Compared to Gasoline
Algenol is working on making ethanol from algae in photobioreactors connected to power plants. Like with all types of biofuels, the most important question with algae-ethanol has always been: Is it really greener than fossil fuels? And if so, how much? A team from Algenol and Georgia Tech tried to answer that question by doing a life cycle analysis (LCA) on the whole process of making Algenol's ethanol, and the results were published as an open access paper in the ACS journal Environmental Science & Technology.
The process that was modeled envisioned cyanobacteria grown in flexible-film, polyethylene-based photobioreactors containing seawater or brackish water as the culture medium. To provide sufficient carbon dioxide to support efficient algal growth, the production facility is located near a fossil-fuel power plant or industrial source of carbon dioxide. The study's calculation was based on use of industrial CO2, such as the byproduct CO2 from ethylene oxide production. [...]
They found that, on a life cycle basis in comparison to gasoline, the direct to ethanol technology can provide a 67% to 87% reduction in carbon footprint on an energy equivalent basis for initial ethanol concentrations (given in weight percent) ranging from 0.5% to 5%.
Is it Enough?
That's a significant reduction, though we can wonder how it will compare to what will be available by the time this can scale up. By this I mean, how does it compare to CO2 emissions from electricity used in electric vehicles?
Let's not kid ourselves, combustion engines will be around for a while, so it will be a good thing if truly green biofuels are available. But electric cars are truly more efficient, and if electricity generation can more efficiently capture renewable energy sources than growing algae (which probably has a solar energy conversion efficiency of a few percents, and then a lot more energy is wasted in the internal combustion engine), we should probably focus on developing these technologies.
What will matter most is how fast production of algae biofuels can scale up. If it can do so rapidly, it can help bridge the transition to fully electric vehicles.
Via ACS, Green Car Congress
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