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An idea has hit the news on Friday to produce petrol from air and water - removing CO2 from the atmosphere, combining it with hydrogen split from water vapour and turning it into a fuel that can go straight back into the petrol tank.
It's like combustion in reverse, and in essence it is what powers plants: CO2 and water in, energy-rich sugar molecules out.
But in matters of energy, nothing comes for free.
Just as plants need sunlight to pull off the trick, Air Fuel Synthesis, the firm profiled in the UK's Independent newspaper, need to use good old-fashioned electric energy to pull off theirs.
As with any novel fuel production or energy storage method, it is the numbers that matter: efficiency is king.
The degree to which this technique can fulfil its promise to lower CO2 and provide a sustainable fuel source depends crucially on the balance of energy it requires and the energy it stores.
First things first - squashing CO2 back into a molecule packed with energy is not a new idea.
For example, work done at Princeton University in the US and published in 1994 to make the fuel additive methanol from CO2 has more recently been refined and spun into a company called Liquid Light that is aiming to do the same thing.
In Iceland, Carbon Recycling International opened a plant at the end of 2011 drawing waste CO2 from a power station, with capacity to produce five million litres of methanol per year.
Air Fuel Synthesis build on these methods by turning the methanol into something more like petrol, using processes well entrenched already in the petroleum industry.
The firm, so far, has made five litres of their fuel in a two-year demonstration experiment in which they have invested £1m.
Peter Harrison, the firm's chief executive, told BBC News that the demonstration did not focus on efficiency, but rather a proof of principle.
"All we're trying to demonstrate is that here in the UK we can make petrol from air," he said.
"[These processes] are all capable of working at industrial scale, and we've brought it down to container scale. There' a lot of work to do to develop the supply chains and to reduce the costs.
"We've got a design now for a one-tonne-a-day unit, and we expect to be in production by 2015."
The recent resurgence in oil and gas production, and efforts to make the transport sector more efficient, are radically reshaping the nation's energy market, reported Paris-based IEA in its World Energy Outlook. North America would become a net exporter of oil around 2030, the global organization said Monday. "The United States, which currently imports around 20% of its total energy needs, becomes all but self sufficient in net terms -- a dramatic reversal of the trend seen in most other energy importing countries," the IEA stated.
The U.S. is experiencing an oil boom, in large part thanks to high world prices and new technologies, including hydraulic fracking, that have made the extraction of oil and gas from shale rock commercially viable. From 2008 to 2011, U.S. crude oil production jumped 14%, according to the U.S. Energy Information Administration. Natural gas production is up by about 10% over the same period.
According to the IEA, U.S. natural gas prices will rise to $5.5 per million British thermal units (MBtu) in 2020, from around $3.5 per MBtu this year, driven by rising domestic demand rather than a forecast increase in exports to Asia and other markets. "In our projections, 93% of the natural gas produced in the United States remains available to meet domestic demand," it said. "Exports on the scale that we project would not play a large role in domestic price setting."
North America's new role in the world energy markets will accelerate a change in the direction of international oil trade toward Asia, and underscore the importance of securing supply routes from the Middle East to China and India.
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