BRUSSELS -- Energy chiefs from both sides of the Atlantic agreed to cooperate on hydrogen research on Monday, hailing the gas as the key to a pollution-free future and dismissing environmentalists' fears.
"Hydrogen is...the focal point in an energy revolution -- the hydrogen revolution," European Commission President Romano Prodi said.
"That simple element offers significant prospects for storing, transporting, and producing clean energy in the not-too-distant future," he told a conference in Brussels.
Hydrogen could be a way to wean the planet off fossil fuels and integrate renewable energy sources into the world economy, he said.
"Today, hydrogen looks like the best candidate, but its potential is still to be proven," he said.
U.S. Energy Secretary Spencer Abraham said the cooperation on research was just the start of "an international approach to achieving our collective hydrogen vision", with the next step a ministerial-level meeting in Washington in the autumn.
Hydrogen's proponents envisage a future economy which uses the gas -- which is present in water, oil, gas and coal -- as an energy store, with hydrogen-fuelled cars emitting only water in their exhaust.
"HYDROGEN NOT INHERENTLY CLEAN"
But environmental groups said a hydrogen economy would only be as clean as the energy used to create the gas and criticised both Brussels and Washington for failing to put renewable energy sources at the heart of their hydrogen policy.
"Hydrogen is not an inherently clean technology," said a joint statement from four environmental lobby groups.
The four groups -- Greenpeace, WWF, Climate Action Network Europe and Transport & Environment -- criticised a report from an EU advisory panel which recommended using nuclear and fossil fuels to generate hydrogen in the short and medium-term.
The 19-member panel, including representatives from Royal Dutch Shell, Renault and DaimlerChrysler, was set up by the Commission to produce the report presented at the Brussels conference.
But the Commission said the panel's recommendations did not necessarily reflect the Commission's own views.
EU Energy Commissioner Loyola de Palacio and U.S. Energy Secretary Abraham both said renewable energy was at the heart of their policies.
"We recognize that the challenge posed by the carbon-based fuels must be addressed," Abraham told reporters.
"We intend that all our hydrogen will eventually be produced using emission-free technology," he said.
He said the U.S. hydrogen program would produce almost half its hydrogen from renewable sources.