As diplomats from 200 nations gather this week in Marrakesh, Morocco, for U.N.-sponsored global climate talks, one likely topic of discussion will be better, cleaner and lower-cost energy technologies.

Raising financial support for new energy technologies is a major roadblock, particularly as private funding has declined. U.S. venture-capital equity financing for new energy and other clean technologies has fallen to $2.2 billion this year through September, from $5.7 billion in 2011, according to Dow Jones VentureSource.

To explore the challenge of financing new energy technologies, we spoke with Severin Borenstein, E.T. Grether chair in business administration and public policy at the University of California at Berkeley’s Haas School of Business; Jim Rogers, former chairman and chief executive of Duke Energy Corp. ; and Jesse Pichel, managing director at Roth Capital Partners in New York. Here are edited excerpts.

WSJ: What do you see as the most promising way to finance new energy technologies?

MR. BORENSTEIN: The good news has been the great technological progress in solar photovoltaic cells, wind power and storage, which has brought renewable costs way down. But the bad news for renewables has been the fracking revolution that has lowered natural-gas and oil prices to less than half the consensus forecasts of a decade ago. Innovative approaches to financing are important, but they can’t overcome the tide of fundamentals.