Invasive plants to generate electricity in South Africa

GRAHAMSTOWN, South Africa, April 19 -- The small student town of Grahamstown in South Africa's Eastern Cape may soon be home to that country's first biomass power station fueled exclusively by invasive alien vegetation.

The deal between the local Makana Municipality and international environmental finance company Nollen Group will provide an estimated 150 jobs to local residents and help reduce alien vegetation in the area.

The power station, which is expected to cost R70 million ($10 million), is slated to be built alongside Grahamstown’s decommissioned coal power station. It could be completed by 2012.

“We chose the Makana region due to the high concentration of invasive trees and the amount of labour available in the area,” said Charlie Cox, a senior investment associated at Nollen Group.

Cox said the need for electricity in the area, as well as support from Makana Municipality influenced the choice of location.

Award-winning entrepreneur and biotechnologist Garth Cambray is the founder and director of Makana Meadery, a mead manufacturing company which currently occupies part of the old power station.

The biomass plant will produce three megawatts of power an hour, Cambray said. Grahamstown consumes between five and 18 megawatts per hour.

“(This project) uses a waste resource and turns it into jobs and income for the local community," Cambray said.

Alternative sources of energy are especially important in South Africa, as national power utility Eskom has been unable to supply the demands of the growing nation.

Eskom predicted in the late 1990s that it would be unable to meet the country’s electricity needs by 2007, yet their requests to construct more power stations were denied by the South African government until recently.

They have since begun construction on additional power stations, expected to be completed by 2015.
The country has been subjected to black outs since 2008, as Eskom periodically cuts electricity supply to certain areas (often without prior warning) to reduce the strain on the power grid.

Grahamstown is home to an estimated 140 000 people and relies on distant Eskom coal-powered stations in northern South Africa for its electricity.

One of the town’s main energy consumers is Rhodes University, which plans to increase student numbers by more than 6 percent in the next two years, increasing the demand for electricity.

The biomass power station would guarantee enough power to supply Rhodes and St Andrews, a large local high school, entirely, Cambray said.

Right now, coal provides more than 90 percent of the country’s electricity.

Experts say invasive alien vegetation such as black wattle, eucalyptus, pine, oak and Australian gum trees are environmental hazards in the water-scarce region.The plants grow very rapidly, consume vast quantities of water, destroy indigenous vegetation and change the ph level of the soil, making it difficult for other plants to grow.

Cultivated soil found on farms is especially prone to alien vegetation, which is expensive and difficult to remove. Even after the plants are cleared, the land needs to be treated regularly to avoid regrowth.

"Sometimes it’s cheaper for farmers to sell their farm and buy another one without alien vegetation than to clear their farm," Cambray said.

Cox estimates that more than 3,000 tons of plant material will be needed each month to fuel the power station. The steam released when burning the plant material will be used to drive turbines which in turn generate electricity.

Conservation Support Services, a geographical information specialists group, conducted a survey of invasive alien vegetation in a 70km (44 miles) radius around Grahamstown for Nollen Group.

Ben Codding, director of the group, said that their findings indicate the area contains enough invasive plants to sustain the power station.

“There are about 6,400 hectares of condensed invasive alien plant cover in the study area,” Codding said. “We estimate that there is between 400,000 and 1.2 million tons of available biomass.”

Because of the high concentration and growth rates of these plants, the power station will have a reliable supply of fuel.

Not all of this plant material will be suitable for the Nollen Group’s purposes, Codding said. Some smaller plants may have too little biomass to justify their removal, or could be located at a great distance from the road network or on a steep slope, which will make removal and transportation of the plants difficult.

Cox said his group intends to provide the first round of treatment to the land after removing the plants. Successive treatments will be the responsibility of the land owners.