On Chevron's website there is a green mission statement.
Alongside a video featuring some earnest-looking members of the public and Chevron employees talking about the importance of renewables, the statement says this: "It's time oil companies get behind the development of renewable energies."
Elsewhere on the same page the company boasts that its own investment in geothermal, biofuels and solar is to the tune of millions of dollars.
Chevron is not the only oil company making a big deal about its green portfolio. BP has been using the tagline "Beyond Petroleum" for years now.
Nor does a quick review of the numbers quite undermine both companies claims.
According to figures released recently by the American Petroleum Institute (API), a trade group, Big Oil is the biggest investor in the race to create green fuels.
The API says that in the last decade the industry has put $71 billion into zero- and low-emission and renewable energy technologies. In contrast, the U.S. government has spent about $43 billion on similar efforts over the same period.
BP, for example, spent $1.6 billion last year to construct wind farms in Pennsylvania and Kansas, joining the 11 wind power plants it has already constructed. Chevron, meanwhile, recently opened a 29-megawatt thermal solar-to-steam facility at one of its oldest oil fields in California's San Joaquin Valley, which will increase crude oil production at the site.
However, everything is relative, and delve beneath the surface and it becomes clear that Big Oil's relationship to renewables is far more complex than the bold taglines and mission statements might imply.
For a start, most of the $71 billion figure touted by the API went toward making oil companies' existing fossil-fuel business more environmentally friendly. Only $9 billion went toward renewable energy investment. And even if all that money had been sunk into renewable technology it would still only be a drop in the ocean compared to what Big Oil spends on its core business.
To take the example of BP again: the $1.6 billion it spent on wind projects needs to be balanced against the $14 billion the company intends to spend on oil and gas exploration in the North Sea — only one of its many projects around the globe.
Between 2004 and 2009 Shell spent $1.7 billion on alternative projects. That amount is dwarfed by the $87 billion it spent over the same period on its oil and gas projects around the world.
When you consider that the top 15 oil and gas companies have a market capitalization of $1.9 trillion it's clear that the $71 billion over 10 years which we started with begins to look less and less impressive.
Of course, Big Oil would argue with some justification that this also is a reflection of market realities. The vast majority of the world's energy needs are still supplied by fossil fuels and in spite of the incredible leaps and bounds made by cleantech in the last two decades renewables remain a niche industry and, some would argue, unproven as a major power source for the future.
This view was best summed up by Rex W. Tillerson, the CEO of Exxon Mobil, who noted following the election of Barack Obama in 2008 that nothing had really changed.
"We don't oppose alternative energy sources and the development of those," Tillerson said at the time. "But to hang the future of the country's energy on those alternatives alone belies reality of their size and scale."
In truth, most of the impetus for clean energy development has come from other sources than Big Oil, which has rarely strayed much from the concerns of the balance sheet.
For example, the large-scale push into biofuels by most of the major oil companies in recent years must be seen in the light of the Energy Independence and Security Act, which President Bush signed into law in 2007 and which requires the country to work toward the production of 36 billion gallons of renewable fuels by 2022. As well in the context of Obama's green energy push and commitments made by the U.S. military to get half of its power from clean energy sources by 2020.
"All of our alternative energy businesses are businesses," Katrina Landis, the CEO of BP's alternative energy division, told Forbes recently. "We have to compete for investment dollars with all the hydrocarbon resources within BP."
In fact, oil companies have not just remained passive observers to the renewables revolution, waiting to jump on the bandwagon when there's money to be made. At times they have actively tried to undermine efforts to deploy more cleantech.
For example, Chevron's claims to be behind renewables are rather undermined by the fact that the company and its subsidiaries spent $2.1 million in lobbying the California state legislature last year over new laws requiring utilities to get a third of their power from alternative energy sources by the end of the decade.
Despite this, within the oil industry there seems to be a growing understanding that renewables will play a significant role in the world's future energy needs. Oil supplies are dying out and unless they want to die out with them, oil companies must diversify their portfolio.
However, many oil executives remain skeptical that renewables can fill the energy gap and, at least for now, they may have a point.
The world consumes around 85 million barrels of oil a day. According to a university study, to produce the equivalent amount of ethanol would require six times all the arable land in the U.S. and 75 percent of the world's cultivated land.
"Many of these companies see the world is changing," Daniel Yergin, a historian of the industry, told the New York Times. "But the challenge for a very large company is to get critical scale. People tend to forget the scale of the energy business."