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Alien Energy: Unlocking the potential of invasive plants in South Africa


Invasive alien plants (IAPs) are a scourge across Southern Africa – with species like black wattle and port jackson found across the region. It is estimated that more than 10% of South Africa’s land mass is covered by IAPs to some degree and they use up to 6% of the country’s fresh water (which can potentially increase up to 16% without eradication measures[1]), with an increase rate of 5-10% every year in land coverage[2]. These species, plus the many other invasives becoming common in South Africa, have devastating impacts on waterways, local biodiversity and livelihoods. In the Western Cape of South Africa’s Cape Floral Region (where 70% of plants are found nowhere else on earth), it is estimated the two-thirds of sub-catchment areas are invaded by alien plants where they “alter soil ecology, increase the frequency and severity of wildfires and significantly impact river flow and aquifer recharge.”[3]

It is estimated that IAPs could supply 11.3 million tons of solid biomass annually in South Africa[4]. However, this biomass source is currently largely underutilised as a result of logistical limitations. After clearing, most of the IAP biomass is left on-site and therefore potential valuable opportunities to use IAP biomass are wasted.

The environmental and societal case for managing these invasive alien plants is clear. However, while these plants have value locally as firewood, animal feed and for construction, these uses have traditionally not provided sufficient incentive for large scale clearing.

With the urgent need for fossil alternatives in order to combat the climate crisis, sustainable biomass is becoming an increasingly important source of feedstock for fuels, energy and materials markets. This could be the answer to solving the prickly issue of invasives in South Africa – and beyond.

Invasives are not a managed crop – they grow wild across both private and public land. In South Africa, the removal of these plants is mandated by the government, but landowners and local municipalities often don’t have the funds for effective eradication and management programmes. Additionally, guidance for the responsible removal of these materials has not been developed.

To unlock the significant potential of invasive alien biomass to feed the biofuel and bioenergy markets, RSB has included guidance on its harvest within its new Standard Amendment for Woody Biomass. RSB requires that eradication of invasive alien plants is driven by government law or environmental mandate. By providing guidelines on identifying invasive alien plants, requirements for its harvest, and the necessary plans that must be in place to ensure land is rehabilitated and environmental gains maintained, RSB’s approach is designed to build market confidence in these plants as a feedstock source and support local and national eradication programmes.

While the removal and burning of IAPs immediately results in the release of carbon; long term carbon sequestration at levels linked with the type of land rehabilitation is expected.

The removal of IAPs has substantial positive impacts on biodiversity, water security and livelihoods. Proper removal of invasive alien plants is the first step to restoring native biodiversity and provide additional ecosystem services such as improved soil quality and reduced severity of wildfires.

Research shows how IAPs removal delivers a larger water yield than many alternative water supply options such as groundwater exploration, water reuse and desalinisation – at a fraction of the cost[5]. Labour intensive land clearing and transport is also estimated to create approximately 1 job per 7 hectares, an especially potent opportunity for social development in rural and disadvantaged segments of society with low employment rates.

This approach has been developed through close collaboration and engagement with stakeholders in South Africa and around the world, including WWF, the Fynbos Trust, the Western Cape Department of Agriculture and others. Two pilot studies were conducted in South Africa to test the applicability of the RSB IAP approach in practice, how it can be certified and define the types of evidence required for certification of sustainable Invasive Alien Plants for certification.

RSB participates in the South African Biomass Knowledge Sharing Platform – an initiative jointly led by the South African and Dutch governments aimed at stimulating long-term collaboration with South-African companies and organisations for mutual commercial benefit in the biomass sector using an integrated and sustainable approach.

The platform has been supporting the development of a research piece by the University of Utrecht titled “Bioenergy potential from invasive alien plants: Environmental and socio-economic impacts in Eastern Cape, South Africa” published in February 2022.

Finally, in partnership with local stakeholders including the South African Biomass Knowledge Sharing Platform and WWF South Africa and thanks to a programme funded by The Boeing Company, RSB is developing an incentive mechanism to link the positive social and environmental impacts of IAP eradication to markets over the course of the coming years.

[1] WWF South Africa, Water Facts and Futures Report,

[2] South Africa Department of Environment, Forestry and Fisheries:

[3] The Greater Cape Town Water Fund: Assessing the Return on Investment for Ecological Infrastructure Restoration, November 2018:

[4] Bioenergy potential from invasive alien plants: Environmental and socio-economic impacts in Eastern Cape, South Africa:

[5] The Greater Cape Town Water Fund: Assessing The Return On Investment For Ecological Infrastructure Restoration, November 2018:, pages 36, 37

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