By HP van Huyssteen, project manager at Energas Technologies.
That southern Africa is becoming a key player in the international trend towards the development of renewable energy sources is no overstatement. A joint report by REN21 and UNIDO finds that renewables now account for 23,5% of the region’s generation capacity. SADC countries aim to increase renewable energy contribution to electricity supply to 27% by 2020 and 29% by 2030.
Regardless of the looming tide of renewables in southern Africa, I believe there is a huge untapped natural gas energy potential in the region. Responsible utilisation of this ancient fuel may help reduce the acute energy deficit faced by southern African counties.
Considering the damaging environmental effects caused by the burning of fossil fuels, natural gas may be one of the most appropriate transitional fuels in the drive towards a truly renewable energy landscape. Natural gas is the cleanest burning fossil fuel and releases up to 50% less carbon dioxide (CO₂) than coal, when used for power generation.
Wide implementation of renewable power is encouraging, but its susceptibility to environmental conditions means that it must be supplemented by a reliable and versatile source of power, such as natural gas. The absence of large-scale gas infrastructure in the region is in itself a hindrance to further development. If gas availability across the region was more widespread, the demand for it would certainly have been higher.
One way to get the ball rolling is to build anchor “gas-to-power” projects that can justify the necessary infrastructure developments, which will in turn promote further expansion. It is promising that the energy policymakers of the region, last year, at the SADC Ministers meeting held in Sandton, strongly endorsed natural gas as part of the energy mix.
Relooking the energy mix
Coal is still the backbone of power generation in the region, thanks to its abundance and low cost. However, increasing environmental and climate change concerns may preclude this energy source in the not too distant future. Access to electricity in southern Africa may be as low as 42%, according to the SADC Energy Monitor 2016, which further reports that biomass usage – such as burning wood and charcoal – accounts for more than 45% of the total regional energy consumption.
Rural communities are strikingly dependent on burning wood for heat and cooking. Natural gas, particularly liquefied natural gas (LNG), may be particularly a far better means of supplying these remote communities with electricity and heat (distributed on-site generation). LNG is easy to transport by rail, road or sea and can be used as an electricity feedstock in such cases. Electricity or heat from gas is available on demand and it can be started and stopped far easier than wood or coal fires.
Gas-to-power installations can be small enough to make economic sense for small communities, and are easily scalable when demand grows. One of the strategic benefits of natural gas is that it is a multi-use energy source and can be used for cooking, electricity generation, heating and even cooling.
Globally coal has been largely displaced by gas-generated electricity to reduce CO₂ emissions. Reinforcing this trend is the fact that gas-fired power plants typically take less than half the time to construct than coal-fired plants. I am positive that the discovery of large gas deposits in the northern parts of Mozambique (Rovuma basin) lends itself to further development in the region. Angola, the region’s largest oil producer flares almost 50% of its gas due to a lack of infrastructure to distribute the gas. The flared gas can be used to generate electricity.
Gas-fuelled power stations do not have to be that large. There is a new trend promoting micro-grids where power is developed in small communities where gas or biofuel is available. There is no need for expensive power lines which substantially delays the supply of electricity to smaller communities.
Biogas is increasingly used to generate electricity. Sources of biogas are municipal waste, sugarcane leaves, manure, agricultural waste, plant material and others. Engines or generator sets in the range from 100 to 500 kW are ideally suited and are available as complete skid-mounted factory-tested units, which means that site installations are relatively simple. Depending on the remoteness of the installation, micro-turbines can fulfil a similar function with far longer service intervals. However, overall efficiencies are lower than that achieved by reciprocating gas engines.
Combined heat and power (CHP) systems – which comprise a gas engine, generator and exhaust heat recovery system – are ideally suited to installations that have an electricity and thermal demand, such as hotels, schools, office blocks and retail centres. CHP development has come a long way and overall efficiencies may exceed 90%. This is certainly attractive when compared with a 38% efficiency of a conventional coal-fired power plant. Finally, natural gas, due to the ability to generate on a small scale, can free users from their dependence on the centralised electricity supply network.