The nation's top scientists yesterday proposed the most ambitious research agenda yet to limit global warming by midcentury. It centers on "negative emissions technologies," or NETs.

These technologies would pull carbon dioxide from the atmosphere and either store it underground or, as described in the second of two new reports, combine it into useful products like concrete and paving materials.

Stephen Pacala, chairman of one of the committees within the National Academies of Sciences, Engineering and Medicine that worked on the project, said NETs would be a companion to other efforts aimed at lowering greenhouse gases. In his view, these technologies could enhance climate regulations on automobiles and power plants.

These NETS, which might include machines and as-yet expensive and poorly understood chemistries, could achieve "negative emissions" by removing CO 2 from the air.

"The net effect on the atmosphere is the same," Pacala explained yesterday at a press conference accompanying the release of his panel's report.

Yesterday's announcement follows the release of a major report earlier this month by the Intergovernmental Panel on Climate Change (IPCC). It suggested that a process like NETs might be needed if nations fail to limit the rise in global average temperatures to 1.5 degrees Celsius within a few decades.

The IPCC is concerned that global emissions might "overshoot" the intended limits and cause runaway climate reactions, such as unbearable levels of heat in some nations and rising sea levels in others. Pacala, a professor of ecology and evolutionary biology at Princeton University, said that NETs might be an effective way to meet the goals of the Paris climate agreement without imposing severe economic hardships.

His committee noted that it was "acutely aware" that President Trump had promised to pull the United States out of the Paris accord by 2020. However, it added that there could be "economic rewards" and global markets for "nations that develop the best technology."

The panel pointed out that Congress passed a measure in February that included bipartisan support for a tax credit in a budget compromise. It provided $50 per ton of carbon dioxide to any business that can capture and store the gas. Called the "Furthering Carbon Capture, Utilization, Technology, Underground Storage and Reduced Emissions Act," it was part of an agreement that was signed by Trump.

A cross-section of utilities, coal companies, environmental groups and labor organizations supported the measure.

Pacala noted that global markets for cost-effective technologies might eventually be worth as much as $500 million a year. He said carbon mitigation will become extremely difficult for some industries, such as airlines, because there are no cost-effective substitutes for jet fuel. Some non-carbon biofuels hold promise, he said.

"But that would require a lot of arable land," Pacala added, noting that population growth is expected to double the demand for food.

He said a series of public-private partnerships could encourage competition between startups and other companies that the Department of Energy could help finance and oversee. It could later select the most promising technologies for pilot projects that might increase the efficiency of removing carbon and reduce its costs to under $100 a ton.

At some point, the annual cost of research and development might reach as high as $900 million a year, "but that would not be every year," Pacala said. At the moment, the leader in negative emissions technology is a Swiss company called Climeworks. It announced a process last year to remove CO 2 from the atmosphere and send it to nearby greenhouses to help them grow vegetables. The production costs as much as $600 per ton, Pacala said.

The problem of scaling up NETs is compounded by the fact that carbon dioxide grabbed from the air is extremely diluted compared with the CO 2 in power plant emissions. There are also expected to be considerable energy costs to power fans that suck air into the machines, which then must collect and compress it.

One benchmark for success for the new multiyear federal research project suggested by the panels is that the United States spent more than $22 billion to develop solar and wind energy between 1978 and 2013. "These investments have paid off spectacularly," Pacala's panel reported.

Pacala said that extracting CO 2 directly from the air was one of two technologies favored by the panels because, once developed, they appeared to have no inherent limitations. The second technology among many mentioned in the panels' reports is called "carbon mineralization." It takes advantage of the fact that CO 2 "reacts spontaneously" with carbon-containing rocks.

CO 2 can be stored in some rock formations, and it eventually becomes part of the rocks. CO 2 can also be used in making certain long-lasting construction materials such as concrete and cement, products that are needed by huge markets in the United States and other nations.

Pacala noted that last week, a "sister committee" to his panel, which contained scientists and company executives, produced a report called "Gaseous Carbon Waste Streams Utilization." It lists a number of other marketable products that may, over time, evolve from more intense climate change-connected research.

The second pathway is to use renewable energy to convert CO 2 into chemicals and fuels. The technology for this is used in a few commercial products, primarily for urea, a chemical used in many plastics, and salicylic acid, which is used for common medical treatments for acne, dandruff and warts.

Using certain catalysts, CO 2 can also be made into methane and liquid fuels.

Some biological processes can also result in liquid fuels. In 2008, when crude oil prices topped $100 a barrel, DOE was making headway using algae to make a form of biodiesel oil, inspiring several startup firms to enter the business. They crashed in 2016 when crude slumped to $30 a barrel.

The first panel's report, according to the academies, was co-sponsored by DOE and other federal agencies. The second panel was co-sponsored by DOE and Royal Dutch Shell PLC, a major oil company that is supporting climate change-related research around the world.

One of Shell's projects, recently announced by DOE's National Renewable Energy Laboratory, aims to encourage startups focused on advanced battery chemistries for electric cars.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.