Investors in alternative energy are confident entrepreneurs will find ways to drum up finance without deepening the global credit crisis.

Many people fear that as many alternative, low-carbon energy sources are more expensive than gas and oil, developing them will add to the current economic problems, but investors say projects will be aided by private capital.

"In clean technology I think there are 1,500 venture capital funds -- out of that something is going to happen which will fundamentally alter the corporate landscape," said John Browne, a former chief executive of oil major BP and now a managing partner at private equity firm Riverstone Holdings.

"There are many ways of doing that without creating a financial shock to the world," Browne said at a renewable energy finance conference in London organised by the World Energy Council and the Financial Times.

The failure of Lehman Brothers , the rushed sale of Merrill Lynch and the U.S. government bailout of AIG this week have all added pressure on the global economy.

However, governments, which are leading the hunt for energy alternatives, remain deeply concerned with energy security and climate change. Recent issues have been Russia's conflict with oil-transit country Georgia and the rapid melting of Arctic sea ice, which scientists say is at its second-lowest recorded level.

Energy prices will remain volatile and energy security will stay at the he top of the political agenda, said Browne.

Browne said he expected energy efficiency technologies to be "central" to efforts to fight climate change and would be led by government policies, such as carbon pricing.

Better efficiency would cut the bills for companies and households when fuel prices are high.

Cost cuts will be key over the next 20 to 30 years in the race of low carbon technologies to join fossil fuels in a changing global energy mix.

Rene Umlauft, chief executive of the renewable-energy arm of German engineering firm and wind turbine manufacturer Siemens, said costs would fall in offshore wind power -- a sector with technological and grid-connection challenges.

"The whole industry is moving very fast on the learning curve and costs will go down dramatically," Umlauft said.

A diversified energy mix would help keep the lid on costs, executives told the London conference.

"We must keep ideology out of our choices," said Pierre Gadonneix, chief executive of French utility EDF , who said the supply mix must include hydropower, nuclear, wind and high-efficiency coal and gas.

Shaving costs off new technologies and improving the efficiency of old ones will require extra funding for energy research and development, which in the United States had "dwindled almost to irrelevance", said Susan Hockfield, president of the Massachusetts Institute of Technology .