EYEINDIAN SOLAR FARMING-2

LAST WORD

Solar Farming

is the Future

Imagine a crop that can be harvested daily on the most

rocky, barren, acrid land ...

... with no fertilizer or tillage input and that produces no

Why not encourage ag-bio engineers to develop solar

harmful runoff or emissions. Imagine an energy source so

energy farms? We could investigate the use of road rights-of-

huge it has the potential to provide many times the energy we

way (the Swiss have done this) and levee slopes as installa-

could ever expect to need. You don’t have to imagine it—it’s

tion sites. In addition, I have read that plants grow better in

solar energy. Solar energy falls everywhere at the rate of a

arid climates between rows of solar panels, possibly because

horsepower per square yard (1000 watts per square meter),

of the concentration of rainfall, so how about symbiotic sys-

and it’s free.

tems of crops and solar in the same field? There must be

I think it’s time to recognize where our energy must ulti-

many other interesting possibilities for integrating solar ener-

mately come from, and speed up building for that future. Ag-

gy systems.

bio engineers can be an important part of that future in plan-

Solar electricity could help plug-in hybrids shift about

ning and developing what I call “solar energy farming.”

80 percent of the daily trip mileage to electricity for drivers in

Right now, it appears that the mainstream has realized

the United States. The cost per mile would be one-third as

that making fuel from food (ethanol from corn) is not a very

much for electricity as for gasoline (at ten cents per kWh and

good idea: first, because it raises the cost of food for poor

three dollars per gallon). I have read that a capacity increase

people around the world (is that morally acceptable?), and

of 20 percent or less in our electrical power system would

second, because present practice requires such large inputs of

handle this additional load.

fossil fuel energy.

Of course, critics say that solar energy is intermittent,

The emphasis now seems to be shifting to making liquid

and diffuse, and the biggie: “The sun doesn’t shine at night!”

fuels from biomass and plant cellulose, but a lot of work still

The greatest load on our current electrical system happens in

needs to be done to develop this process. Certainly the idea of

mid-afternoon in summer, when air conditioners are operat-

using marginal land, and utilizing wastes that are otherwise a

ing and when solar energy systems would be working just

nuisance or a hazard, is laudable, and we are going to need

fine. Solar energy could provide much of this peak load, and

liquid fuels regardless of how many plug-in hybrid cars we

we could supply a large share of our overall electrical needs

have. We should therefore pursue this alternative.

with solar before we would need to think much about energy

However, in the November 2007 issue of

Smithsonian

,

storage. Meanwhile, every hour of sunshine can reduce the

Richard Coniff pointed out that even if we could set aside

use of fossil fuel (and production of emissions). Solar elec-

41 million ha (100 million acres) for cellulosic ethanol crops,

tricity is expensive, but we already know the costs, and they

of the approximate 324 million ha (800 million acres) in the

might well turn out to be no more than the more exotic solu-

United States, we would produce only about one-eighth of the

tions that have been proposed, such as CO

sequestration

2

projected U.S. energy consumption in 2025.

from coal-fired plants.

By my calculations, the amount of biomass energy pro-

After several tries, Congress has finally extended the

duced by an acre of corn in a season is less than the solar

solar tax credits. We need to do more to build a solar infra-

energy falling on that acre in one day. That is less than one

structure. On the day the last barrel of oil is pumped, will we

percent efficiency. Photovoltaic systems can be 15 percent

be ready?

efficient, and concentrating solar thermal plants can be about

I believe that engineers are generally believed to be hon-

30 percent, and they don’t need to compete with crops for

est and accurate. We need to also be informed and articulate

land.

about important issues such as this.

ASABE member William H. Peterson

is associate professor emeritus, Department of Ag-Bio

Engineering, University of Illinois, Urbana, USA, whpeters@illinois.edu.

RESOURCE     April/May 2009

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