"The challenge is one that is a radical one," he said. "It is finding an economical means of turning abundant but dispersed renewable energy into useful modern fuels."

Emphasising the limits to reserves of oil, natural gas and coal and the pollution those fuels cause, speakers at the environmental group's fourth annual conference said technology for solar and wind power was available or would be soon.

But the development of renewable energy was trapped in a vicious circle of high prices, low demand and small-scale production, they added.

Michael Langman of accountancy firm KPMG's economic research unit in the Netherlands, which wrote a Greenpeace-commissioned report on solar power in August, said energy from the sun was economically feasible but could not yet compete on cost.

"Electricity generated from solar panels costs four to five times as much as the electricity that's taken from the grid," Langman said.

"For the price to solar panels to become competitive, a breakthrough is needed in production of solar cells - and that breakthrough can only be expected if solar panels are produced on a much larger scale."

VICIOUS CIRCLE

Karl Mallon, Greenpeace's director of energy solutions, said politicians and business leaders could break the vicious circle by embracing change and leading the charge.

"The government can pull down the price, industry can push down the price," he said.

Wind-powered turbines would account for 13,000 megawatts (MW) of electricity globally by the end of 1999, Flavin said, adding that developments in lightweight materials, aerodynamics and electronics would boost that figure and bring down costs.

Solar power is a much smaller source of power at only about 160 MW a year, he said.

Global energy giants such as Enron and Royal Dutch/Shell have made forays into renewable energy, but Flavin said the technology was being driven by small and medium-sized companies.

But because the wind and the sun are available to all countries, the traditional power bases of oil-producing states would eventually break down, he said.

"Increasingly we are going to find that there is going to be an international competition to embrace and take advantage of the new technology," Flavin said.

"It's not at all clear who is going to be in the lead."

The problem of storing and transporting the power produced by wind and solar sources would be tackled once electro-chemical fuel cells - which Flavin called the silicon chip of the next energy age - were more sophisticated and widespread.