The race is on to cultivate a seaweed that slashes methane emissions from cows

SAN DIEGO – Those concerned with climate change may soon feel less compunction about biting into a cheeseburger.

Researchers have recently discovered that feeding cattle and other livestock a specific type of seaweed — known as Asparagopsis taxiformis — can dramatically reduce the massive amount of planet-warming methane such farm animals pass into the atmosphere through burps and flatulence.

Scientists from San Diego to Vietnam to Australia are now working overtime to figure out how to best cultivate the underwater plant — which a growing number of private aquaculture companies are seeing as a potential cash cow.

Whether motivated by profits or global warming, the race is on to patent recipes for growing the seaweed and then figuring out how to ramp up production. Global demand is expected to far outstrip the capacity to harvest the subtropical seaweed from the wild.

In California alone there are 1.8 million dairy cows, with farmers of the greenhouse-gas-spewing animals facing a state mandate to slash their methane emissions 40% by 2030. Experts also expect that agricultural businesses may adopt the practice regardless of government pressure in order to market themselves as more environmentally friendly.

"Every time I talk about it, I get goose bumps," said Jennifer Smith, a marine biologist at UC San Diego's Scripps Institution of Oceanography, who said she can envision the university spinning off a startup to help meet local demand for the seaweed. But first, she has to dial in the recipe.

For several months, Smith has been experimenting in her lab with cultivating the seaweed to, among other things, maximize concentrations of bromoform — the compound that blocks the production of methane in cows, sheep, goats and other ruminant animals.

"By just manipulating nitrogen and phosphorus, we have already seen that we can double the concentrations of bromoform in just a week," she added.

The red-colored sporophyte is one of several phases of Asparagopsis. The subtropical seaweed also has a more fleshy stage with long stalks and branches.

Experts are debating in which stage to grow the seaweed. The practical considerations include not only the cost of cultivation but its carbon footprint. If growing the seaweed and shipping it to farms generates considerable amounts of greenhouse gas, the process could cancel out the benefits of reducing methane.

Some businesses are focusing on growing the more fleshy form of the plant in the ocean.

"Some people are saying let's grow the sporophyte," Josh Goldman said from Southeast Asia. "That's not that hard to do, but the problem is it's going to be expensive. Our vision of this is the most scalable and lowest cost way is in the ocean, rather than in tanks or pods on land."

Now it wants to cultivate Asparagopsis using nets of "seeded rope" that float several feet below the ocean surface. Goldman said the company hopes to have the process fully developed and in the patenting process by the end of the year. Then the company will not only start industrial-scale cultivation, but potentially sell the nets to other aquaculture businesses.

However, scientists have said more research is needed before the seaweed can be widely used on farms.

"We're in week seven of a six-month trial," said Ermias Kebreab, an animal science professor at UC Davis.

Specifically, Kebreab said his research is focused on determining whether the seaweed will have any harmful effects on the animals and if it will change the taste of milk or meat. There's also been some concern that the cows wouldn't like the flavor of the seaweed, but so far a little bit of molasses seems to do the trick.