Hmm. Could this work? So far, all the algae energy hype has been just that, hype. Algae can give you a great biofuel, but just doesn't scale up. It's a "small is 'beautifuel'" thing. On Feb 25, 2014 11:22 AM, "Darryl McMahon" <dar...@econogics.com> wrote:
> http://www.maritime-executive.com/article/Continuous- > Process-Transforms-Algae-to-Biogas-2014-02-24/ > > Microalgae derived biogas is becoming an increasingly promising > alternative to fossil fuels. Over the past years, researchers at the Paul > Scherrer Institute (PSI) and EPFL have been developing SunCHem, a resource > and energy efficient process, to cultivate microalgae and convert them into > synthetic natural gas, a biofuel that is fully compatible with today's > expanding gas grid. In an article published in Catalysis Today, they > present one of the first continuous biomass to biogas conversion > technologies. > > While it takes nature millions of years to transform biomass into biogas, > it takes the SunCHem process less than an hour. The secret behind this feat > is a process called hydrothermal gasification. First, algae-rich water is > heated under pressure to a supercritical liquid state, to almost 400 > degrees Celsius. In this supercritical state, the water effectively > dissolves the organic matter contained in the biomass, while inorganic > salts become less soluble and can be recovered as a nutrient concentrate. > By gasifying the remaining solution in the presence of a catalyst, it is > then split into water, CO2, and the methane rich biogas. > > Although the approach is still about five to seven times too expensive to > compete with natural gas, microalgae evade much of the criticism that other > biofuel sources face. They can be grown in raceway ponds built on > non-arable land, without competing with agricultural food production. And > although the algae need water to grow in, they are not picky. Depending on > the species, they can grow in freshwater or saltwater, and in the future, > they could potentially even be used to treat wastewater. A study published > last year estimated that, for each unit of energy spent to produce the > biogas, between 1.8 and most optimistically 5.8 units of energy could be > produced. > > To save resources, cut costs, and increase the overall efficiency of the > process, the entire system can be run in a closed loop. "Some nutrients > such as phosphate are limited resources, which we can recover when we > gasify the biomass. Feeding them back into the water that we grow the algae > in has a spectacular effect on their growth," says Mariluz Bagnoud, one of > the two lead authors of the publication. > > For the publication, the researchers proved the feasibility of running the > system as a continuous process. But they also found that feeding back water > and nutrients over long durations leads to a degradation of the system's > performance. "We detected the deactivation of the catalyst used in the > gasification process and we expect the accumulation of trace amounts of > aluminum," says Bagnoud. "The toxicity of the aluminum on the microalgae > depends on the pH. By cultivating the algae at a neutral pH, these toxic > effects can essentially be eliminated," she says. "Now, the next steps will > involve fine-tuning the process to increase the longevity of the catalyst, > which is deactivated by the sulfur contained in the microalgae," she > concludes. > _______________________________________________ > Sustainablelorgbiofuel mailing list > Sustainablelorgbiofuel@lists.sustainablelists.org > http://lists.eruditium.org/cgi-bin/mailman/listinfo/sustainablelorgbiofuel > _______________________________________________ Sustainablelorgbiofuel mailing list Sustainablelorgbiofuel@lists.sustainablelists.org http://lists.eruditium.org/cgi-bin/mailman/listinfo/sustainablelorgbiofuel
