A Cheaper Route to Making Chemicals from CO2

A startup called Liquid Light has developed an electrochemical process to use waste carbon dioxide as a starting ingredient for chemicals. The company says its method is significantly cheaper than conventional methods for converting CO₂ into chemicals.

The Monmouth, New Jersey-based company announced last week that it had built a prototype that can make ethylene glycol from carbon dioxide, electricity, and a source of hydrogen, such as water. Liquid Light estimates that producing one ton of the chemical would require $125 worth of carbon dioxide, compared to more than $600 for traditional feedstocks such as oil or natural gas. The company suggests that a chemical producer could get carbon dioxide using existing separation techniques on smokestack gases from a factory boiler or generator.

Liquid Light’s technology uses catalysts and electricity. In an initial step, a catalyst-covered electrode produces a two-carbon oxalate molecule from carbon dioxide molecules. Separate catalysts then drive reactions to form ethylene glycol, a widely used industrial chemical and a precursor to polyester fiber and plastic bottles.

The main advantage of Liquid Light’s process is its potentially lower feedstock costs. If electricity is provided by natural gas, nuclear, or renewable sources, Liquid Light’s process could also have lower carbon emissions than conventional methods, the company says.

Using catalysts to convert CO₂ into chemicals and fuels has become an active area of research, but it faces technical hurdles. For example, the reactions need to be done more quickly and efficiently than is currently possible (see “Company Makes CO₂ into Liquid Fuel, with Help from a Volcano”). Another barrier is economic, says Joel Rosenthal, an assistant professor at the University of Delaware who has studied catalytic conversion of carbon dioxide, because fueling the reactions requires large amounts of electricity.

Also, metal catalysts often produce multiple products from carbon dioxide. For example, the process can result in carbon monoxide and methane, and it’s expensive to separate them out. Liquid Light’s work is impressive, Rosenthal says, because it appears to be able to make a commercially valuable chemical without generating any unwanted extra products. “If they can make ethylene glycol from CO₂ selectively with competent kinetics and without using a ton of energy, that’s potentially a very big deal,” he says.

Liquid Light won’t disclose what catalyst it uses for CO₂ conversion, except to say that it’s low-cost, has been stable over time, and that the reaction requires relatively little electricity. Its prototype cell is made with two square metal plates about three feet wide and a few inches apart. To produce at large scale, several of these cells would be connected, much the way a fuel cell stack is designed. The company, which counts BP Ventures as an investor, intends to run trials with an industrial partner in the next two or three years.

Liquid Light’s electrochemical production method for chemicals would be an appealing substitute for current petroleum-based methods, particularly for chemicals with oxygen in them, says Gary Dirks, a former BP executive and a scientific advisor to Liquid Light. “You get products that are not easy to get from oil-based hydrocarbons in a much simpler process and at lower cost,” he says.

In the future, renewable sources of energy, such as solar and wind, could power the electrochemical conversion of carbon dioxide into chemicals and fuels, which means production of those products would be carbon neutral or carbon negative, says Thomas Jaramillo, a professor at Stanford University and a researcher on the electrocatalytic conversion of carbon dioxide into fuels. And, he points out, “electrochemical technologies are already used in a very large scale.”