Power from bacteria
New processes to harness algae’s eletrodes and methane’s energy.
RESEARCHERS this week announced two advances in power generating that may yet impact on transport.
At the Concordia University in Montreal, researchers have invented a power cell that harnesses the electricity created during the natural processes of photosynthesis and respiration in blue-green algae.
And at the Institute of Advanced Sustainability Studies (Iass) and Karlsruhe Institute of Technology (Kit) have developed a process that extracts the energy content of methane, in the form hydrogen, without producing carbon dioxide.
The journal Technology quotes Concordia engineering professor Muthukumaran Packirisamy: “By taking advantage of a process that is constantly occurring all over the world, we’ve created a new and scalable technology that could lead to cheaper ways of generating carbonfree energy.”
Blue-green algae, which is actually cynobacteria, is also touted as possible source of biofuel.
The Concordia group report their prototype photosynthetic power cell measured open-circuit voltage of up to 993 millivolts, while a peak power of 175 microwatts was obtained under an external load of 850 ohms.
Packirisamy hopes the photosynthetic power cells could soon be used to power mobile devices and computers and perhaps eventually become a major source of energy worldwide.
In the U.S., meanwhile, researchers are looking at cheaper ways to milk methane for its energy (hydrogen) to meet the American’s demand for natural gas, which accounts for over 28% of U.S. energy consumption.
Methane gases are produced wherever plant materials are rotting or have rotted, such as coal mines, but also by livestock, rice paddies and even termites.
Kit adapted an old process called “methane cracking,” which separates the hydrogen and carbon molecules at temperatures of over 750° C, by designing a small new reactor design based on liquid metal technology, and made of quartz and stainless steel.
Professor Thomas Wetzel of Kit, said the reactor produces hydrogen with a 78% conversion rate at 1 200° C, and can run continuously for two weeks.
Kit researcher Stefan Stueckrad said the team expect to spent until 2018 to research and develop an industrial prototype for a modular reactor, which could be scaled by simple multiplication.
Stueckrad added that the energy efficiency of the process “has been evaluated as slightly higher than conventional steam reforming of natural gas and about 20% higher than coal gasification” — assuming both employ carbon capture and storage.
The team’s research showed that methane cracking is comparable to water electrolysis, in regards to CO2 emissions per unit of hydrogen, and more than 50% cleaner than steam methane reforming technologies.
Preliminary calculations reveal that the technology could achieve costs of €1,90 to €3,30 (R29 to R50) per kilogram of hydrogen (at current German natural gas prices).
Critics however point out Kit’s new cracking process needs huge amount of energy, and unless solar power is used to make this power, their process will lead to CO2 emission being generated upstream.