An automaker takes a creative approach to renewable energy

Audi’s A3 Sport­back TCNG is being billed as the next big thing in sus­tain­able mobil­ity. The car runs on what Audi is call­ing “e-gas,” a sub­stance that is more or less equiv­a­lent to nat­ural gas and is cre­ated in a com­pli­cated chem­i­cal process explained here. Between its e-gas capac­ity and backup use of reg­u­lar old gaso­line, the A3 Sport­back TCNG has a trav­el­ing range of almost 800 miles.

Per­haps most sig­nif­i­cantly, Audi’s e-gas tech­nol­ogy can serve as a stor­age sys­tem for excess energy gen­er­ated from renew­able sources. One of the biggest prob­lems with solar energy and wind energy is that these meth­ods of cap­tur­ing power fluc­tu­ate over the course of a day and a year. Solar power peaks when sun­light peaks (mean­ing both mid­day and sum­mer­time), and wind power peaks on windier days and windier sea­sons. Of course, energy use also peaks. Peo­ple use more energy imme­di­ately after com­ing home from work, for exam­ple, when they are turn­ing on all of their house­hold appli­ances, than they do in the mid­dle of the night, when many of these appli­ances are turned off.

How­ever, the peaks of energy pro­duc­tion and energy usage rarely over­lap. When sun­light peaks in the mid­dle of the day, most peo­ple are too busy work­ing (albeit, often on lap­tops and smart­phones) to turn on their dish­wash­ers, tele­vi­sions, and lights at home. This dis­par­ity in peak times wouldn’t be much of a prob­lem, except that the elec­tric­ity gen­er­ated from these renew­able sources is often dif­fi­cult to store in the short term, and nearly impos­si­ble to store in the long term. The result is that much of the hard work that our solar pan­els and wind­mills do to gen­er­ate power goes to waste as the elec­tric­ity goes unused and van­ishes, hav­ing been cap­tured only briefly.

As described in their press release:

…[Audi begins] with wind, water and car­bon diox­ide sourced from a bio­gas plant. The end prod­ucts are renew­ably gen­er­ated eco-electricity…hydrogen …and syn­thetic methane (Audi e-gas) which can power vehi­cles like the new A3 Sport­back TCNG that will launch in 2013.”

Prob­a­bly the com­pelling ques­tions in this process are: how many watts of power are required to pro­duce a gal­lon equiv­a­lent of syn­thetic methane? And, is this method of stor­ing sur­plus elec­tric­ity more or less effi­cient than other meth­ods, like batteries?

The impli­ca­tions could be big. Audi’s facil­ity, and sim­i­lar facil­i­ties like it, could store the excess elec­tric­ity pro­duced by renew­able sources, sav­ing it from going to waste by con­vert­ing it to e-gas.

(In the Audi process, the CO2 comes from a point source, at a pow­er­plant; in the­ory, a sys­tem like this could also make use of CO2 cap­tured from the air, as in Klaus Lackner’s model.)

E-gas would then enter the nat­ural gas net­work, where it could be used, stored, or later con­verted back into elec­tric­ity. This process could rev­o­lu­tion­ize renew­able energy, mak­ing these green sources more effi­cient and thus more appeal­ing to com­pa­nies and con­sumers. Thus, whether or not the A3 Sport­back TCNG is suc­cess­ful from Audi’s per­spec­tive, the e-gas tech­nol­ogy that is being devel­oped to power it will cer­tainly go down as a major con­tri­bu­tion to a greener future.

Audi’s Werlte facil­ity will be com­pleted and opened for oper­a­tions in 2013, and the A3 Sport­back TCNG will launch the same year.