INL develops new petrochemical process involving less energy consumption, lower CO2 emissions

INL researchers Ting He (left) and Dong Ding have developed an electrochemical process for creating synthetic fuels and plastics that uses 65 percent less energy.

A team of Idaho National Laboratory researchers has pioneered a process they say could cut the energy consumption in petrochemical manufacturing by 65 percent and carbon dioxide emissions by as much as 98 percent.

Since the early 20th century, everything from gasoline and diesel fuel to plastics has been made by cracking complex hydrocarbon molecules found in oil, coal and natural gas with tremendous amounts of heat and pressure. In an article published last week in the scientific journal Energy and Environmental Science, the INL researchers report they’ve hit upon an electrochemical process for converting ethane in natural gas liquids to ethylene, which is used to make polymers for everything from cellphone cases to disposable diapers.

Ethane offers a simpler hydrocarbon to refine than oil. It can be converted to ethylene thermally, at temperatures of up to 850 Celsius, the same way as with oil. But the new process involves much lower temperatures, hence much less energy consumption, as it feeds ethane to the anode in an electrochemical membrane reactor. Electricity in the reactor separates protons (hydrogen ions) from the molecules, leaving ethylene. The protons themselves migrate through a dense electrolyte to the cathode, where they combine with electrons to form hydrogen gas.

INL's research is being conducted in conjunction with Massachusetts Institute of Technology and the University of Wyoming. The U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) announced in February that the project would receive funding as part of $35 million being awarded to early-stage innovative technologies for advanced manufacturing.

Several factors are driving the project, said INL researcher Dr. Dong Ding.  First, the shale gas revolution has provided a plentiful supply of natural gas at historically low prices. Second, the declining cost of electricity makes electrochemical refining more economically feasible.

Theoretically, if the process was to be powered by a renewable source and the captured hydrogen was incorporated into fuel cells, there could be a net gain in process energy, he said. From a CO2 standpoint, using a non-carbon source of electricity — nuclear, hydro, wind or solar — could cut the carbon footprint down to 2 percent of traditional production methods.

The INL team will focus next on how to convert methane into ethylene. Methane is also found in natural gas — more plentifully than ethane, in fact — but its carbon-hydrogen bond is harder to break, Ding said.

Peer reviewers for the Energy & Environmental Science article called the work "convincing," "timely," "original" and "highly interesting."