As we inch closer towards a post-carbon economy, the future mix of energy sources is slowly bubbling to the top. One potential addition to this mix is the large-scale production of oil-containing algae. Jamais brought GreenFuel to our attention last year, but, as with most things in the sustainability realm, the momentum behind algae has grown tremendously since then. New companies, new methods, and a changing landscape indicate that biofuel from algae is poised to play a larger role.
Unlike crops that are currently being using for oil production such as soy, palm, corn and jatropha, some strains of algae contain as much as 50% oil. Once algae is grown, harvested and pressed to extract the oil, the remaining residue can be processed into ethanol, or burned directly in a power plant. The oil can then be processed into biodiesel using the ethanol (or methanol from another source). The National Renewable Energy Lab also believes jet fuel from certain strains of algae is possible.
Algae needs just a few simple things to kick-start a happy, oil-bearing life: water, sunlight and nutrients. While these might seem abundant and easy to come by, scientists and engineers who have been working in this area wish it were only that easy. The Aquatic Species Program, funded by the U.S. Department of Energy, tried for 20 years to find the optimal species for algal oil production. The program was unfortunately cut short when diesel prices bottomed out in the mid-1990's.
The July 1998 close out report from the program concluded that even with the most optimistic lipid yields the production of bio-diesel from algae would only become cost effective if petro-diesel prices rose to twice the 1998 levels. (October 2006 oil prices are three times higher than the average 1998 price in constant dollars).The program’s database of algae species and their characteristics have proven very useful for companies in the private sector who have realized the potential that algae has as a fuel source. Commercial algae production, however, is still in a nascent stage with only a handful of companies deploying their respective technologies on a large scale. There are two main types of technologies for mass-producing algae for conversion to biodiesel.
Photo Bioreactors:
This type of technology implements a closed system that introduces carbon dioxide to the algae to enhance its growth in the presence of light, water and nutrients. GreenFuel's Emissions-to-Biofuels technologym (previously featured here) is a system where CO2-rich flue emissions feed into tubes filled with water and nutrients where the algae are suspended. The rapidly growing algae is continuously removed from the system. The technology first rolled-out at the MIT power plant, and in the next 18-24 months several pre-commercial pilot projects will follow around the world. CEO Cary Bullock hopes this next phase of implementation will lead to the installation of hundreds and perhaps thousands of acres of algae systems.
The GreenShift CleanTech system, born out of the work of David Bayless of Ohio University, uses solar collectors to concentrate sunlight. The system then pipes the light into a closed chamber and distributes it over glow plates with a large surface area enriched with CO2 from a nearby power plant. Between the glow plates are growth media, over which water and a nutrient solution flow, and algae grow. When the algae are ready to harvest, an increase in water pressure separates them from the growth media for collection. A very neat animation and description of their technology is available here.
Solix Biofuel in Fort Collins, Colorado has partnered with Colorado State University to develop an alternative bioreactor. While most of the other set-ups take CO2 from power plants, the Solix demonstration site sits adjacent to a brewery where the fermentation process yields enough CO2 to feed the algae. Long, narrow tanks sealed with plastic sheeting contain algae, water, nutrients, and CO2 that are pumped in from the nearby brewery. In order to ensure that the algae have sufficient light, a roller passes back and forth over the tank to mix the contents.
Open Pond:
The other common method to cultivate algae uses an open pond design. Open ponds, such as Aquaflow Bionomic's in New Zealand, use carbon and nutrient rich effluent streams from waste water treatment plants to grow their algae. Unlike the closed photo bioreactor, enough carbon is present in the effluent stream that additional CO2 doesn't need to be added. While currently under development, Aquaflow hopes that the process will sufficiently filter the wastewater for re-use in other applications like irrigation. To demonstrate the potential of their technology, the company drove the energy minister of New Zealand around using a B5 blend of their algae-based biodiesel.
Whatever method or methods ultimately prove most efficient, Narsi Santhanam of oilgae.com believes that the key to a successful algae industry lies in finding optimal algae strains, proper technologies for growth/culturing, and efficient oil extraction. Cary Bullock of GreenFuel understands the necessity to lower current production costs to be competitive in the larger market, and sees bountiful opportunities to cut costs by harnessing carbon and heat from manufacturing facilities and power plants.
Similarly, our colleague Matt Johnston believes that technological hurdles are hampering algae from breaking through to become a substantive force in the renewable energy generation portfolio. He points to companies like Earthrise that specialize in producing spirulina algae in large, open raceway tracks for sale in the natural food market at many times the price of algal biofuels. While the production methods are a bit different for spirulina as industrial exhaust or effluent can't be used for consumer products, existing technologies already show promise for closing the gap between algal biodiesel and dino-diesel.
If algae biofuels become economically competitive, they an advantage over more radical options like hydrogen fuel cells by fitting into the existing transportation infrastructure. And unlike food crops like corn or canola that at most yield several hundred gallons of biodiesel per acre, potential algal yields of 15,000 gallons per acre mitigate worries that algae will compete for land we currently use to grow food.
Michael Briggs of the University of New Hampshire estimates that the entire transportation needs of the United States could hypothetically be met with just 9.5 million acres of algae farms--about 15% of the urban land area in the US and a little more than all urban land added during the 1990's. This is a fathomable area to be sure, and an amount dwarfed by agriculture, but it's also enough so that we should be mindful of potential land-use consequences.
The land devoted to algae farms would require a reliable stream of nutrients, water, and carbon. Jamais calculated that 1600 giga-watt power plants converted to algae production could manufacture enough ethanol and biodiesel to replace the US annual consumption of 146 billion gallons of gasoline. Replacing convention diesel too would increase this requirement to over 2000 giga-watt sized power plants—or twice the number of suitably located major plants. Smaller facilities or other industries might conceivably close the gap.
Although recycling carbon from power generation for transportation would be a huge advance, Jamais cautioned that it could slow the transition to a truly sustainable economy by prolonging dependence on fossil fuels. A 50% emission reduction would no doubt be a great victory, and one we would likely accept from anything less uncharismatic than coal. Any net carbon emissions to the atmosphere, however, are unsustainable in the long run.
Whether or not an algae-economy would ultimately slow the transition to zero-emissions could depend on the legal and economic mechanisms used to allocate emission reductions. If, for example, we enact a carbon tax or cap and trade system, who will pay the tax or get the credits, the people driving cars or the ones running power plants? And how will these shifts in green power play out politically under Kyoto or some other legislation? If, for instance, new legislation assigns the benefits of emission reductions to algae biofuels instead of power plants, cheaper biofuels might pose a barrier to fuel cells or advanced battery vehicles. By contrast, if those same benefits instead go to power plants, they could conceivable undercut the price of wind power or emerging sources of renewable energy.
These non-technical questions are in some ways the most difficult ones, and although they might not have as clear of an answer as the kinds of questions we can ask about R&D, they are every bit as important to ensuring that algal biofuels, or any potential technology for that matter, contribute to a sustainable future.
Algae's dearest contribution might not be just in reducing carbon emissions but rather in offering a viable holistic approach to integrating waste and resources. How brilliant is it to turn the industrial waste products from brewing beer, making concrete produce CO2, or burning fossil fuels into clean, green energy? And on top of that, some systems promise turning dirty, nutrient filled sewage into fresh water. This is the kind of industrial ecology that we need to think harder about that nests cycles within cycles to optimize across a slew of difficult problems at once. Better ways to turn waste into a revenue stream and low-carbon energy, while at the same time mitigating air and water pollution, is a win-win situation for producer, consumer, and the environment.
(Thanks Matt, Vicki, Marc, Cary and Narsi!)
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