Creating fuel from sunlight

By Casey Frye, CCNN Writer

The machine will concentrate light to thousands of degrees Fahrenheit! Wow that’s hot.

Even though many automobile makers have begun producing electric vehicles (EVs), millions of gallons of gasoline are used everyday. The problem is that fossil fuels – like gasoline – are limited, and we’re running out of supplies fast. If only there was a way to tap into the Sun for fuel. After all, it is the source of all life on Earth, so why couldn’t the Sun be a source of “life” for a car? Well, with a new device from the University of Delaware, it’s absolutely possible.

The researchers who invented the device call it – take a breath and bear with me now – the Gravity-Fed Solar-Thermochemical Receiver/Reactor (GRAFSTRR). Wow, I think I bit my tongue trying to read that quickly! The GRAFSTRR is a steel cylinder about two and a half feet tall and three feet wide. Though it has a small body, the reactor weighs about 1,000 pounds! It’s specially designed to take energy from sunlight and make solar fuel, however, the process is a little more complicated than trapping light in a bottle.

In the lab, University of Delaware researchers use 10 powerful lamps to mimic sunlight. The light passes through a special round window on top of the GRAFSTRR  that keeps air out, which can interfere with the fuel-making process. As the rays travel into the cylinder, a bunch of mirrors concentrate light up to 3000 degrees Fahrenheit! Inside the machine is a powder mixture of zinc oxide – the active ingredient in most sunscreens. It sounds like a super scientific name, but it’s really just a fancy way to say the elements zinc and oxygen are attached together. When the sizzling hot light hits the mixture, the zinc is able to separate from the oxygen and be used as a solar fuel!

Eric Zoepf, a mechanical engineer who worked on GRAFSTRR, explains, “Theoretically, we could capture about 40 percent of the energy, but in lab experiments to demonstrate the design, we get less than 3 percent.” Less than 3 percent? Wow, looks like the researchers have a lot of work to do. How long will it take to improve the reactor? “Our reactor is mostly a proof-of-concept, but I think it could be scaled up in my kids’ lifetime,” he noted. By that time, the research team plans to add an extra step where zinc reacts with water to make hydrogen fuel, the lightest and simplest fuel available!

Image of heat machine courtesy of University of Delaware and ASME.