For the average citizen, algae are often viewed as a problematic growth within backyard swimming pools and local rivers and ponds. On the other hand, algae are now a hot topic among environmentalists as agroindustrial developments see them being used to sequester carbon dioxide and produce biofuels. Algae can serve as a feedstock for biodiesel and ethanol. Since their basic requirements for growth include carbon dioxide, water, nutrients, and sunlight, using algae to produce biofuels can also help reduce carbon dioxide emissions at the same time as reducing the need for feedstocks that would otherwise be used for human consumption.
Indeed, some argue that algae could be perhaps the ultimate source of plant-based oil for biodiesel and ethanol, since it can flourish in otherwise hostile growing environments, including non-arable land, or in dirty water.
When algae flourishes, it is unmatched by any terrestrial feedstock known. Algae can double in mass several times daily. For example, with respect to estimating the number of US gallons of biodiesel produced from a variety of feedstock materials, algae is considered to be perhaps the highest in efficiency when compared to a variety of other crops. Algae will produce 1,800 to 15,000 gallons of biodiesel per acre (gpa): a huge amount compared to other popular biofuel feedstocks such as palm oil (508 gpa), rapeseed (102 gpa) and soy (59.2 to 98.6 gpa).
Greatest yield per acre
The US Department of Energy estimates that algae fuel can yield up to 30 times more energy per acre than land crops such as soybean, and a growing consensus suggests that biodiesel produced from algae is the only feasible solution today for replacement in full of petro-diesel products.
No other feedstock has the oil yield sufficient in volume to produce such large volumes of oil. To illustrate this point, in order to produce sufficient oil for biodiesel from crops such as soy or palm, all growing regions for all of today’s crops would have to produce simply soy (for example) to yield sufficient biodiesel for full replacement. Given the high oil yield from algae, some 10 million acres would however be sufficient – as land, pond, or ocean space – to grow enough algae to replace the total petro- diesel fuel in the United States today. This is about 1% of the total amount of acreage used in the United States today for grazing and farming; that being about 1% of one billion acres.
In the end, one could conclude that the vastly superior biodiesel feedstock material for the large scale replacement of petro-diesel is clearly algae. However, in order to produce large scale quantities of algae for such massive biodiesel projects, it is essential to have sustainable high oil producing strains of algae, on a large scale basis; followed by the ability to adequately extract the oil from algae on such a scale.
To follow, of course, there would need to be capabilities to convert algae oil into biodiesel. The first two steps are essentially specific to algae; and the final step is typical of all biodiesel processes related to all plant based oils.
Finally, the challenges of greatest need now are to define and refine the most viable strains of algae strains and develop/maintain the most effective and optimal cultivation methods.
Capturing carbon
But what other benefits do algae bring? Well, as mentioned at the start of this piece, algae can also be used to sequester or capture carbon dioxide at the same time as it is grown as a biofuel feedstock.
When a full loop or cycle is considered, algae require carbon dioxide to grow and thereby extract this greenhouse gas from the atmosphere as they grow. Algae can then be used in the manufacture of biodiesel and/or a feedstock for fermentation as ethanol. The production of biofuels leads to the creation of more carbon dioxide, which can then be pumped back into the cycle to boost algae growth still further. Effectively, this process kills two birds with one stone: curbing carbon dioxide emissions and creating more sustainable biofuels.
As a rule of thumb, approximately one ton of carbon dioxide would be removed (from otherwise airborne emissions) via the growth of two tons of algae. This offers us an extraordinary opportunity to reduce emissions, capture carbon dioxide, and foster new renewable energy technologies to replace diesel and jet fuels in the future.
Editor’s note: This is an edited version of an article kindly provided by Sam A. Rushing of Advanced Cryogenics, Ltd. Sam is a chemist with 30 years in the carbon dioxide industry, in both merchant and consultant roles. If you wish to contact Sam to find out more about his company’s work, send an e-mail to rushing@terranova.net or visit the Advanced Cryogenics website.
Retrieved from: Eco Periodicals
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