Transportation is Achilles' heel of green energy efforts

In America’s efforts to go green, our Achilles’ heel is transportation – as cars, trucks and buses represent 29 percent of U.S. energy use, according to renewable energy expert Gary Dirks, director of LightWorks at ASU.

Whenever U.S. officials talk about finding ways to end our reliance on oil, such as the current reaction to the massive Gulf of Mexico oil spill, we need to take a realistic look at how we use oil and what our available alternatives are, Dirks said.

For example, in our energy future “nuclear, solar, hydro and wind energy all will have growing roles in electricity generation, whereas the importance of coal and oil will decline,” Dirks said. “But when we want to move a car, a truck or an airplane, there's really only one way to do it – get the stuff out of the ground. Oil remains a relatively cheap source of energy that is so convenient, its use overrides its considerable drawbacks in terms of air pollution, environmental concerns and national security.”

So what can the United States do to end its messy addiction to oil while remaining a mobile society?

“In addition to a long-term transportation energy plan that does not include fossil fuels, we need a nearer term solution that can take us from the traditional internal combustion vehicles to tomorrow’s advanced fleet,” Dirks said. “That future should include the Sun.”

“There are techniques and nascent technologies in the works that will take carbon dioxide, water and sunlight and combine them in such a way to generate fuels for our cars, but today they are too expensive,” Dirks said. “More research and development is needed to make these fuels a reality. That is why the U.S. Department of Energy (DOE) is sponsoring an energy innovation hub to make ‘drop in’ fuels from sunlight.

“The beauty of these fuels is that they don’t require production of any fossil fuel, which in itself requires energy and generates pollution, but are made from completely renewable, existing and abundant components – water, carbon dioxide and sunlight.”

The process is similar to photosynthesis, by which concentrated solar energy is used in conjunction with carbon dioxide and water to create hydrocarbons. In addition to creating combustible fuels such as methanol and ethanol, additional processing can yield more traditional fuels such as gasoline, diesel and jet fuel.

“The fuels that result from these processes will look, feel and perform just like what we pump into our cars today," Dirks said. "They will use existing refineries to prepare fuel blends and existing gas stations to deliver the fuel to today’s cars.”

But the new fuels will be carbon neutral and will not add to the buildup of greenhouses gases blanketing the planet. They also will help the United States move from an unstable source of energy produced far offshore, to a form of energy generated on our soil. Drilling will not be needed with these fuels. Increased security, cleaner air and new jobs will result.

The DOE Hub, along with several other ambitious initiatives involving both the near-term and long-term future of fuels, specifically looks at processes for making solar liquid fuels and bringing them to market in a developmentally rapid, 15-year time span.

“We need investments in the R&D phases of this technology to come not only from the government, but from industry too,” Dirks said. “And the new fuels will cost a lot more than the old fossil fuels they replace, at least initially. 

“Even with subsidies, the cost difference could be dramatic,” Dirks added. “Five dollars for a gallon of solar liquid fuel is a realistic short-term target, but it could be more. So, we need to ask ourselves, do we want to continue with what is convenient and economical today, or do we want to focus our efforts on what is the logical next step in our long-term energy future?”