Muck makes fuel: a Florida firm turns algae to diesel, but the problem is the cost

The green muck in your pool might someday be a source of fuel for your car, but not just yet.

Although there's been a surge of interest in biofuels that has sent companies racing to be the first to produce cost-effective algae fuels on a large scale, algae fuels remain mired in unforgiving economics, notes today's St. Petersburg Times.

But a Florida company, PetroAlgae, hopes its technology will provide the needed breakthrough to make algae the fuel of the future. Formed in 1996, the Melbourne-basec ompany licensed technology from Arizona State University.

Featured in Time magazine last year, PetroAlgae has grown to 91 employees. Company vice president Fred Tennant hopes to complete a 20-acre demonstration farm early next year.

The real challeng isn't the manufacturing process, explained Tennant, but the price. "No one needs another high-priced fuel," he said. "If we make biodiesel out of this and it's 21 bucks a gallon, no one is going to buy it."

[St. Petersburg Times photo of algae by John Pendygraft]

 

--Asjylyn Loder

Comments

[paminator]

About 8% is the maximum theoretically achievable efficiency of photosynthesis in a laboratory cell, and 1-2% is more typical for plants that love sunlight (Hoffert et al, Scientific American Compass article, 2002 has more numbers on all sources of energy). If Algae needs to be shielded from direct sunlight, then the vertical growth arrangements of closed growth containers are the only way you could capture most of the available solar insolation. For comparison, commercial solar PV farms are about 12% efficient at making electricity, and solar thermal can be as high as 15-20%.

My guess is that commercial-scale Algae farms will have efficiencies far below 1% when a complete energy budget is properly carried out on a commercial scale design. DOE demonstrations in the 1990's came in at about 0.3%. At 5 kWhr/m^2/day average insolation in sunny Florida, which from personal experience is an excellent location for growing all types of Algae, a 1% efficient algae farm would produce 50 Whr/m^2/day of energy in the form of fuel. That is 0.18 MJ/m^2/day. At 34 MJ/liter for biofuel, that is 5.3 ml (about 100 drops!) of fuel per m^2 per day. An acre is 4047 m^2. So we get 21.5 Liters of fuel per acre per day, or 7830 Liters per acre per year, or 2066 Gallons per acre per year. Even at an impossibly high 8% efficiency, its 16,500 Gallons per acre per year, nowhere near 100,000 Gallons per acre per year claimed by some start-ups.
For a backyard system covering 1,000 square feet, you could produce (at 1% efficiency) about 1 Gallon per week.

This does not address the cost of growth, extraction and refining into useful fuel.