Operating any form of ICT in remote locations offers considerable challenges beyond using the equipment itself. One of the key problems to overcome is being able to access a reliable source of electricity. This week News Update looks at two solutions to this problem. Rebecca Meyer and Will Cawood describe a biogas generator at a school in South Africa. Although now connected to the national grid it continues to use its own electricity to power a telecentre. Global Catalyst Foundation's Jeff Schneidermann describes two different responses in Tanzania: a biogas generator for a teachers' college and solar panels for a refugee camp.

SOUTH AFRICAN HIGH SCHOOL TURNS WASTE INTO POWER

Sixteen thousand rural schools in South Africa lack electricity, placing a large barrier to the universal introduction of computer science courses in the curriculum. Two thirds of rural schools lack adequate sanitation, and some 12% have no toilets at all, forcing students and teachers to use pit-latrines that pollute the ground water. These problems, seemingly unrelated, affect thousands of students and their hopes of some day joining the labor force of the information economy.

Solar Engineering Services (SES) of South Africa, one of the country's leading innovators in the application of renewable energy for the benefit of rural communities, came up with an ingenious way to address both the lack of sanitation and the lack of electricity. SES initiated a demonstration project in the use of biogas digesters at Myeka High School, showing that the digesters could be used to improve sanitation and provide fuel for electricity and other uses by converting human waste into useable energy.

The project took place at Myeka High School in Maphephetheni, a 2600-household community in KwaZulu-Natal Province, and was funded by the Department of Minerals and Energy (DME) of South Africa and USAID, via Winrock International. Myeka High School has about 1000 students and 30 teachers.

The biogas installation at Myeka uses human and animal wastes to produce gas for cooking, science experiments, and driving an electricity generator at the high school. The installation consists of two 20,000-liter digesters receiving the waste from 16 flushable school toilets, which are arranged in two concentric circles around the digesters (shown above). The installation also incorporates two cow dung inlet ports to increase the output from the digesters, and to cover weekends and holidays when the students are not in school. The main process that takes place in the digester is called anaerobic digestion. Anaerobic digestion is a biological process that occurs naturally in the absence of air. The process produces a gas principally composed of methane (CH4) and carbon dioxide (CO2), otherwise known as biogas. Biogas is typically 55% to 75% pure methane. To operate efficiently, biogas digesters need to be located where there are warm temperatures (35° to 40° Celsius in the digester) and water resources in addition to animal wastes.

The installation at Myeka High School has the capacity to deliver an estimated 13 cubic meters of gas daily, enough to produce 18kWh per day for computers and lighting. The biogas can be used as fuel for a 3kW modified diesel generator, which runs on a mixture of 20% diesel and 80% biogas. The diesel is used mainly to start up and lubricate the engine. To prepare the diesel generator to accept biogas as a fuel only one modification is required: the creation of a connection into the air intake tube for the biogas to flow through. Biogas from cow dung is considered better for fueling generators than biogas from human waste, because the latter's higher acid content causes corrosion of the generator parts.

Since the school was finally connected to the electricity grid about 6 months ago, plans have been made to use the electricity from the biogas-fed generator to power a public telecentre. Electricity from the grid costs the high school R0.35/kWh (US$0.05), so the provision of 18kWh/day of electricity from the biogas-powered generator could potentially reduce the planned telecentre's operating costs by up to R139 per month (USUSD20.70).

SES is working with the school and the Department of Agriculture on plans to fully optimize the use of the biogas digesters through additional activities, such as the abovementioned public telecentre, and the use of the effluent from the digester to fertilize fruit trees and grow reed beds. The effluent can be used in its raw state for above ground crops such as bananas, mangoes, litchis, and umdoni fruit, all of which are either indigenous or grow extremely well in the Maphephetheni region. It is hoped that the reed beds will serve a dual purpose, clearing pathogens from the digester output slurry so that it can be used to water ground crops, and producing dried reeds that can be sold to local organizations for making baskets and other products.

Myeka's biogas installation was planned and built by SES with strong participation from the high school's Biogas, Agriculture and Toilet Committee (BATCOM). Labour and material costs of the installation amounted to approximately R97,400 (USD14,504). This is equivalent to the cost of extending the electricity grid less than 2km, whereas the school was more than 5km from the nearest grid at the time the biogas installation was constructed. Comparative costs for a solar photovoltaic (PV) system, a diesel generator and a biogas digester are presented in Table 1 below. Total life-cycle costs (TLCC), annualised life-cycled costs (ALCC) and levelised energy costs (LEC) were calculated on the basis of a 20 year life-cycle and a daily load of 7.5kWh. The results show that biogas has the lowest LEC of the three off-grid options at R3.41/kWh (US$0.51), compared to R5.00 (USD0.75) for PV and R7.16 (USD1.07) for diesel:

Maintenance of the biogas digesters is low in cost. One of the biggest maintenance problems at Myeka has been caused by mischevous students, who will break the school toilet cisterns ­ and anything else they can get their hands on ­ just for fun. Still, the digesters have been relatively safe from attempts at theft, as opposed to the solar panels donated to the high school several years ago. As put by Will Cawood, one of the authors of this article, 'There's not much to steal in a human waste biodigester.'

For the rest of this story, go to: balancingact-africa.com