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Sewage and Cleantech

January 25, 2010


Like every other segment of the economy, the cleantech sector took a hit last year. Compared to other sectors, however, it fared relatively well — at least when it comes to attracting venture capital [“Clean tech gets big piece of funding pie,” by Julie Schmit, USA Today, 7 January 2010]. Schmit reports:


Venture-capital funding for clean-technology firms fell 33% in 2009 from the year before, but the sector fared better than others amid a dismal economy. … More than $5.6 billion in venture-capital investment went to clean-tech firms — including solar, wind, energy efficiency, transportation and biofuels — last year, say preliminary data from market researcher Cleantech Group and finance firm Deloitte. Total venture-capital investment has retreated to 2003 levels, but clean tech has reset only to 2007 levels, the Cleantech Group says. … In 2004, the sector accounted for about 3% of venture-capital investment. That expanded to about 25% in 2009. The sector last year, for the first time, received more private venture capital than any other sector, including software, Cleantech Group says.”


Just as the cleantech sector fared better than some other areas of the economy, some sub-sectors of cleantech also fared better than others. Schmit continues:


The top clean-tech recipient in 2009 was solar, which got 21% of it. But solar investment was down 64% from the previous year, while the transportation and energy-efficiency sectors had record years. The drop for solar stems from several factors, including the big amounts of money needed to commercialize technologies, says Dallas Kachan, managing director of the Cleantech Group. Meanwhile, energy-efficiency firms — those concentrating on everything from lighting to green building materials — often need less money to bring products or services to market, may rely on more proven technologies and may pose less risk to investors. ‘They’re not reinventing the wheel,’ Kachan says. Last year, venture capital for transportation — for such things as electric cars and new battery technology — rose 47% to $1.1 billion. Investment in energy efficiency rose 39% to $1 billion.”


In past posts about clean technologies, I’ve written about companies all over the world that are contributing research and innovation. Schmit reports that although North America still dominates the sector, that domination may be slipping. She continues:


The region is still dominant for clean-tech venture capital, but it’s getting a smaller share than it used to. Last year, North America received 62% of clean-tech venture-capital dollars, down from 72% in 2008, the Cleantech Group says. Europe and Israel took in 29% of 2009 dollars, up from 22% in 2008. That Europe and Israel increased their share of venture-capital funding may reflect the desire for investors to pursue less risky deals in markets where clean tech is already more widely deployed, Lesser says.”


Schmit’s article strictly dealt with the venture capital side of clean technologies. As I’ve noted in past posts, countries like China are also investing heavily in clean technologies; but many of the research efforts there are funded internally by corporations or by the government. Venture capitalists don’t get involved. Besides the obvious attraction for venture capitalists (i.e., clean technologies are generating government support), I believe that they are drawn to the sector because people in it remain creative. I’m thinking, for example, of the creative people who are trying to turn sewage into energy [“The seat of power,” The Economist, 2 January 2010 print issue]. I was drawn to article both by its tongue-in-cheek title and the equally amusing graphic that accompanied it. The editors might have taken the joke a bit too far, however, when they titled an accompanying figure, one showing how much energy is generated by sewage, “Flushed with pride.” The article begins:


Where there’s muck, there’s brass—or so the old saying has it. The cynical may suggest this refers to the question of who gets what, but thoughtful readers may be forgiven for wondering, while they are recovering from the excesses of Christmas in the smallest room in the house, what exactly happens when they flush the toilet. The answer is encouraging. Less and less waste, these days, is actually allowed to go to waste. Instead, it is used to generate biogas, a methane-rich mixture that can be employed for heating and for the generation of electricity. Moreover, in an age concerned with the efficient use of energy, technological improvements are squeezing human fecal matter to release every last drop of the stuff. Making biogas means doing artificially to faeces what would happen to them naturally if they were simply dumped into the environment or allowed to degrade in the open air at a traditional sewage farm—namely, arranging for them to be chewed up by bacteria. Capturing the resulting methane has a double benefit. As well as yielding energy, it also prevents what is a potent greenhouse gas from being released into the atmosphere.”


Discussing human fecal material may sound unpleasant (I hope you haven’t just eaten), but all organisms, including humans, generate waste. Dealing with that waste, if only for health reasons, is of significant importance. To learn more on that subject, read my post entitled Infrastructure and Disease. Turning sewage into energy opens entirely new ways for communities to foster energy security. The article continues:


Several groups are testing ways of making the process by which faeces are digested into methane more efficient. GENeco, a subsidiary of Wessex Water, a British utility company, uses heat. Instead of running at body temperature, the firm’s process first stews the excrement at 40°C for several days. It then transfers the fermenting liquid to a tank that is five degrees cooler. This two-tank system produces more methane than conventional methods because different strains of bacteria, which chew up different components of faeces, work better at different temperatures. The result of giving diverse groups of bugs a chance to operate in their ideal environments is, according to Mohammed Saddiq, GENeco’s boss, about 30% more methane from a given amount of excrement. In Germany a team at the Fraunhofer Institute in Stuttgart, led by Walter Trösch, is using a different approach. Dr Trösch has reduced the amount of time it takes to digest sewage from two weeks to one, by employing a pumped mixing system. This works faster than traditional methods for two reasons. The first is that stirring the sludge causes methane to bubble to the surface faster. From the bacterial point of view, methane is just as much of a waste product as faeces are from the human viewpoint. Encouraging this poison to escape allows the bacteria to survive longer and thus produce yet more methane. The second reason is that mixing the sludge moves bacteria away from chunks that they have been digesting and on to ‘fresher’ material that has not had as much bacterial contact. The result is a quicker digestion of the whole. The Fraunhofer pump system, which has already been deployed in 20 sewage plants in Brazil, Germany and Portugal, needs to operate for only a few hours a day, so does not require a large amount of energy. Sadly, that is not true of the approach used by researchers at the Tema Institute in Linkoping University, Sweden. They are developing a technique that employs ultrasound, rather than pumps, to break up the sludge. This increases methane yields by 13% but, at the moment, the process of generating the ultrasound consumes more energy than it yields.”


Historically, communities have treated sewage to prevent the spread of disease and to recapture increasingly precious water resources. Simply making the treatment plants energy self-sufficient would be a boon to communities. Generating excess power that can be sold is an extra bonus, like fudge frosting on a chocolate cake. The article concludes:


The consequence of techniques such as these is that an ever-larger proportion of sewage is being used as a raw material for energy generation. Germans already process about 60% of their faeces this way, and the Czechs, Britons and Dutch are close behind. GENeco reckons the figure in Britain by the end of 2010 will have leapt to 75%—enough, when converted into electricity, to power 350,000 homes. And the latest thinking is to improve yields still further by cutting out the middle man. Faeces are food that has been processed by the human digestive system to extract as much useful energy as possible. An awful lot of waste food, though, never enters anyone’s mouth in the first place, and this is an even more promising source of biogas. In America in particular numerous sewage plants have begun processing undigested food in large quantities over the course of 2009. This is the result of a collaborative policy by the country’s Environmental Protection Agency and its Department of Energy, to encourage the recycling of waste food in this way. In Britain, alas, public policy actually discourages such activity. Waste-water facilities there must pasteurise food scraps before they are processed, according to Michael Chesshire, the head of technology at BiogenGreenfinch, a company that modifies sewage digesters to use food scraps. That is a serious waste of brass.”


Methane produced by animals, like cattle, contributes significant amounts of methane into the atmosphere. In a future post, I’ll talk about the challenges farmers have dealing with animal waste. Capturing and using the methane produced by human byproducts to generate cleaner power is a good idea. Since we know that as long as humans eat they will do the “number two,” it’s about time we got over our sensitivities about how we dispose of fecal material. People will feel a little better about themselves if they understand they are part of the renewable energy sector. I already feel flushed with pride.

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