From his early days as a West Point economics professor, when he wrote papers on the U.S. military's role in securing foreign oil supplies for America's, retired Gen. Wesley Clark has seen energy issues in the light of global politics.

The former NATO supreme allied commander continued the theme at the Solar Power International conference in San Diego on Tuesday. He called for a "long-term fight" to meet the energy challenges that the country first grappled with in the 1970s and still face today.

"All of us together have to pull for the long term," Clark said in his keynote address to a packed conference hall. "This is not about one company's profits. It's really about America's national security, That's what it was in the 1970s, and that's what it remains."

Despite the ongoing financial crisis now gripping global markets, Congress' long-awaited passage of an eight-year extension of solar-power tax credits should help the solar industry weather the economic storm, Clark said (see Lawmakers Approve Energy Tax Credits, Bailout.)

His comments echoed those of California Gov. Arnold Schwarzenegger, who pushed for increased investment in green energy and technology as a way to counter the ongoing financial crisis at the conference Monday (see Schwarzenegger: Solar Can't Be Stopped).

But Clark said that solar's victory will have to be followed with better and long-term government incentives for a host of other renewable-energy sources, such as wind power, to meet the nation's energy challenges and to combat the threat of global warming.

"That's where we have to move, regardless of what the price of oil is today or tomorrow in the market," he told reporters after his speech.

Oil has fallen from all-time highs of more than $140 a barrel this summer to as low as $80 a barrel in recent days – although it's still higher than prices of $60 per barrel and lower in 2004 and 2005.

In the long term, the price of oil will continue to rise as production fails to keep up with ever-increasing demand, he said.  "The future's very clear," said Clark.

Solar, while flush from its recent victory in Congress, could use more government help as well, he said.

"I think we've really got to work for distributed generation, for net metering without restrictions throughout America," he said. "I'd like to see solar panels atop every strip mall in America. There's no reason not to do it."

But while Clark spoke of " ;energy independence" as the overarching goal for America's renewable-energy industry, he told reporters that complete independence from foreign oil is probably unrealistic. "We just want to have the security of our supplies," he said. "We want to be able to avoid the kind of lurching back and forth, in terms of foreign relationships that are not otherwise in our national interest."

Similarly, he said that increased domestic oil production should remain "part of the equation" for an energy policy that should tackle energy efficiency and conservation, as well as developing both new and established energy sources.

"We in the renewable sector shouldn't take on ourselves the immediate burden of replacing all other energy sources," Clark said. He added, as a light aside, "Let's give ourselves five to 10 years at least."

Clark also pointed to "clean coal" technologies that haven't yet commercialized, but that could hold promise for negating coal's oversized role in the emission of greenhouse gases.

"I think we can do a lot with coal, if we can clean it" and capture its carbon-dioxide emissions, he said. "With the right incentives and development, maybe there's a future for coal gasification and liquification."

Cleaner-coal technologies are controversial among environmentalists, who argue that mining prevents coal from being clean, even if technologies to capture and store carbon dioxide prove effective.

Even though he supports the technologies, Clark added that fossil fuels such as coal should be taxed, and that emitters should be subject to a carbon cap-and-trade system.

"The public utilities that burn coal, they see this as inevitable," he said.