© ZSW, Ellen Klose

ZSW suc­ceeds in pro­duc­ing cli­mate-neu­tral eLNG from air CO2

The sphere gleams sil­ver in the mid­dle of a high-tech instal­la­tion con­sist­ing of many hoses, com­pres­sors, switch­es and but­tons. It reminds a lit­tle of a for­tune teller’s crys­tal ball. And the future is what this is all about. The plant, which was devel­oped by the Cen­tre for Solar Ener­gy and Hydro­gen Research Baden-Würt­tem­berg, is intend­ed to achieve cli­mate neu­tral­i­ty more quick­ly. The sys­tem demon­stra­tor at the ZSW in Stuttgart gen­er­ates syn­thet­ic liq­uid methane from hydro­gen and air — so-called eLNG — using elec­tric­i­ty from renew­able ener­gies. Unlike LNG (Liqui­fied Nat­ur­al Gas), which is based on fos­sil nat­ur­al gas, syn­thet­ic elec­tric­i­ty-based eLNG (elec­tri­fied LNG) is pro­duced in a cli­mate-neu­tral way. This is because the liq­uid gas is pro­duced from green hydro­gen and car­bon diox­ide from the ambi­ent air.

Research on the “eLNG from the air” project fund­ed by the Baden-Würt­tem­berg Min­istry of Eco­nom­ics began 1.5 years ago. Now the project has been suc­cess­ful­ly com­plet­ed with the demon­stra­tion of the entire process chain. The tech­nol­o­gy can now be trans­ferred to an indus­tri­al scale.

“The pro­duc­tion of CO2-neu­tral gas is an impor­tant build­ing block on the way to a cli­mate-neu­tral future. With this project, we want to sup­port our plant engi­neers and com­po­nent man­u­fac­tur­ers in Baden-Würt­tem­berg in using the tech­nol­o­gy to open up new export poten­tial and sales mar­kets,” said Min­is­ter of Eco­nom­ic Affairs Dr. Nicole Hoffmeister-Kraut.

Exist­ing tech­nol­o­gy mod­ules and infra­struc­tures at the ZSW were used for the project. These include a tech­nol­o­gy for extract­ing CO2 from the air and an elec­trol­y­sis process for pro­duc­ing green hydro­gen. What was still miss­ing was an inno­v­a­tive, com­bined method to effi­cient­ly pro­duce and liq­ue­fy the regen­er­a­tive methane gas. This process has now been devel­oped at the ZSW.

Liq­ue­fied methane has an ener­gy den­si­ty 600 times high­er than gaseous methane and thus allows, among oth­er things, the inter­con­ti­nen­tal trans­port of large amounts of ener­gy by ship. In this way, the already exist­ing infra­struc­tures for LNG can be trans­formed in the direc­tion of cli­mate neu­tral­i­ty. As a new, cli­mate-neu­tral fuel, eLNG can be used instead of diesel for ship­ping and heavy goods trans­port or as a heat­ing oil alter­na­tive in indus­try. The CO2 sup­ply from air fur­ther devel­oped in the project — as well as the scal­ing con­cepts of the over­all process — can also be trans­ferred to oth­er fuel syn­the­ses, for exam­ple for the pro­duc­tion of syn­thet­ic kerosene.

When liq­uid methane flowed into the sil­ver sphere for the first time in the ZSW pilot plant, the joy was great. “The amount of liq­uid methane was still small, but the proof of con­cept had been pro­vid­ed,” reports Dr. Marc-Simon Löf­fler, head of the ZSW’s Renew­able Ener­gy Sources and Process­es depart­ment. He and his col­leagues are par­tic­u­lar­ly proud of the fact that all the com­po­nents in the process chain — elec­trol­y­sis, CO2 scrub­ber, metha­na­tion and liq­ue­fac­tion — were devel­oped in-house. “The plant is 100 per­cent made by ZSW,” adds project man­ag­er Bernd Stürmer. After prov­ing that the demon­stra­tor works, the process steps were fur­ther opti­mized. In the mean­time, the yield of the lab­o­ra­to­ry plant has been increased to one kilo­gram per hour.

The ZSW sci­en­tists have already devel­oped scal­ing con­cepts with which the process can also be used on an indus­tri­al scale. With opti­mal process inte­gra­tion, an effi­cien­cy of up to 55 per­cent (based on the regen­er­a­tive elec­tric­i­ty used) is pos­si­ble with this technology.

After this research suc­cess, things are mov­ing for­ward. The next step is now to win part­ners from indus­try for the com­mer­cial­iza­tion of the tech­nol­o­gy mod­ules. To this end, the ZSW’s Sys­tems Analy­sis depart­ment is inves­ti­gat­ing the val­ue cre­ation poten­tial for indus­try in Baden-Würt­tem­berg. “The plant con­cept opens up oppor­tu­ni­ties for com­pa­nies in var­i­ous indus­tries. In par­tic­u­lar, the tech­nol­o­gy for extract­ing CO2 from air is not only an impor­tant com­po­nent of the eLNG process chain, but also promis­es great devel­op­ment prospects in the glob­al mar­ket for cli­mate pro­tec­tion mea­sures,” sum­ma­rizes Maike Schmidt, Head of Sys­tems Analy­sis at ZSW. The project also aims to iden­ti­fy new export poten­tials and sales mar­kets for com­pa­nies. This will cre­ate the con­di­tions for Baden-Würt­tem­berg to take on a pio­neer­ing role as a tech­nol­o­gy provider for the pro­duc­tion of elec­tric­i­ty-based, regen­er­a­tive liq­uid methane.