Greenhouse gases are wreaking havoc on the planet. What if they could be used for good?

When Gaurav Sant thinks about how the planet might dodge catastrophic climate change, at the front of his mind are not solar panels or wind turbines or electric cars.

It’s cement.

Sant spiritedly talks of how cement production is exhausting the Earth, accounting for an absurd share of the greenhouse gases that industry spews into the air. The director of a team of civil and environmental engineering innovators at UCLA, he poses an intriguing question:

What if all those cement-factory emissions blowing into the atmosphere were instead bottled up and transformed into a useful product?

More cement, in fact. But a kind that barely has a carbon footprint at all.

“We need transformative solutions” to global warming, Sant says. “And this approach is fairly simple to implement.”

What Sant is talking about is called carbon capture, and after years of being dismissed as an unrealistically costly sideshow, it is increasingly seen as essential to keeping global warming in check.

California stands at the center of innovative efforts to develop carbon-capture and removal technologies. State officials have begun working them into their climate action plans.

And this month, when Gov. Jerry Brown welcomes officials from around the world to a global climate conference in San Francisco, the question of how far world leaders should move toward embracing such ideas will be a major focus.

“If you want to take action and do it fast and do it big, this is the way to go,” said Julio Friedmann, a leader of the Department of Energy’s carbon management efforts during the Obama administration.

“Every reasonable scenario” that the United Nations Intergovernmental Panel on Climate Change has modeled for preventing warming from becoming intolerable relies in part on fledgling technologies that divert carbon from the atmosphere to massive underground aquifers or pour it into products as varied as cement blocks, stylish sneakers and kegs of beer.

Some techniques aim to capture carbon from the chimneys of power plants and industrial factories. Others, like the units designed by Carbon Engineering, a British Columbia firm in which Bill Gates is a major investor, involve giant vacuum-like machines sucking carbon out of the air.

Several of the technologies have seen their production costs plummet to a point that makes them economically feasible, thanks to the brisk pace of innovation and some new tax breaks passed by Congress this year.

Not everyone is sold on the ideas, however. Indeed, one of the main factors that makes carbon capture appealing to economists, engineers and entrepreneurs can make it deeply problematic to some environmental activists.

“This will make a dramatic difference” in preventing the planet from overheating, “but it does not affect the way you and I behave,” said Carbon Engineering CEO Steve Oldham.

“You can keep using the same car, keep driving your kids to hockey practice. But the carbon footprint for doing it is eliminated.”

For some environmental activists, that’s also a huge drawback. They hope that the fight against climate change will open the way to a fundamental restructuring of the global economy. Carbon capture would make some of that restructuring less urgent.

One of the most practical uses of carbon that is captured from the atmosphere, for example, is in oil extraction, through a process in which carbon dioxide is injected into underground oil reservoirs to push fuel to the surface.

Greenpeace points to this in warning that the carbon capture movement is “a costly, risky distraction” at a time the focus should be on rapidly replacing fossil fuels with solar, wind and geothermal energy.

Another problem is that carbon capture technologies have long been associated with the “clean coal” movement. Some of the biggest carbon-capture projects to date have involved retrofitting coal plants, prolonging the life of environmentally unfriendly coal energy. The results of such efforts have been mixed.

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But other climate groups are rushing to embrace carbon capture and removal, reasoning that the technology promises to accelerate development of climate-friendly fuels and products.

Oldham’s firm aims to suck carbon out of the air and put it to use producing clean-burning fuels for cars and jets. So far, it only has one pilot plant up and running. It plans to move into real-world production in the next few years.

Such carbon removal or “negative emissions” plants can only go so far in stemming warming. Carbon Engineering would need to build 60,000 of its plants to entirely offset global emissions.

Other entrepreneurs have pushed ahead with different techniques for reusing carbon extracted from the air.

The judges at the XPRIZE, a competition to develop breakthrough products that make use of carbon emissions, were impressed enough with Sant’s plans for cement to advance the UCLA team to the finals of their $20-million contest. To kick off the competition, a sponsor, NRG Energy, commissioned “the Shoe Without a Footprint,” a stylish sneaker made from recycled carbon emissions.

At a Department of Energy boot camp for entrepreneurs last year, one participant developed a process for capturing the hundreds of millions of pounds of carbon dioxide that escape during fermentation at beer factories and packaging it in capsules that can be used to carbonate the beverages.

Others are racing to line up venture capital to build pilot plants like the one Carbon Engineering runs, with the aim of showing that the technology is viable and cost-effective. The centrist advocacy group Third Way has published a map that identifies more than 300 carbon-capture and removal projects worldwide.

“The problem is not whether the technology exists to tackle carbon dioxide,” Sant said. “But we have to show we can do it in a way that is economically attractive.”

Congress gave that quest a boost this year when it approved new tax breaks for carbon-capture and carbon-removal projects. It was rare bipartisan action on climate change in Washington. Republicans, normally loath to subsidize such innovation, were attracted by the benefits it could provide to fossil-fuel companies.

It’s a Faustian bargain for the climate movement. Pipelines would be needed to ship all the carbon dioxide that environmentalists want to divert from the atmosphere, and the oil companies are motivated to build them.

“We need to stop using oil to meet our climate goals, so adding more of it seems counterproductive,” said Noah Deich, co-founder of the Oakland-based Center for Carbon Removal. “But this is a great transition strategy.”

Advocates at the Clean Air Task Force, a Boston-based group that promotes low-carbon technologies, argue that oil pumped from the ground using carbon captured at factories and power plants has a much smaller carbon footprint than conventionally extracted oil.

“This cuts the emissions associated with a barrel of oil by nearly two-thirds,” said John Thompson, director of markets and technology at the Task Force. “This is a deep, deep reduction.”

The lion’s share of carbon dioxide extracted from the nation’s power plants and industrial factories wouldn’t make its way into oil fields. Or into cement production or sneaker manufacturing, for that matter. There is just too much of it. Most of the captured emissions are destined to be pumped back into aquifers deep underground, where they can’t escape into the air.

That raises the bigger question of who is going to pay to pull all that carbon from the air and put it underground if they get nothing tangible in return.

That’s where policies like those California is developing right now come into play. Under the state’s climate action plan, companies are increasingly going to face mandates to help lower their net emissions. If they can’t get there on their own, another option may be to pay a firm to suck some carbon out of the air for them.

Friedmann argues that the Paris climate goals that almost every world leader other than President Trump is aiming to fulfill will push economies toward creative ways to embrace the technologies. He looks at it like a sewage or garbage bill: People pay them, because if they don’t their community falls apart.

“How much are people willing to pay to do this? Nobody knows,” Friedmann said. “But now you can do it,” he said, pointing to a plant that recently went online in Iceland that will suck greenhouse gases from the air and deposit them underground for a fee. “You couldn’t do this last year, and now you can. That is worthy of attention.”

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evan.halper@latimes.com | Twitter: @evanhalper