatt-years, that’s all electricity, all petroleum, all nuclear, you name it, that’s what everyone uses.
About 86,000 terawatt-years of sunlight falls on the earth any given year, that’s 6,000 times what we can use. … The vast majority of it gets reflected back or gets turned into heat and dissipates. The trick is, how do we capture that?
And that’s what photosynthesis is. Photosynthesis is how the planet captures solar energy and saves it as chemical energy. What petroleum is, what coal is, what natural gas is, that’s solar energy that hit the planet millions of years ago. Plants converted that into chemical energy, those plants then got covered over, by dirt. …
So all of the energy we use, all of the energy we think about pulling out of the ground and burning, all of that — ancient photosynthesis.
Source: San Diego Union-Tribune