Bioenergy is arguably the most versatile of renewable energy sources. It is the only source that comes in solid, gaseous or liquid form and can provide power and heat as well as transport fuels. Bioenergy, unlike most other renewable energy sources, can be stored relatively easily and can, therefore, provide energy to dispatch as needed.
Biomass is a major indirect source of solar energy, with wood being the major source thereof globally, making up an estimated 87% thereof. The bulk of the world’s forests are natural forest, with reported natural forest area amounting to 93% of global forest area, or 3.7 billion ha, in 2015. In 2011 the annual wood removals amounted to 3.0 billion m3 globally, of which half were for woodfuel. There was a net loss of some 129 million ha of forest between 1990 and 2015, roughly the size of South Africa, representing an annual net loss rate of 0.13% [FAO, 2015a].
With this said, it is rather difficult to measure bio-energy as a whole, especially distributed uses for cooking and heating. Cumulative worldwide installed capacity at the end of 2016 was around 90GW and is anticipated to reach 130GW by the end of 2025. After showing a consistent growth rate for a decade of an average of 11% per annum some slow-down is taking place.
South Africa’s biomass industry has predominantly been dominated by the need to re-use waste in plants from the sugar and pulp industries. Recently a small number of biomass projects had been approved to produce power to the grid or biogas. Most of the biomass production is currently located in the north-eastern and eastern parts of the country. The main primary processing energy carriers in South Africa consist of wood residues from the forestry industry, maize residues from the agricultural industry, cane residues from the sugar industry, and manure and litter.
To replace coal consumption substantially, mainly maize residues and sugar cane residues are of interest. An estimated 32 million ton of coal per annum can be replaced by biomass or 16% of the current internal use. Additional interesting feedstock streams (<1 million ton/a) include black liquor from the paper and pulp industry, slaughterhouse waste, alien vegetation and residues from other agricultural products that are produced on smaller scale than maize, such as soybean, wheat and grain sorghum
Looking into the longer-term future development of the national bioenergy sector, it must be realised that increasing the country’s agricultural and forestry sector substantially is limited by water scarcity. The water situation in neighbouring South African Development Community (SADC) countries is quite different from South Africa. As a result the average forestation cover in SADC is 33%, compared to only 7% in South Africa. Despite this difference about 50% of existing forest plantation area is still in South Africa.
The potential for biomass cost reductions remains highly heterogeneous as a result of different stages of development of various technologies. Cost reduction potentials are relatively small for established technologies; however, the long-term potential for cost reductions for less mature technologies remains good.
Most of the biomass production is currently located in the north-eastern and eastern parts of the country per figure below.
Figure: Biomass potential in South Africa [DME, Eskom, CSIR, 2001]
Food and Agricultural Organisation of the United Nations (2015a) ‘Global forest resource assessment 2015’