Here’s my newest offering for the Our Green Earth website. I actually wrote this article before Christmas but it’s only just been posted. The topic this time is something that I was berated for missing out of my first ever OGE article about alternative fuel sources; the potential of algae for the production of biofuels. Enjoy!
[Edit 3rd December 2010: Sadly, Our Green Earth no longer exists but the owner has very kindly handed back copyright of my articles to me. Here, for your reading pleasure, is Algae as a Feedstock for Biodiesel Production…]
Algae as a feedstock for biodiesel production
When I wrote the article “New Biofuels Research: Watermelon Bioethanol Production”, the company I work for (BioMed Central, to get in a quick plug!) posted a link to it on their Facebook page. The link generated quite a few comments – mostly positive, I hasten to add! – but one berated me for not considering the use of algae as an important source of biofuels in my article. Of course, I couldn’t hope to cover every piece of new research in this area in one article, but she had a point – the growth of algae in the development of biofuel is an important and emerging area of research, so here’s an article to make up for it!
Animal, vegetable or mineral?
Algae are an oft misunderstood organism. They are frequently mistaken for plants since they are often green, are capable of photosynthesis and can look very much like plants (for example, seaweed). Actually, algae are classified these days as belonging to the phylum protista – complex-celled organisms that have characteristics not found in either plants or animals. Algae can be single-celled or multicellular, and to make matters even more confusing, a subset called the blue-green algae are no longer classified as being algae at all; rather they are called cyanobacteria.
It’s not easy being green
As well as being misunderstood, algae also have a bad reputation. They are blamed for the process of eutrophication – a phenomenon whereby rapid algal growth in bodies of water such as lakes can deplete the oxygen supply, thus killing fish and other aquatic life as well as creating an unsightly looking scum on the water’s surface. However, these algal blooms are the result of eutrophication rather than the cause, since their growth is a response to the presence of high levels of agricultural fertilisers that leach into the water from nearly farmland.
Old ideas, new research
The speed and ease of algal growth however, may one day be used for the greater good. Algae are very good at storing fatty oils, which in turn could be used instead of rapeseed, canola, palm or soy plants as a feedstock to produce biodiesel. This is not, in fact, a new idea. The National Renewable Energy Laboratory of the United States initiated research in this field as long ago as the 1970s, yet the project was shelved in the mid-1990s when the price of oil fell so low that it was not thought to be worth the investment. In more recent times, however, as research into renewable energy steps up again, scientists around the world, as well as energy companies, are investing time and money into the development of algae technology on a commercial scale.
Advantages of algal biofuel production
Therein lies the problem of this technology – the scale of production. For all intents and purposes, the production of biodiesel using algae seems like a miracle solution to the world’s rapidly decreasing fossil fuel resources. Algae have a significant advantage over plant crops because they takes up very little space that could be better put to use to grow food crops or to graze livestock. They can be cultured very quickly in ponds of water – even brackish, saline or waste water, and have been reported to yield up to 6000 gallons of fuel per acre per year – significantly more than other feedstocks (palm yields 650 gal/ac/yr; canola, 150 gal; and soy, 50 gal) (1).
Reducing CO2 emissions with algae
Because algae are effective photosynthesisers, it has also been suggested that “oilgae” producers could join forces with fossil fuel burning factories and power stations to “mop up” excess CO2 and thus reduce carbon emissions. Producing algal biodiesel on a large enough scale to be commercially viable, however, is expensive – at the moment, prohibitively so.
Current technology: the cheap method
There are two main ways to grow up enough algae to use for biodiesel. The first is to grow them in open ponds that are cheap and use much less land than plant feedstocks. In addition, the ponds can be placed on non-arable, unproductive land where they do not directly compete with space required for food crops (2). However, the algal ponds can be easily contaminated with invasive species, which significantly limit the yield.
Current technology: the expensive option
For this reason, the current preferred method of algae cultivation is to use specially engineered photobioreactors; devices which supply the algae with all the nutrients they need to grow well in sterile conditions, while also being programmed to heat and cool the algae as required for growth, fermentation and other energy-dependent processes. Closed systems are much more controllable than leaving the algae exposed to the elements, and are capable of yielding much greater quantities of biofuel, but, not surprisingly, they are expensive and some researchers question whether the energy expended during the production process can really allow us to call it a “green technology”.
Hope for the future
Many researchers remain optimistic. Paul Woods, chief executive of the biofuel start-up Algenol Biofuels, says, “I’m a believer that we’re one, two, and three years away from having this on a commercial scale” (1). New engineering research by Johnson and Wen (2) has succeeded in the development of a prototype that uses an attached microalgal growth system, rather than a free-living culture. This has shown promise in reducing some of the costs involved in algae culture. Other have approached the problem from a different angle by experimenting with different wastewater supplies, for example from dairy farms (3) and household sewerage (4), or by trying to genetically engineer a “perfect” strain of algae that will produce optimum yields of oil (5).
It remains to be seen what will come of this research in real, every day terms, but it is certainly exciting and scientists are hopeful that we will see results in just a few years. In fact, China has already reportedly signed a deal with the biofuels firm PetroAlgae Inc. to build 10 commercial algal biodiesel plants (1). If the technology can indeed be developed to make algal biofuels a genuinely green, commercially viable fuel, that will reduce greenhouse gas emissions and help to preserve our planet and its precious natural resources, then I’m all for it.
- Mascarelli, AL, Algae: fuel of the future? Environmental Science and Technology 43:19 pp 7160-7161, 2009
- Johnson, MB and Wen, Z, Development of an attached microalgal growth system for biofuel production, Applied Microbiological Biotechnology, 2009
- Woertz, I, Feffer, A, Lundquist, T and Nelson, Y, Algae grown on dairy and municipal wastewater for simultaneous nutrient removal and lipid production for biofuel feedstock, Journal of Environmental Engineering 135 (11), pp. 1115 – 1122, 2009
- Wang, L, Min, M, Li, Y, Chen, P, Chen, Y, Liu, Y, Wang Y and Ruan R, Cultivation of Green Algae Chlorella sp. in Different Wastewaters from Municipal Wastewater Treatment Plant, Applied Biochemistry and Biotechnology, pp. 1-13, 2009
- Yoon, JY and Riley, MR, Grand challenges for biological engineering, Journal of Biological Engineering 3:16, 2009