Scientists should start thinking about what they’ll be able to do with renewable electricity in the near future when its cost falls to 1.5 cents per kilowatt-hour—and that future might include hydrogen less expensive than the equivalent produced from natural gas, former U.S. energy secretary Steven Chu said earlier this week.

“The cost of renewable energy at the best sites is 2¢ per kilowatt hour. And that is going to widen,” said Chu, now serving as president of the American Association for the Advancement of Science. “I’m an advisor to Royal Dutch Shell. They think within a couple decades the very best sites will go to 1.5¢ per kilowatt hour.”

Which makes cheap renewable electricity “a good way to position yourself as a graduate student and a post-doc and a researcher,” he added. “What research do I want to do, anticipating this will happen? Don’t wait for it to happen.”

Even at 4¢/kWh, Chu said electricity can compete with natural gas to produce hydrogen as a fuel or an energy storage medium. “But hydrogen produced from natural gas has a big carbon footprint—8.62 tons of carbon dioxide for each ton of produced hydrogen,” Forbes notes, citing the U.S. National Renewable Energy Laboratory. “Hydrogen from electrolysis can be much cleaner, if the electricity is from renewables.”

Chu added that scientists are close to solving some of the obstacles facing that line of thought, like the tendency of bubbles formed in hydrogen during the electrolysis process to interfere with the process itself.

“It may be that we’ll move to a partial hydrogen economy based on renewable energy,” Chu said. “These are some of the things I think people should think about, because we’re already in a fundamental energy transition.”