Obama and Romney are making bold claims about their energy credibility, but Big Oil is on a roll.

Four years ago, President Barack Obama assumed office on a tide of environmental optimism, promising to kick-start a United States energy transition from fossil fuels to clean energy, and to tackle climate change by cutting carbon emissions.

What a difference a recession, an intensely partisan political climate and a tight election campaign make.

In last week's presidential debate, Obama and Mitt Romney each insisted they were the best advocates of oil, gas and coal exploitation.

"We've opened up public lands, we're actually drilling more on public lands than the previous president, and he was an oil man," crowed Obama, countering Romney's assertion the White House had rolled back oil and gas drilling on public lands.


Obama lauded his administration's efforts to promote "clean coal". And as for off-shore drilling, it is on Obama's watch that Big Oil has had its best shot yet at exploiting the Arctic.

"It was disappointing to see Obama and Romney trip over one another in the debates on who loves coal more," says Janet Redman, co-director of the Sustainable Energy and Economy Network at the Institute of Policy Studies.

"That's the dirtiest energy in the US. It's not clean at the point of extraction, at the point of production, or at the point of consumption."

Obama has walked a fine line on the Keystone XL Pipeline, designed to carry Canadian crude oil from Alberta to Texas.

Part of the pipeline is operational, allowing Obama to boast about job creation, even as he kicked the entire project into touch until mid-next year in a bid to placate environmentalists.

Romney promises he will approve the pipeline on Day One. He wants to increase US fossil fuel and nuclear output, promote oil drilling off the East Coast, and rein in efforts by the Environmental Protection Agency to cut fossil fuel pollution.

"Romney's digging into the paradigm of American exceptionalism," says Redman. "That the way to be exceptional is to grow the economy using cheap fuel. Part of the problem is that he doesn't accept the science on climate change. Instead, he's trying to make climate change science look like doomsday thinking."

Both candidates want US energy independence. But whereas Romney pushes fossil fuels - and would lift the annual US$4 billion ($4.86 billion) tax break to Big Oil by US$2.3 billion, Obama is pragmatic, acknowledging transitions take time, as he promotes fossil fuels and clean energy.

Energy is the bedrock for much US policy, from building the economy to projecting military power. Yet neither candidate stresses conservation, even as consumption rises exponentially. According to the International Energy Agency, worldwide demand for electricity will double by 2030.

At the same time climate change makes it imperative carbon emissions are reduced. Renewables will help, but a big part of "energy independence" is shifting the conversation from boosting supply to curbing consumption.

Obama has set a new "corporate average fuel economy" (CAFE) baseline - 54.5 miles a gallon (23.17km a litre) for 2017-2025 cars - and carbon dioxide limits on new power plants.

And he insists he will double 2008 renewable energy output by the end of this year. At G20 talks, he advocates the shift from fossil fuel subsidies to clean-energy incentives. The White House has earmarked US$90 billion in cash and tax breaks for a "clean energy economy", with electric cars, solar and wind power, fast trains, energy-efficient homes and carbon dioxide sequestration.

A second Obama Administration is expected to take a tougher environmental and energy line, while Romney is expected to dump new CAFE rules, cut funding to the Commodity Futures Trading Commission, which monitors Wall Street oil trades, and dump Dodd-Frank fiscal reform, allowing speculators to inflate oil prices.

Meanwhile, Big Oil is on a roll, growing some 1.7 million US jobs.

"Oil supply capacity is growing worldwide at such an unprecedented level that it might outpace consumption," Leonardo Maugeri writes in Oil: The Next Revolution, published by Harvard University in June. "This could lead to a glut of overproduction and a steep dip in oil prices."

Much of this new supply will come from unconventional oil and natural gas, such as Canadian tar sands or US shale oils.

"The most surprising factor of the global picture, however," Maugeri writes, "is the explosion of the US oil output."

This is already evident. Horizontal drilling and hydraulic fracturing (fracking), have enabled the US to exploit huge and virtually untouched shale and tight oil fields.

Nationwide, 1839 rigs are searching for oil and gas, far fewer than the 4530 listed in 1981, but up on the 488 employed in 1999.

But there is growing concern about the effect of fracking on the environment and health.

An Earthworks Oil and Gas Accountability report, using a Pennsylvania survey, said "many residents have developed health symptoms that they did not have before - indicating the strong possibility that they are occurring because of gas development."

Last week, environmentalists filed suit against fracking in California, where 600 wells were fracked last year, releasing large amounts of methane, a greenhouse gas.

Though the boom suggests "Peak Oil" - supplies will crest, then plummet - is overstated, it does not factor in the wider cost of climate change.

In this context the best indicator on energy's direction may be those hard-nosed realists, the re-insurance companies, as they seek to recoup future loses from extreme weather events by investing in renewable energy.