In recent years, the trend has been for Big Oil to back out of the renewable energy and cleantech business.

In September, Chevron Corp. finalized the sale of its renewable energy subsidiary OpTerra Energy Services. The oil giant also sold the energy efficiency and renewables arm of Chevron Energy Solutions, a division of Chevron USA, and pulled back funding for biofuel projects.

ExxonMobil Corp. has also dropped funding for biofuels projects. The British oil major BP divested its wind farm division in the United States last year to focus on its high-yield oil and gas projects. And Royal Dutch Shell came under fire from environmentalists in 2009 for selling off its wind and solar projects to focus on biofuels and carbon capture andstorage

For these century-old energy companies, the technologies of the future seem to be technologies that advance Arctic oil drilling and shale gas development rather than renewables. And why not? The core competencies of Chevron, Exxon and others lie in drilling, piping and shipping oil and gas. Even the most nimble of tech companies would hesitate before spending billions to enter an emerging industry where they don’t necessarily add value.

However, environmentalists and cleantech advocates argue that by abandoning renewables, oil companies are missing out on an enormous business opportunity. Convincing Big Oil to leave fossil fuels in the ground is also necessary to avoid the most catastrophic effects of climate change.

Shell, it seems, might be listening to those arguments. At a cleantech event in Boston last week, Shell Technology Ventures executive Henrik Holland alluded to a renewed strategic interest in renewables and a commitment to long-term financial support.

“We’re entering a space where many have left,” he said. “We can tolerate the high capex.”

At a time when venture capital investments in clean technology have slowed, the industry would undoubtedly welcome long-term backing from a large corporation like Shell. If projects are financed in the right way, Shell can “be there in twelve years' time, [and] when something goes wrong, we can be that partner on the other side of the table with some guarantees,” Holland added.

Last spring, Shell Technology Ventures announced its plans to invest “hundreds of millions” in emerging technologies through a second-round venture fund. Geert van de Wouw, director of Shell Technology Ventures, told Greentech Media that three-quarters of the money would be aimed at investments in technologies across its oil and gas operations, including geophysical imaging, well construction and automation, and water and fluid treatment. The remaining quarter, said van de Wouw, would be invested in “future energy” technologies, such as advanced biofuels and solar-assisted enhanced oil recovery.

Last week, Holland expanded on where Shell's interests lie today. He noted Shell’s investments in Brazil’s biofuels industry and the company’s involvement in several wind projects (a total of ten wind parks, including a 36-turbine offshore wind project). Holland said that Shell is also looking at “various themes” for new businesses that will reduce carbon emissions, including grid-scale energy storage, industrial and residential efficiency and hydrogen technologies.

“And we’re interested in understanding where solar is going to go,” he said. Shell has already invested in Japan-based CIGS solar cell maker Solar Frontier.

For Shell, investing in low-carbon technologies is all about playing the long game. “We have a heavy oil and gas view of the world. Projects we support will enable us, as an organization, to change,” Holland continued. “Solar is very different from oil and gas. Financing challenges are very different. In an organization that has done the same thing for 100 years, we want to learn in that space by actually doing things.”

Working with partners is how Shell can ensure it survives through the next century. Energy demand is expected to grow dramatically, more than doubling by 2050 according to Shell’s own forecasts. Meeting that demand will require developing a lot of new energy resources, but also acting responsibly, which is why Shell is building a portfolio of new projects that include a carbon cost of 40 euros per ton, said Holland.

Shell CEO Ben van Beurden underscored the urgency of mitigating carbon emissions in a recent speech at Columbia University. “The potentially devastating impact of climate change, if unchecked, is a concern for all of us,” he said.

He also backed growth in renewables and energy efficiency. The U.S. Energy Information Administration estimates that 15 percent of global energy will come from renewable energy sources like hydropower, biofuels, wind, geothermal and solar by 2040, up from 11 percent today. Beurden said Shell’s scenarios team believes that figure could be as high as 25 percent by 2050.

Energy demand in the coming decades will still need to be met by traditional sources like oil, gas and nuclear. But these recent comments from Shell executives could signal a strategic shift within the company that would see a greater emphasis on low-carbon technologies as part of a long-term move to diversify Shell’s business.

Greentech Media contacted Shell for comment on changes to its strategy, but had yet to receive a response by the time of this writing.

Environmentalists, at least, aren’t buying the "green" rhetoric.

“Actions speak louder than words. If Shell is serious about investing in a clean energy future they must stop actively undermining our climate and clean energy laws,” said Merrian Borgeson, senior scientist at the Natural Resources Defense Council (NRDC).

Yesterday, NRDC released a report highlighting lobbying expenditures and front groups propped up by the oil industry -- including Shell -- aimed at curbing California’s clean energy action. NRDC called on major oil companies to distance themselves from the Western States Petroleum Association, which it says is leading the attack on climate change legislation in California.

The Union of Concerned Scientists (UCS) also launched a campaign pressuring Shell to join tech firms including Microsoft, Google and Facebook in dropping support for the American Legislative Exchange Council, a group that has modeled legislation to oppose climate action and repeal incentives for renewable energy.

“It’s time that Shell makes good on its CEO’s words on climate science,” wrote UCS.