Focus on the Environment: Oil from algae - a promising alternative to fossil fuels

Monday, October 5, 2009

Commercial cultivation of algae to produce oil and other usable byproducts is looking increasingly viable. And there's no reason why Ontario farmers can't participate

by PETER ION

The ancient Greeks ate it in large volumes, the 18th century Scots extracted the chemicals from it as it washed up on their windswept shorelines, and now it seems that 21st century internal combustion engines might be run on the stuff. Oil from algae – "oilgae" to some – has become a real prospect in the ongoing battle to find viable alternatives to ever-decreasing fossil fuels.

As the first airlines completed test flights powered (in part) by algae-derived aviation fuel over Tokyo Bay and the Gulf of Mexico this year, there is now no remaining doubt about the capabilities of phytoplankton to deliver a sufficiently high grade product. Whether or not it is commercially viable, El Paso-based Valcent Inc. is now producing credible data on its capabilities – 10,000 gallons per acre per year.

This is significantly rounded down from their early estimates of 150,000 gallons, but still impressive enough compared to the capabilities of corn, soy and palm crops, which averaged out at 18, 48 and 600 gallons per acre per year respectively. Producer Greenfuels Inc. Cambridge, Massachusetts estimates its capabilities at 5,500 gallons per acre per year. 

Open system algae farms are ideally placed to evolve synergistically with heavy industry. A power plant generating electricity also delivers heat and a steady stream of waste CO2 – two of the three basic requirements for algae to thrive. A certain level of light intensity is the third.

Algae's ability to utilize the high phosphates and nitrate levels of waste water and sewage treatment outlets makes siting algaculture farms in close proximity more viable also. Even industrial plants that generate a rich waste stream of CO2 intermittently (such as a cement-producing plant) could serve algae farming effectively. Removing the CO2 source periodically is a means of causing the algae to flocculate, a necessary pre-harvesting process.

Left to their own devices, algae are natural competitors. Laboratory trials in recent years have been successful in identifying the concept of "critical light intensity" as the limiting factor in their growth. Different strains can co-exist, but a dominant algal strain will evolve in any "open" system (such as a raceway pond) where a certain light intensity is available. Algae only utilize about 10 per cent of the available light within the spectrum, but are particularly effective in doing so, typically doubling their mass in the course of a day.

Ontario's sunshine may not be as intense as that in the southwestern United States, where much of the energy of algae farming has been invested at scales likely to drive the industry forward, but that is proving to be no hindrance.

Low levels of light intensity are preferable for many strains (it is proven that, in some strains, growth is actually inhibited by high levels of light intensity). Once a layer of 10 centimetres is formed, it will effectively starve itself of light and limit its own growth.

The transition to closed system production is proving a viable alternative with Ontario organizations at the cutting edge of algaculture. Ottawa-based Menova Inc. recently received funding through federally-supported Sustainable Development Technology Canada to assist the development of their photobioreactor design.

This functions as a solar collector, channelling and redirecting incident sunlight vertically downwards, providing algae at lower layers in the water column with solar energy that otherwise would be self-absorbed at the surface.

Valcent's High Density Vertical Bioreactor system is a one-stop turnkey system for the cultivation of algae on a commercial scale. It is openly marketed as a small footprint design ideally suited to installation on unused parcels of land where a CO2 source can be harnessed. Valcent is keen to highlight the potential for qualification for carbon credits under the Kyoto Protocol mechanisms, but American users are excluded, at least until the Obama administration should sign up to Kyoto.

At the time of writing, no algae-based projects had been officially approved within the Clean Development Mechanisms whereby carbon credits may be earned or transferred. As with other biomass-based techniques, such as biochar production, the technology typically goes through a demonstration phase before being admitted as a qualifying process. This is very likely to happen at the Copenhagen meeting in late 2009.

As a viable productive process it is one of the most efficient in existence.

In the mid-1990s, U.S. researchers at the National Renewable Energy Labs concluded that, under controlled conditions, typically 90 per cent of waste stream CO2 fed into trial tanks was utilized by the algae. Further research has succeeded in demonstrating techniques for getting the algae to over-express the ACcase enzyme that controls fatty acid synthesis. However, increased oil production in the algae cells is not automatically achieved.

Extracting the oil from the harvested algae is also proving an engineering challenge. Simple mechanical press designs are successful in expelling about 75 per cent of the oil.

Recovery efficiencies can be increased with chemical treatments. Hexane solvents have been applied to boost the percentage recovery of refinable oils, but incur higher costs and have an impact on the environment. Enzymatic extraction uses enzymes to degrade the cell walls with water as the solvent. Fractionation of the oil is easier but more expensive than hexane solvent processes. Osmotic shock processes (in which the algae is exposed to a sudden change in pressure) can cause the cells to rupture and release the oil component.

More expensive still are ultrasonically-assisted extraction techniques in which high frequency waves are applied that create cavitation bubbles in a solvent material. At the extreme end, a process called supercritical fluid extraction can extract almost 100 per cent of the oils, but involves heating CO2 to its liquid/gas state, at which point the full carbon-cost of the process becomes self-defeating.

The route to market for "oilgae" is still being impeded by production costs. Theindustry's own proponents are citing a figure of US$33 per gallon for raw production. A figure of US$11 is attributed to some solvent-based extraction techniques. The critical component is the ability to harness waste heat and CO2 streams, which they say will reduce this to $6.

A further reduction to $4 is achievable through the use of by-product materials from the algae paste – nutritional supplements for human consumption and animal feeds, sterols used as building blocks in the pharmaceutical industry, and biomedical uses in anti-viral and anti-cancer compounds. (With petroleum-based diesel currently sitting at the $2 level, there is still some ground to be made up.) However, cost barriers will be eroded by mass production.

In late 2008, Solazyme Inc. (USA) projected the capability to deliver "millions of gallons within three years." Its successful jet fuel trials this year were based on algae grown on farm-derived waste biomass – in total darkness, they claim. Ontario's farm waste and winter darkness could be a fertile combination for algal cultivation.

Substituting sugars for solar input as the key ingredient has also proven viable in recent years, so the range of production could extend beyond the sunshine states and provinces.

The business case for the technology is in a state of flux at the moment. This year, Greenfuels Inc., one of the first movers in this field, put their intellectual property up for sale and invited bidders. Ontario producers might be advised to take a close look at their key findings, in particular that algal farms have the potential to produce (other than algal oil for refining to fuel) both delipidated algal meal and dried whole algae that are suitable for a variety of animal feed applications.

As one door closes, it would appear that another may be opening. In July of this year, an industry partnership was set up between Exxon and genomics pioneer Craig Venter to produce algal oil, albeit with a focus upon delivering a pure hydrocarbon product rather than byproducts such as fertilizers.

In the years ahead, it is likely that national carbon budgets will be managed with algae as a key component. Geological CO2 sequestration is gaining acceptance and the notion of placing extensive raceway ponds above the injection areas to naturally absorb any seepage is not as fanciful as it may appear.

Vast tracts of unused and low quality unfarmable land along easily accessible freeway shoulders could be infilled with waste water streams, screened for odour and periodically harvested of algae. In the drive to energy independence and stability in food pricing, farm-grown "oilgae" could help lead the way. BF

Sidebar: Huron County a battleground

The beaches near Goderich are a battleground between cottage owners and farmers in one of Ontario's most productive agricultural counties.

Wayne Black, president of the Huron Federation of Agriculture, thinks DNA testing of bacteria on the beach will be good thing as long as it is perfected and the results are properly interpreted.

Black, who farms near Auburn, says he spends half of his time as county president dealing with the fallout over a study of bacteria found on the beach near Eighteen Mile River, north of Goderich. The study has been taken out of context, but local cottage owners who opposed large livestock operations "are holding it up like the Holy Grail," says Black. "They said that the Eighteen Mile study was representative of the entire lakeshore." Cottagers want to use that study to set policy for all of Huron County, he argues.

In May, University of Guelph land user professor John Fitzgibbon, who is chair of the steering committee of the Ontario Farm Environmental Coalition, re-iterated that the study, published in the March issue of the Canadian Journal of Microbiology did not condemn "big barns" as the source of E. coli, in streams and on the beaches. The watershed contains many livestock farms and no human settlements with sewage treatment plants.

Fitzgibbon also described the library of known bacteria to compare against samples found in the stream as "a little bit thin."

The study was funded by the Best in Science Program of the Ontario Ministry of the Environment.

DNA testing of bacteria found on beaches "is not a perfect science yet," Black says. BF