Solar Fuels: How Close, How Real?
by Jim Lane (Biofuels Digest) Could a liquid fuel technology emerge that connects solar PV to the efficiency of electric engines — but, this time with long driving range and near-instant refueling instead of laborious recharging?
And, could the liquid fuel be made from the very waste CO2 that bedevils our environment?
Those ideas just took a big step forward — involving some Princeton research and a company (focused itself on chemicals) called Liquid Light.
There’s a class of fuels that don’t use an intervening biomass to make a fuel — so, though they use biology or waste carbon, they’ve bristled at being called “biofuels”. Instead, the technologies that depend on unique pathways to converting CO2 and water to fuels and chemicals prefer “solar fuels”.
By any name, they’re fascinating. What’s the latest?
The most well-known of the solar fuels is, without a doubt, those from Joule Unlimited, which pioneered the term “solar fuels” in the first place and is the closest to reaching scale. Using modified cyanobacteria, they form jet fuel, diesel and ethanol under the brand name “Sunflow” — and have been operating a demonstration facility in Hobbs, New Mexico for going on two years now.
But other technologies have come along — not following the same biotechnology path, but utilizing some of the same underlying concepts of waste CO2 utilization, bypassing biomass, and making target fuels and chemicals directly from the same inputs that plants use to make biomass in the first place.
About Liquid Light One of the most interesting of these is Liquid Light, which emerged from stealth mode in the past year, and focuses on electrocatalytic conversion of CO2 to useful fuels and chemicals. The company’s first process is for the production of ethylene glycol (MEG), with a $27 billion annual market.
James Liao’s lab at UCLA has been working on some of the same ideas. Back in 2012, they reported that “We’ve been able to separate the light reaction from the dark reaction and instead of using biological photosynthesis, we are using solar panels to convert the sunlight to electrical energy, then to a chemical intermediate, and using that to power carbon dioxide fixation to produce the fuel. This method could be more efficient than the biological system.”
“Instead of using hydrogen, we use formic acid as the intermediary,” Liao told Gizmag, based on work he published in Science. “We use electricity to generate formic acid and then use the formic acid to power the CO2 fixation in bacteria in the dark to produce isobutanol and higher alcohols.”
More interestingly, there are opportunities here to — in the long term — connect two of the most hyper-efficient technologies around – solar PV and fuel cells. Is formic acid going to be the crucial intermediate that links high-efficiency energy capture to high-efficiency electric engines? READ MORE and MORE (Science Daily) and MORE (AlphaGalileo) and MORE (Power Engineering) Abstract Abstract