Solar-Powered Cars? Clean Energy Hype Needs a Sober Dose Of Reality
By William Banholzer
Toyota Prius (Photo credit: Wikipedia)
The distinction between what’s possible and what’s practical is sorely missing from the clean energy debate today.
People are waiting for a miracle that will allow them to rely less on petroleum without really having to change their lifestyle. They skim news headlines, over-interpret advertising slogans, and in the end, fall for the clean energy hype.
This became quite clear to me at a recent social event when a highly educated and articulate acquaintance of mine announced that she was buying the new “solar-powered” Toyota Prius. She believed the solar-paneled roof would power the entire car, not just the ventilation system, as is actually the case.
I can’t blame her for thinking that way. There are few people who truly understand or appreciate the tremendous energy concentration of gasoline. The heat of the sun certainly feels powerful, and we all know that sunlight can be converted into electricity. So unless you have a framework for comparing one type of energy to another, it seems plausible that a car could run solely on the sun’s energy.
In reality, it isn’t practical and it never will be. An entire Prius rooftop covered in photovoltaic cells could only generate a tiny fraction of the energy needed to propel the car 33.4 miles — the average distance an American drives in a day.
There’s a reason why cars that win the World Solar Challenge are built like small, flat spaceships on bicycle wheels. The roomy sedans and SUVs that we love to drive are simply too massive to be powered by the sun.
I respect that solar energy plays a significant role in the clean energy economy, especially when used to supplement power for buildings and homes, which have large flat surfaces for capturing the sun’s rays. It’s even great for providing energy to electric-car charging stations.
But a solar car, on its own, is not practical.
Biofuels suffer from a similar hype problem. Over the past decade they’ve been positioned as the solution that will not only solve the country’s energy problems, but will do so while maintaining or even improving our quality of life. Such promises are unmet today.Consider cellulosic ethanol, arguably the most hyped of all biofuels. There were approximately 6.6 million gallons of this renewable transportation fuel available in the U.S. in 2011 — a far cry from the 250 million gallons mandated in 2007 by the U.S. Environmental Protection Agency’s Renewable FuelStandard.
The main problem: cellulosic ethanol isn’t cheap. A whole lot of energy and raw materials are needed to produce even a small amount of fuel.
It’s true that cellulosic ethanol can be made from a wide array of plant materials and even from garbage. And it’s true that these materials are sometimes inexpensive or free, such as beetle-killed trees in the Mountain West and municipal solid waste.
However, too much public focus on these opportunistic feedstocks has presented a misleading picture that free raw materials are widely available. There simply are not enough of these materials to supply what’s needed for significant biofuel production. Not to mention that the price would likely change as soon as the suppliers of “free” raw materials notice someone’s making a profit.
Even if the country did increase its bioenergy crops and started doing a better job of collecting agricultural wastes for use as cellulosic ethanol feedstocks, the cost of biofuel production is still higher than the market would likely tolerate.
I hear people talk about the prospect of biofuels reaching cost parity with oil. But parity is insufficient. The lowest-cost option will always win with consumers.
And that brings me back to my point: We need to be more grounded if we’re going to make progress on the clean energy front. Industry has an obligation to create a return on its investments, and history shows that money flows when the economics are compelling.
With this in mind, the clean energy conversation should center on practical improvements to materials and engineering. On the transportation side, we can rely more on diesel fuel, especially in combination with particulate filters that remove soot. High-efficiency internal combustion engines combined with lightweight materials can dramatically increase fuel efficiency in cars and trucks.
Meanwhile, wind and building-integrated solar modules with high efficiency photovoltaic materials can supplement our electrical generation capability, as stricter building codes and improved insulation can decrease the energy used to heat and cool buildings.
And let’s put more emphasis on turning biomass into electricity, not just liquid biofuels. The former is a far more economical option, but rarely gets public attention.
As a country, we have to be more rigorous in separating energy the hype from the practical solutions that can improve our use of valuable energy resources. Our path to a clean energy future must be charted with pragmatism or we risk getting lost along the way.
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