RWE plans to generate electricity from algal diesel

By Susanne Retka Schill
Posted October 16, 2009 at 9:11 a.m. CST

Renewed World Energies Corp. has begun work on a five-acre site to turn algae biomass into green diesel and electricity at Georgetown, S.C., with a goal of being in production by late 2010. Between three and four acres of photobioreactors are planned to produce algae-based fuels to generate electrical energy. "The quickest way for generating revenues is in producing electricity," said Rick Armstrong, co-founder of RWE. He and fellow co-founder Tim Tompkins unveiled their system at the Algae Biomass Summit in San Diego, Calif., the first week of October.

Armstrong and Tompkins applied their experience in automation and process control to develop what they believe will be a cost-effective photobioreactor. Armstrong said their projections show a 12.8 percent return on investment for a 1.6 megawatt (MW) unit, while a larger 5 MW system should provide a return on investment closer to 15 percent. An individual photobioreactor panel measures 4 feet wide by 6 feet high by 3 inches thick, with 550 panels contained in one cell and five to six cells covering an acre of land. The process utilizes automated harvesting, reducing the moisture content in a prescreening process to about 20 percent, before being pumped to a final screen and dried further if necessary prior to processing. The estimated yield per acre is between 95 and 125 tons of dried biomass per year, according to Armstrong.

RWE plans to use the algae produced at its Georgetown facility to fuel a green diesel biomass refinery under order from Unified Fuels. The catalyzed gasification unit has four products-the greatest proportion being a liquid green diesel, a smaller proportion of green gasoline, non-condensable gases dominated by methane and ash. RWE's facility will include two 800 kilowatt generators, one a natural gas generator modified to burn the methane and the other a reciprocating engine to burn the green diesel. The generator exhaust will be recycled through the system. Negotiations for a purchase power agreement are nearing completion with the regional utility, Santee-Cooper Electric, Armstrong added.

One of the goals of the design, Tompkins added, was to build a system that could be adjusted to create the optimal conditions for any strain of algae. "We found there has not been a lot of work done on the automation and process control side of photobioreactors," Armstrong added. While the cost of a photobioreactor is higher than an open pond system, he said that is offset by an increase in yields from being able to control the environment, plus the ability to contain the greenhouse gases (GHG) being used as algae nutrients. Target markets for the system are electrical utilities and industries with emissions that could fuel the algae system, reducing GHG emissions while generating additional power and biofuels.

A group of investors backed the development of the project through the prototype stage, with another round of fundraising ongoing now. "It hasn't been as successful as I'd like it to be," Armstrong said. "We've had enough to continue working. We've been very frugal. We've spent less than $4 million so far." The company is working on a joint venture to build a second system similar to the South Carolina facility with Southland Renewable Fuels LLC, Paducah, Ky.