Mr. Green Car: Is there a slime pond in your future?
By Allen Penticoff
First of all, I hope everyone had a merry Christmas and is looking forward to a prosperous New Year.
Back to biofuels. The last two Mr. Green Car columns were about biodiesel and plants that produce oil. We’ll continue that vein, and look at the future of farmed fuel with an exploration of algae-sourced fuel.
What I’ve found so far is that there is a great deal of promise in algae, but so many technical and economic hurdles that we may not see common usage unless there are some breakthroughs.
Most of the research is focused on micro-algae, those that are very small, your typical backyard pond scum.
This is quite unlike macro-algae, of which seaweed is a type, though the latter holds some promise, too.
Algae can be grown in waste-water-treatment-released water, where there are many nutrients, and it can be grown in saltwater and water with high salinity, freeing freshwater sources from energy production needs. To “turbo-charge” the growth of algae, a source of clean carbon dioxide is necessary. Some experiments have shown that smokestacks may be a good source of carbon dioxide. Thus, algae production facilities may be co-located with power plants and other smokestack industries, with the obvious benefits of cleaning their air while turning it into fuel.
Algae can be grown in tubes, called bioreactors or photobioreactors (PBR). These closed systems require that nutrients and carbon dioxide be pumped through them, but they have the advantage of remaining nearly sterile, with little exposure to other strains of algae, viruses or other pollutants.
Most research is being conducted in PBRs. However, it is apparent this is the most costly way to grow oil-producing algae. Open pond systems can be created and operated at far lower costs, but they have not yet been very successful with them. To grow a mono-culture algae in an open pond system, the algae strain needs to be very resilient to the airborne problems mentioned earlier, and this has proven to be problematic.
Algae that have lower oil yields do better in open pond systems. Thus, the trade-off may be the expensive, closed, high-yielding crop, or the very large, lesser-yielding crop. Compared to more common field crops, algae can be harvested every one to 10 days. Thus, it is claimed algae may be able to produce vastly more oil per acre than conventional crops.
Algae would be a good crop in arid, sunny areas with poor or drought-stricken soil and high salinity in the water supply, thereby not being in competition with food crops for land use. Algae grown in tubes could be grown in nearly any place with access to the carbon dioxide and nutrient-rich water and sunlight they need.
I have also found that after the algae has its oil extracted, the biomass that remains can be processed into other transportation-friendly products, such as Biobutanol, which is very similar to gasoline and is claimed to run in gasoline engines without modification and when blended with gasoline. Biobutanol also provides better performance and corrosion resistance than ethanol or E85. Biogasoline can be made from algae and similar biomasses. And methane can be made from the decomposing algae, too—an energy source we are now harvesting from our landfills to heat homes, produce electricity and power vehicles.
Two companies—Solazyme and Sapphire Energy—are making “Green Crude” from algae. The oil is similar to light, sweet crude, and can be refined as mineral crude is, by hydrocracking into fuels such as gasoline, diesel and jet fuel.
Sapphire Energy provided 50 gallons of biogasoline (5 percent algae gas) to drive a plug-in Toyota Prius, Algaeus, across the U.S. in September 2009, promoting the documentary film Fields of Fuel (sometimes called just Fuel). Sapphire Energy’s goal is to produce 1 billion gallons of algae fuel by 2025. Solarzyme uses a different process, and has a diesel Mercedes run on its fuel to promote the film as well.
Also, bioplastics can be made from plants, their oils and biomass. Bioplastics are also biodegradable—some of which are in the marketplace right now. (It is my belief that, if you do have biodegrable plastics, dispose of them so that they go to the landfill to decompose. Eventually, the methane gas from them decomposing can be used as a fuel. They will not decompose in your garden.)
As I said in my last column about nature’s fuel, the most effective use of plant-generated oil, algae included, is to use it in a diesel engine that has been modified to operate on straight vegetable oil (SVO). In this manner, the lesser amount of additional energy, processing, chemicals and residual product there is to deal with. Grow, squeeze, drive is about all it takes.
Encouraging as “Green Crude” is, we probably will not be seeing much impact in the near term with mineral oil prices being held in check by the world economic recession. A few breakthroughs here and there may change that picture, though—and you never know when one will come along. A lot of companies and governments are trying to make green fuel happen.
From the Dec. 30, 2009 – Jan. 5, 2010 issue