Thursday, 13 May
Massai protesting against Olkaria Geothermal Plant Expansion
South African Times reported yesterday of Massai tribesmen blocking the drilling of four geothermal wells in Kenya's Rift Valley region to protest environmental and health damage. According to the news article, around 100 protesters stopped engineers from KENGEN, the country's electricity generation firm, from working on the wells near the town of Naivasha. "We have for many years suffered under KENGEN and this time we shall not allow the drilling of more wells near our homes," Natata Kisotu, the protest leader said. They complained about the toxic fumes coming out of the wells, the noise from the steam gushing out, and the contamination of surface water that their cattle drink. The KENGEN Project manager Geoffrey Muchemi said the locals would be relocated and explained that an environmental assessment had been done and approved by a government regulatory body and the World Bank which is financing the project.
The existing literature suggests due diligence had been followed in previous developments in the Olkaria field. Readers of this blog may remember a previous posting about this field. In that posting I concentrated on the technical issues. A quick search after reading the Times article ended up with several references on environmental management in Olkaria fields.
The existing Olkaria III is a binary plant with the condensers being cooled by wet cooling towers. The geothermal fluid is being reinjected to minimise water pollution. A paper from KENGEN presented at the Reykjavik International Geothermal Conference in September 2003 reports on comprehensive environmental management practices. The geothermal fluid contains H2S with concentrations in the steam plume coming out of the wells varying between 0.15 - 1.25 ppm. The Report also states that the H2S levels around the camp vary between 0.02 and 3.4 and 4.4 PPM at the power station. The measurement of 4.4 PPM near the power station is coming from the H2S released from the steam separator. These numbers are significant but appear to be well below the Kenyan maximum occupational exposure limit (reported as 10 PPM).
The purpose of this posting is not to pass judgment on the quality of environmental management at Olkaria nor on the validity of the Massai claims. I wanted to make the point that if the contribution geothermal energy increases in the future, the geothermal energy sector will have to deal with these environmental issues. All countries that have significant geothermal installed capacity have these issues, e.g. Iceland, New Zealand, California.
Concentrating on the noncondensables, it looks to me that there are two options to deal with nasty non-condensables: (a) scrub the emissions as in coal-fired power plants using FGD(Flue Gas Desulphurisation); or (b) send the gases back to the reservoir with the reinjected fluid. The former adds to the expense and may not work with all non-condensables. The second option requires the geothermal fluid to be circulated at a pressure high enough to keep the non-condensables in solution. Thinking further along these lines, higher pressures would be easier to handle in a binary plant using a supercritical cycle. In fact, it would probably make it easier to design such a plant if the brine-side pressure is similar to the cycle pressure. This is one more motivation for working towards supercritical cycles in geothermal binary power plants.
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