Bush called for the US to reduce its gasoline usage by 20% over the next decade.

“When we do that, we will have cut our total imports by the equivalent of three-quarters of all the oil we now import from the Middle East,” he said.

“It is in our vital interest to diversify America’s energy supply – and the way forward is through technology.”

Bush called on Congress to introduce a mandatory fuels target of 35 billion gallons (132.5 billion litres) of renewable and alternative fuels by 2017, which he said was nearly five times the current target.

He also called on the major reform and modernisation of fuel economy standards for cars to save up to 8.5 billion more gallons of gasoline by 2017.

Bush said achieving these goals would dramatically reduce the nation’s dependence on foreign oil, but would not eliminate it.

“And so as we continue to diversify our fuel supply, we must step up domestic oil production in environmentally sensitive ways,” he said. “And to further protect America against severe disruptions to our oil supply, I ask Congress to double the current capacity of the Strategic Petroleum Reserve.”

“America is on the verge of technological breakthroughs that will enable us to live our lives less dependent on oil. And these technologies will help us be better stewards of the environment, and they will help us to confront the serious challenge of global climate change.”

But it is questionable just how meaningful this speech is. It comes at the lowest point of his presidency – Iraq is in chaos, polls show two thirds of the public are against him, and the Democrats control Congress.

The value of his policies is also in question. Bush is calling for a combination of alternative fuel mandates and increased fuel-economy standards.

“Let us build on the work we’ve done and reduce gasoline usage in the United States by 20% in the next 10 years,” he said.

But one must ask exactly what work has the US done in this area?

With similar policies in place since 1974, US petroleum consumption has increased by more than 20%. Every president since Richard Nixon has pledged to cut US dependence on foreign oil but legislators baulk at actually implementing potentially unpopular policies.

Expanding the US of ethanol and biodiesel is popular in America’s farmbelt states but the use of food crops for transport fuel is environmentally and economically questionable.

Greenpeace USA research director Kurt Davies told the BBC that he had serious doubts about whether ethanol is the ideal solution to America’s energy crisis.

“All the fossil fuels that are used in the production of corn, in the fertilisers and in the fuel, in the ploughs and transportation and so on and in the distillation process, it becomes almost a very dirty fuel,” he said.

To make biofuels truly environmentally sustainable, high-yield crops that will grow on marginal agricultural land must be developed.

Bush said he said he envisaged biofuels being produced from “everything from wood chips, to grasses, to agricultural wastes”.

The US native plant switchgrass is often touted as a potential energy saviour, but a lot of research and development will need to be undertaken to make this high-cellulose plant a viable source of transport fuel.

The president’s upcoming proposed budget for the 2007-08 will include $US179 million ($A229 million) for such biofuels and $2 billion in loan guarantees for cellulosic ethanol plants, the White House said.

Bush has also called for the first major changes to US vehicle fuel economy standards in decades but the cuts are relatively modest, at an annual average of 4% for new cars from 2010.

A lobby group for better fuel economy standards, Bluewater Network, dismissed the proposal as being a “gift” to the motor industry. “If the president were serious he would call for a doubling of the nation’s fuel economy standards,” it said.

The automobile industry has responded that it is already addressing environmental concerns and does not need new legislation to reduce fuel consumption.

The US green charity, National Environmental Trust, notes that energy and the environment have featured in every State of the Union address Bush has made but they say his policies have never matched his stated goals.