Fuels from Sunlight

The Laws of Thermodynamics are harsh. They mandate that each time you transform energy from one form to another, you are going to lose at least a third of it. And that’s if your systems are perfectly efficient, which none of them are. Think about making biofuels using solar panels for the energy input.

The Laws mean that only two-thirds of the light energy hitting the panel is actually converted into electrical energy. (In reality it’s more like one-fifth, a pretty dismal capture rate.) Then that electrical energy gets converted to a different voltage and to AC rather than DC current. Finally it gets converted to heat energy to heat up the ingredients that will become biofuel. The result of this chain of conversions is that you need acres and acres of solar panels to run a biofuel plant, enough solar panels to make the plant uneconomical. That’s why it isn’t done despite a commonly held belief that doing so will yield carbon neutral gasoline for us to run our cars on. And that’s why this Department of Energy initiative is so important.

The DOE announced the creation of the “Fuels from Sunlight” Energy Innovation Hub. The idea is to develop ways of generating fuels directly from sunlight. The California Institute of Technology and the DOE's Lawrence Berkeley National Laboratory will operate what they call the “Joint Center for Artificial Photosynthesis (JCAP).”

The goal of JCAP researchers is to simulate natural photosynthesis to directly produce liquid fuels. They are essentially taking sunlight, water, and carbon dioxide and making a clean fuel. It’s a little more complex than it sounds obviously. They have to find or develop a whole set of system components - light absorbers, catalysts, molecular linkers, and separation membranes – and then integrate them into an operational system. They’re also charged with figuring out the “scale-up” strategy that will enable the technology to be deployed on a commercial scale. Scaling up is one of the biggest obstacles faced by innovative technologies that tend to work in the lab, but crash and burn as soon as someone tries to do it on a scale that makes economic sense. The DOE intends for them to move from fundamental to applied research and technology development, setting the stage for a direct solar fuels industry.

This initiative is a game-changer. It would be as if the Sun got suddenly ten times brighter than it is and was showering ten times as much energy upon us. It’s a big bet, of course, with a long term payback. The DOE is funding JCAP to the tune of $122M for five years. But that’s what governments are for, to boldly go where no corporation dares risk its profits.

Stay tuned!

Paul Birkeland lives in Seattle, WA, US, and develops Strategic Energy Management Systems for government, commercial, and industrial organizations through Integrated Renewable Energy.

Photo: Professor G1