The just-concluded annual meeting of ARPA-E, an agency founded to nurture interesting energy ideas that may or may not work, featured an exhibition hall with scores of displays staffed by hopeful entrepreneurs.
Many of them seemed to be Ph.D. engineers; in some cases, you needed a Ph.D. yourself to understand what was being presented. But here are three simpler ones that seemed enticing, even if their practicality has yet to be demonstrated.
Some bacteria and algae turn sunlight into oils that can be burned in a car engine or used as raw material at a refinery in place of crude oil. Yet production of reasonable quantities at a reasonable cost has so far been elusive. Tobacco, meanwhile, is easy to grow but has no healthy use. Can the two be merged?
The research consortium Folium (from the Latin word for leaf), which includes the Lawrence Berkeley National Laboratory, the University of California at Berkeley and the University of Kentucky, has taken genes from those types of bacteria and algae and inserted them into tobacco plants. In the first year of work, it produced a crop and then used organic solvents to extract the oils out of the leaves. (Check out the video above.)
Further work on the project, which received $4.8 million from ARPA-E, will determine whether the oils can be used directly as fuel or must go to a refinery. But the tobacco is already yielding one product that could substitute for diesel oil, said Peggy G. Lemaux, a researcher at Berkeley.
Making these oils from tobacco, as opposed to some other crops, would not interfere with food production, Dr. Lemaux noted. And tobacco is already in surplus because of the decline of the cigarette market, so a large infrastructure is already in place, she said.
Researchers have modified the plants so that they have less chlorophyll, the chemical that converts sunlight into stored energy. Normally, chlorophyll is helpful in photosynthesis and makes leaves dark enough that the area beneath them is in shadow, killing off competing species. But “that doesn’t make sense in a monoculture,’’ Dr. Lemaux said, so the chlorophyll is reduced. With less chlorophyll, light not absorbed by the top layer of leaves can penetrate down to lower levels.
Among the challenges, however, is raising the amount of oil produced per pound of tobacco.
In another project, Proton Energy Systems received $4.6 million to work on using electric current to break up water molecules into hydrogen and oxygen.
One of the problems with integrating renewable energy into the electric system is that wind and sun are intermittent, creating challenges for grid operators who need to provide a constant supply of electricity. Proton came up with a product that is the direct opposite of a fuel cell, which converts hydrogen to electric current and water. The oxygen and hydrogen atoms are instead split up in a chemical reaction, and the hydrogen can either be turned back into electricity in a fuel cell or used for industrial purposes.
Proton is currently is working with the town of Hilo in Hawaii on an installation that would make hydrogen for a bus powered by a fuel cell. But the Proton equipment would also be connected to the local grid: upon receiving a signal, it would pull more current from the grid, or less, to keep supply and demand exactly balanced.
The system could store energy produced by the wind and sun when the electricity wasn’t needed, and balance the system on a moment-to-moment basis.
At another booth, a company called Otherlab was showing off a concept for a different kind of vehicle tank to hold natural gas. Today’s tanks for compressed gases are almost always spheres or cylinders, a geometry that affords maximum space. But it can be hard to find space for a cylinder or a sphere on a car, where every inch of space is usually spoken for by some mechanical system.
So Otherlab, which received $250,000 from ARPA-E, proposes a“conformable tank,” meaning a coiled pipe that would store gas in a flat area. The company had an eye-catching display of a coiled tube storing an example of a large volume of material: the human gastrointestinal tract.