If you have seen my blog before, or are looking at it now, (ahem, as you should be if you are reading this) you can see my previous posting about biogas and waste in a small-scale business model with a cartridge or small receptacle style collection paradigm. Here is a paper I recently wrote that expands on that, and can include a traditional sewer and solid waste treatment type, as well as normal waste with mechanical separation. It is brief, because of the necessity of the forum I was using, but here is the whole paper…
Africa and the World, an Energy and Agriculture necessity
Africa is on a cusp of a revolution in how it lives. What that revolution is will depend heavily on how it comes to fruition. Africa has many problems, and none will be solved quickly, but ideas are the currency of the future, and so, here is mine. There is a push for biodiesel produced and farmed in Africa, but destined to make profits, and be used, mostly in foreign markets. (http://www.guardian.co.uk/environment/2011/may/31/biofuel-plantations-africa-british-firms) Even the local governments push that the revenue will be mostly tax generated to improve the standards of living through social programs. (http://www.africabiofuel.com/Benefits.aspx) Yet the report on Africa’s problems concerning irrigation and mechanization show a distinct need for diesel-engined equipment to further the mechanization and agricultural development of Africa to maintain standards for the population, economies, and governments of Africa sustainably. I have another suggestion: poop. Or, more accurately, waste. Disposal of garbage, human, and livestock waste all have massive potential in a continent with the varied geography, natural resources, and cultures that Africa has. They all share problems common to the world however, which is to say that mechanization and progress almost inevitably lead to more waste.
Biogas generators have been around for awhile, but only in recent years have the efficiency and multi-use capabilities really been looked at, and developed. The most efficient design is a CHP (Combined Heat and Power) design that not only gets energy from the Methane produced, but uses the exhaust gasses to drive a steam turbine. And let us not forget that the exhaust from burning Methane is about 60% water (clean water) and 30% carbon dioxide, with a few impurities making up the remainder. (CHP and municipal solid waste designs here: http://www.clarke-energy.com/gas-type/sewage-gas/ and http://www.clarke-energy.com/gas-type/biogas/mbt-ad-energy/ best diagrammatics I found were from this companies’ website, but the principle is the same everywhere) the same principles and basic designs apply across a range of waste sources: the leftover material from fermentation, for alcohol or biodiesel production, the organic waste from agriculture including livestock waste and unused plant material, solid waste from landfill-type facilities, and my favorite, seaweed. One of the ideas not discussed in any website, but the technology is sound, is to use the exhaust gases from a methane burner to power desalination. Distillery methods of desalination are old, well-proven, and of extreme utility to the parched regions of Africa, and the Sea Salt leftover from the process is a valuable commercial commodity worldwide as well as locally. There is some concern for a major impurity known as siloxanes, which leave a silicate residue from the generation. This is also a commodity, as the silicate can be smelted same as with any silicates mined. Also, the sludge left after anaerobic digestion is a high quality fertilizer that enriches the soil, and slows or eliminates the erosion and strip-farming techniques used without high-quality fertilizers.
To recap, there is a renewable resource for electricity production, and it’s waste products are: heat, to be used for generating steam electricity, creating nearly 90% efficiency, or to be used to desalinate water for drinking or irrigation; its exhaust is mostly water vapor, again usable for drinking or irrigation; and carbon dioxide, a useful commodity itself for petroleum production, or even soft-drinks; and high quality organic fertilizers. The byproducts are almost completely usable, either for the direct good of the populace, or as commercially salable commodities. With village-based digesters, it can scale down for remote areas to produce their own intermittently, or with village size collectors, the waste can be transported to larger collection facilities to maximize constant running and efficiency and to make up for the extra transportation costs. Also, the by products of biodiesel production make excellent biogas seed materials. (http://www.clarke-energy.com/gas-type/biogas/agricultural-biogas/)
With a trinity of needs; mechanization, fertilization, and irrigation, driving the agriculture, and a solid electrical infrastructure to co-develop the industrial and commercial sectors along with that agricultural growth, waste is a serious resource for regions that are used to subsisting on less than human or direct livestock power, as well as industrialized regions transitioning to a more sustainable future. And as a bonus, all the wonderful fauna in Africa can help: think of all the electricity that can be made from elephant dung and other large animals. I focus on Africa for this, but the ideas can be implemented anywhere, from Africa, to Central America, to developed regions. San Diego, CA already has biogas electrical generation supplementing other municipal electricity sources, and is one of the largest users of desalinated water. Future designs for electricity could incorporate both. Central American, or Carribean nations with coastlines could benefit from this also. But Africa has the greatest potential gain, both in the short term, and in the long run. It is a sustainable energy source for now, and the future.
Other sources: http://www.sustainablebusiness.com/index.cfm/go/news.display/id/24176 , http://emispec.ca/en/internal-combustion-engine-powered-by-biogas.php , http://askville.amazon.com/combustion-byproducts-methane-natural-gas-Comparasons-ethanol-pump-help/AnswerViewer.do?requestId=2747357 , http://ga.water.usgs.gov/edu/drinkseawater.html , http://www.sciencedirect.com/science/article/pii/S0360544206003033 , http://www.biocycle.net/2012/12/biogas-production-and-potential-from-u-s-wastewater-treatment/ , http://cdn.intechopen.com/pdfs/17591/InTech-Biomass_waste_as_a_renewable_source_of_biogas_production_experiments.pdf