Can a country that gets nearly half of its electricity from burning coal really get 80 percent of its electricity from "clean-energy sources" in less than 25 years According to Energy Secretary Steven Chu, the answer is yes if the U.S. cranks up its "innovation machine."

The top energy-related headline from the State of the Union speech last night was President Obama calling for the U.S. to get 80 percent of its electricity from "clean-energy sources" by 2035.

Steven Chu during a tour of an Energy Department grant recipient in December.

Obama said the U.S. should invest in technology innovation in biomedical research, IT, and particularly clean-energy technology as a way to perk up the U.S. economy.

Today, Energy Secretary Steven Chu held a town hall meeting where he took questions from those online and provided color on Obama's speech. The question of how "clean energy" is defined could be significant if Congress takes up energy legislation.

Chu said Department of Energy research programs can complement industry to accelerate development of cheaper forms of clean energy, opening up export opportunities for U.S. companies.

The budget that the White House will submit to Congress will call for $8 billion in research, development, and deployment in clean-energy technology programs, reported Energy & Environment News. That represents a one third increase in funding, which would be funded by subsidies currently provided to fossil fuel energies.

The budget also calls for creation of three new "innovation hubs" focused on different energy technologies. It will also seek to double the budget for the Advanced Research Program Agency-Energy (ARPA-E), which was funded through the stimulus program with $400 million over two years. (See PDF for details of budget proposal.)

Right now, renewable sources, including hydropower, solar, wind, geothermal, and biomass, make up about 10 percent of electricity production in the U.S., with nearly 7 percent coming from hydropower.

Chu said the White House's "working definition" of clean energy also includes nuclear power, which has no emissions during operation, and natural gas. Compared to coal, natural gas has about half the carbon emissions as burning coal, fewer air pollutants, and no mercury.

"Roughly speaking, right now, we are about 40 percent clean-energy sources in the way that you can define it. If you define it in a very strict way of no carbon emissions that includes sun, wind, hydropower and nuclear, we're over 30 percent," Chu said.

Even in that context, Chu admitted that getting to 80 percent by that definition will be ambitious. "Is it over the top, we can't achieve that No. We think we can achieve that," he said.

Technical advances can speed this transition along significantly. For example, the Energy Department has a goal of bringing the cost of solar photovoltaics down below the cost of fossil fuel-generated electricity.

"Imagine a world where that is true before the end of the decade," he said. "If we're the developers of this technology, this is a huge worldwide market and it will just take off."

Congress interested Last night, Obama said that the U.S. has had its "Sputnik moment" in seeing other countries, such as China, move ahead rapidly on science and technology, particularly energy. That line echoes a speech Chu gave several weeks ago, where he called on the U.S. to invest in more research and development.

"We are in a race. In my way of thinking, this race is much more important in terms of (U.S.) prosperity of not only five, ten years from today but next year and the year after that," Chu said. "This is an economic race to develop those (energy and energy efficiency) technologies the world will want and buy."

In terms of policy, though, it's not clear that enough members of Congress have an interest in addressing energy to bring an energy bill forward.

A legislative effort to cap carbon emissions from big polluters failed last year and Obama did not mention climate change or carbon emissions in last night's speech, focusing instead on the economic opportunity around energy technology. One of the ideas to advance energy legislation this year is to create incentives or mandates for more "clean energy," however it is defined.

Chu said that White House will need to work with Congress to hammer out a common definition. According to a fact sheet put out by the White House last night, so-called clean coal is also considered clean energy.

In response to a question, Chu said that carbon capture and storage, where carbon dioxide gas is pumped and stored underground, is "not a slam dunk proven thing" technologically. But he said the Energy Department and coal industry have a game plan for making the technology work, which will be needed for natural gas power plants in the decades ahead.