Even if the world's political leaders can't agree to cut carbon emissions, they have agreed to spend more money on new technologies that could achieve the same goal.

The Mission Innovation initiative will see 20 countries doubling investments in clean energy research and development over the next five years. Meanwhile, a separate effort led by Microsoft billionaire Bill Gates, Facebook founder Mark Zuckerberg and other tech CEOs called the Breakthrough Energy Coalition, will solicit private investment to fund programs.

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All told, the public-private green fund will boost spending on early-stage clean energy companies in areas such as electricity generation, transportation and agriculture by $20 billion.

But which technologies need money the most?

One expert says it's better not to make an incrementally better windmill, for example, but instead invest in something that would really revolutionize energy production.

“A lot of the innovations that are going to happen are things we don't now about yet," said Laurence Blandford, international director for the Center for Clean Air Policy in Washington. “They are in the minds of scientists and engineers. My message would be to look for those technologies that have the potential to be transformational in the future."

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Developing energy storage would be a biggie.

Storage is critical to boosting renewables from their current level of 20 percent of the world's energy output, according to Brian Steel, co-director of the Cleantech to Market program at the University of California, Berkeley's Haas Energy Institute.

“How do you store energy from a sunny day and use it on a cloudy day?" Steel said. “Energy storage continues to be the Holy Grail for a number of these energy solutions."

Steel's program at Berkeley takes early new technologies — many from university labs or startups — and partners them with long-established businesses to help them get off the ground. Sometimes the best ideas don't make it to market, and that's where the new energy initiative could make a difference.

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“It's very difficult to move things from concept in the lab to independent commercial success," Steel said. “Traditional money (such as banks) wants to see a certain amount of commercial viability before they get involved, but entrepreneurs are saying how can I demonstrate it without the money to support trials and pilots."

Steel says it's hard pick the next breakthrough energy tech.

“There's no place where a little squirt of money will make a big difference," Steel said. “We are talking about global technologies that are decades in the making."

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Solar power has come a long way in the past two decades, and is now become an affordable option for many homeowners. Despite these lower costs, the efficiency of solar panels is still between 12 and 22 percent. Boosting solar efficiency beyond 30 percent would be a game-changer and allow the cost of solar power to drop throughout the developing world where energy costs are high.

It would also allow homeowners and businesses in cloudy or low-light areas to run on solar, according to Tom Kimbis, vice president for executive affairs at the Solar Energy Industry Assocation in Washington.

Kimbis says that so-called third generation solar technologies that layer semiconductors to boost power efficiency could be what Gates and others are after.

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“Who can come up with a breakthrough in the next generation that will make it cheaper?" Kimbis said.

Figuring out how to better manage the flow of electricity from solar panels to homeowners and utilities and each nation's electric grid is another priority, Kimbis added.

For example, Germany was forced to dump some of its wind power last summer because it produced too much and the nation's electric grid couldn't handle the flows.

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“If you have better grid monitoring and intelligence, would have controls over keeping the lights on," Kimbis said. “They can monitor electrons flowing in and out of your home better. They may be able to store it. Not in huge banks somewhere, but maybe a microgrid system."

Will these efforts by private companies and academic labs to come up with new kinds of renewable technologies make a difference?

Experts say the drive to cut carbon emissions will still need the help of political leaders to push policies that penalize the use of fossil fuels. Otherwise, people will continue to use cheap coal, oil and gas.

“We live in a global climate system," Steel said. “So unless there is a collective public acknowledgement between individual action and public consequence, you can't have an appropriate solution."