A kelp forest off Mexico’s Pacific coast. A project presented this week at an energy research conference
proposes using tiny robots to farm seaweed for use in biofuels.CreditReinhard Dirscherl/ullstein bild, via Getty ImagesBrad Plumer reports for The New York Times:

Off the coast of California, the idea is that someday tiny robot submarines will drag kelp deep into the ocean at night, to soak up nutrients, then bring the plants back to the surface during the day, to bask in the sunlight.

The goal of this offbeat project? To see if it’s possible to farm vast quantities of seaweed in the open ocean for a new type of carbon-neutral biofuel that might one day power trucks and airplanes. Unlike the corn- and soy-based biofuels used today, kelp-based fuels would not require valuable cropland.

Of course, there are still some kinks to work out. “We first need to show that the kelp doesn’t die when we take it up and down,” said Cindy Wilcox, a co-founder of Marine BioEnergy Inc., which is doing early testing this summer.

Ms. Wilcox’s venture is one of hundreds of long shots being funded by the federal government’s Advanced Research Projects Agency-Energy.Created a decade ago, ARPA-E now spends $300 million a year nurturing untested technologies that have the potential — however remote — of solving some of the world’s biggest energy problems, including climate change.

This week at a convention center near Washington, thousands of inventors and entrepreneurs gathered at the annual ARPA-E conference to discuss the obstacles to a cleaner energy future. Researchers funded by the agency also showed off their ideas, which ranged from the merely creative (a system to recycle waste heat in Navy ships) to the utterly wild (concepts for small fusion reactors).