The Sorghum Solution?

Researchers at the Salk Institute in La Jolla are taking a different approach to carbon capture and sequestration — by working to remove carbon from the atmosphere by developing better varieties of plants, such as sorghum.

Article By Rob Nikolewski

When energy nerds talk about carbon capture and sequestration, CCS for short, the discussion normally centers on finding ways to take carbon dioxide from fossil fuel power plants, transporting it to a storage site and depositing it so the CO2 does not enter the atmosphere.

But researchers at the Salk Institute in La Jolla take a different approach to CCS — by working to remove carbon from the atmosphere by developing better varieties of plants, such as sorghum.

The institute’s plant-based solution to help fight climate change — called the Harnessing Plants Initiative — received a $2 million donation from Sempra Energy this week. The San Diego-based Fortune 500 company will be the lead sponsor of a five-year project called “Sequestering Carbon Through Climate Adapted Sorghum.”

“It’s a highly productive crop that grows in very warm and hot drought environments,” said Salk professor Wolfgang Busch, co-director of the initiative. A gluten-free cereal grain often used for livestock feed, sorghum is “a crop that will be very much suited to grow in the changed environment that we expect to have in a decade or so … We are thrilled that we can work on a crop that can potentially grow in California and the local environment here.”

So how can plants reduce carbon? Think back to middle school science class: Plants have helped stabilized the climate for eons by capturing CO2 through photosynthesis and converting it into oxygen. Plants breathe in CO2 and store carbon in their biomass. Salk researchers look to develop plants that can keep more carbon in their root systems, which not only makes the crops more robust but will improve the quality of the soil.

“You think about a rich soil, which is kind of dark — that’s the carbon,” Busch said. “When the soil has the ability to hold on to nutrients better, that is important for plant productivity but also (helps) to hold on to more water, which is important for times when you have flooding … So we think of this as a win-win.”

Working on six crop species in the initiative, Salk researchers work to make the plants draw down excess carbon from the atmosphere while also providing more food, fuel and fiber for a global population estimated at about 7.7 billion.

The Salk initiative aims to develop crop plants that will be used in significant global acreages to store long-lasting carbon in the ground. The impact could be huge. Salk researchers estimate if 70 percent of the target crops are converted into carbon-sequestration-enhanced crop plants worldwide, between 1.5 to 6 gigatons of CO2 can be sequestered per year. That’s the equivalent of up to as much as one-third of human-caused CO2 emissions that accumulate in the atmosphere each year.

“This project has the potential to help remove significant amounts of carbon from entering our atmosphere and aligns with Sempra Energy’s portfolio to advance the global energy transition to lower-carbon energy sources,” Kevin Sagara, group president of Sempra Energy, said in a statement. Sagara also serves on the advisory committee of the Harnessing Plants Initiative.

Most of the attention on CCS has centered on isolating emissions at power plants and industrial facilities. For example, the Sleipner gasfield in the North Sea scrubs out the CO2 and then sends it by pipeline to a deep saline reservoir. The coal industry has made efforts to capture and sequester carbon but results have been spotty at best and some attempts, such as the Kemper plant in Mississippi, were plagued by technological and economic problems.

“When you think about technical carbon capture, it’s very difficult and highly energy intense,” Busch said. “Scaling is also a very hard problem. But by using agriculture, we’re using a distribution system that’s already established. We don’t need to reinvent the wheel. We just need to make sure that the plants that are grown are better at storing carbon in the soil.”

In addition to developing new strains of carbon-reducing plants that farmers can seed, Salk researchers are working on a program to restore and preserve wetlands around the world, which act as significant carbon sinks — places that absorb more carbon than they release.

“People realize pretty quickly, wow, that is something that sounds feasible — this is a natural process,” Busch said. “I think it’s often about reminding people what plants do and what they’re capable of.”


This story originally appeared in The San Diego Union-Tribune.