Nafion-based cells, Ashcraft said.
DyPol hopes to sell the membrane technology to companies building fuel cells for military applications such as portable radios and GPS devices. Lilliputian Systems, another MIT spinoff that’s developing methanol-based fuel cells for consumer devices such as cell phones, might also be a customer eventually, said Ashcraft.
Hydrogen from Wastewater Sludge
Chul Park, an assistant professor in the department of civil and environmental engineering at the University of Massachusetts, Amherst, gave a talk about a new way to treat municipal wastewater that could reduce the amount of leftover sludge while at the same time producing fuel-grade hydrogen gas.
In most wastewater treatment plants—of which there are 16,000 in the United States—raw wastewater first goes into aeration tanks, which are seeded with microorganisms that digest much of the waste. The water then goes into settling tanks where the remaining sludge settles out. A small amount of this sludge is recycled back into the aeration tanks as seed material; the rest is dried as a solid that must be trucked away.
In recent years, a startup called Envirex developed a “sidestream reactor” that greatly reduces sludge volumes by cycling it back and forth between tanks full of aerobic and anaerobic bacteria, respectively; the bacteria basically eat each other up, which is why Siemens, which purchased Envirex, calls it the “Cannibal” solids reduction process.
Park says his team at UMass has developed a small continuously stirred tank reactor, or CSTR, in which the anaerobic bacteria are heated until thermal hydrolysis kicks in, producing hydrogen. Not only is the UMass design simpler and cheaper than the equipment needed for Siemens’ Cannibal process, but the hydrogen produced can help pay for the new equipment in just two years, Park says—and there’s 30 to 40 percent less sludge left at the end.
Nanotube-based Ultracapacitors for Electrical Grid Regulation
Though Riccardo Signorelli won’t get his PhD from Joel Schindall’s group at MIT’s Laboratory for Electronic and Electromagnetic Systems until June, he’s already got plans to become president and chief technology officer of FastCAP Systems. The company is commercializing “ultracapacitors” with electrodes comprised of vertically aligned carbon nanotubes.
Capacitors store energy in a pair of conductors separated by a dielectric layer; “ultracapacitors” are electrochemical capacitors that store a lot more energy. They’re mostly used to smooth out the supply of electricity in situations where power supplies are variable, but they’re also starting to be seen as an alternative to conventional chemical batteries.
In traditional ultracapacitors, according to Signorelli, the activated carbon material used for electrodes has low ionic conductivity, and must go through aggressive chemical treatment to prepare the surface, which lowers the devices’ ultimate voltage. The carbon nanotube-based electrodes his team has developed have much greater internal surface area, which makes them much more conductive, with less need for surface treatment. Ultracapacitors made with the carbon nanotube material can be operated at higher voltages, giving them up to five times the energy density of their conventional counterparts, Signorelli said.
The big target market for FastCAP Systems is electrical grid regulation. The 60-hertz frequency of the U.S. electrical grid must be kept constant at all times, with fluctuations of no more than 0.1 percent. To fill in for sudden interruptions, between 1 and 2 percent of the nation’s power supply must be kept on “spinning reserve” at all times. That amounts to between 8 and 16 gigawatts, at a cost of $3 billion to $5 billion per year. Much of this online generating capacity could be replaced by ultracapacitors, which would save fuel, reduce carbon dioxide emissions, and allow power producers to sell some of the spinning reserve, Signorelli said.
The market for electrical grid regulation systems, such as Tyngsboro, MA-based Beacon Power‘s flywheel power storage technology, already amounts to $1 billion a year, and will only get bigger as highly variable power sources such as wind farms and solar facilities come online, he said. FastCAP Systems wants to grab a slice of that market—but could also supply technology for hybrid battery/ultracapacitor-powered cars and trucks. The company is a semifinalist in the MIT Clean Energy Prize Competition; the $200,000 grand prize in the competition will be awarded May 12.
