Harvesting Sweet Energy from Africa's Sugar Industry

Terri Hathaway
Friday, December 1, 2006

Sugar is king in Mauritius, accounting for 90% of cropland, 25% of foreign exchange earnings, and supporting 1 in every 18 residents of this tiny island nation. But sugar is not the only export coming from the cane fields – electricity is a valuable byproduct of the harvest.For nearly 50 years, Mauritius has been using agricultural waste from its sugar industry to help electrify the nation. Not only does Mauritius have the highest electricity access rate in Africa – often cited at 100% – but more than a third of its electricity comes from power plants using bagasse, the fibrous waste from sugar cane. With 10 power plants in operation and even more planned, bagasse could provide over half of the country’s electricity by 2010.

“Bagasse energy development has enabled the country to displace its reliance on imported fossil fuel, diversify its energy base, and reduce electricity generation investments by the utility,” said Dr. Kassiap Deepchand, Technical Manager at the Mauritius Sugar Authority. “It has also improved the viability of the sugar industry by allowing its modernization and rehabilitation, enabled savings in foreign currency by decreasing fossil fuel imports, and reduced our greenhouse gas emissions.”

How it works

Cogeneration is the process of generating both electricity and heat simultaneously in a single power plant. By using agricultural waste – sugar is one of the most efficient – cogeneration uses a renewable source of biomass. The fibrous cane stalk can be burned to make steam and generate electricity. Sugar factories can easily meet their own energy requirements with bagasse and well-designed, efficient plants can generate a surplus for sale to the national grid or to support a mini-grid in rural locations.

Unless some of the bagasse is stored for use during the non-crop season, another fuel must be used to produce electricity year-round. A renewable energy fuel such as ethanol could be used; otherwise, a fossil fuel is used. In Mauritius, the power plants were designed to use all available bagasse during the crop season. Only three of the 10 bagasse plants run year round, using coal during the half of the year when bagasse is unavailable.

Keys to Mauritius' Success
Mauritius has some unique characteristics that may have helped influence its success with bagasse. The country does not have its own fossil fuel resources and relies heavily on imported fuel. The island was uninhabited before colonization. After periods of Dutch, French and British control, the country gained independence in 1968 and now has one of the highest GDPs per capita in Africa ($13,000). The country is home to just 1.2 million residents. Sugar cane, covering 40% of the island’s land, has benefited from preferential trade agreements with Europe, which have paid up to three times the world market price.

Interest in exploiting energy from bagasse began with just one sugar factory in 1957. In the 1980s, two bagasse cogeneration power plants were built and began to export power to the grid. In the 1990s, the combination of successful plants and increasing oil prices led to the development of a Bagasse Energy Development Programme, a collaborative effort between the government and the private sector.

For over a decade, government policy has continuously supported building a successful cogeneration energy system, not only integrating bagasse into the country’s energy planning, but prioritizing it. A clear policy on use of bagasse for electricity was developed, and supporting policies and legislation, such as removing income tax for bagasse electricity revenue, were put in place. Targets for growth were set. Barriers to meeting those targets were identified and addressed along the way.

Small cane growers have not been ignored. A Sugar Investment Trust, comprised of small growers and industry workers, was established in 1994 and owns a 20% stake in all of the cane milling companies, 20% in the seasonal bagasse plants, and 14% in the year-round plants. The shareholders are then entitled to a dividend based on the profits of the trust. About a third of the nation's bagasse energy comes from small growers.

Mauritius' sugar industry does, however, face risks. Sugar production costs are on the rise, and global prices are projected to drop by about a third in the next few years. But Deepchand doesn’t see this as a risk. “The drop in sugar prices offers an opportunity to mitigate the impact on revenue by enhancing electricity export to the grid,” he said, predicting that mill centralization and technological upgrades will make the bagasse plants more efficient.  

African Expansion
Researchers estimate that there is great potential for bagasse cogeneration in many African countries. Total cane production in Africa is 90 million tons, representing 10,000 GWh of potential bagasse-generated electricity. Sudan has possibly the highest potential, with approximately 644 GWh (just greater than Mauritius’s 600 GWh potential); Kenya has 530 GWh; Ethiopia, 150 GWh; Uganda, 173 GWh; and Tanzania 101 GWh of potential.

While it is believed that many African countries could produce bagasse-based electricity, commercial viability requires an estimated 200-300 tons of cane to be crushed per hour, which is far more than many countries currently produce. It also requires careful management of a country’s sugar industry, something often neglected by many African governments.

Deepchand believes that creating an enabling environment for independent power producers to build cogeneration power plants is a key step to successful bagasse generation elsewhere in Africa. "The success achieved in Mauritius can be replicated in the region, the African continent," he says with confidence.