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Pamenus Tuso
TO most Bulawayo residents, the mere mention of Ngozi Mine evokes images of heaps of smelly garbage and scores of flies hovering over the vicinity.

But to environmentalists, Ngozi Mine, a common reference to a Bulawayo City Council rubbish dump site, is a potential source of energy which if exploited fully can be a panacea not only to the city’s power shortages but to the country’s as well.

Zimbabwe is relying on uneconomical and unsustainable power imports from neighbouring countries.

An assortment of rubbish dumped at the “mine”, located on the outskirts of the city, which has become a haven of waste harvesters, could easily solve the city’s energy crunch for good if the powers that be are willing and committed.

In Sweden, more than 99 percent of all household waste is recycled in one way or the other, turning it into gas, heat or any other raw materials.

Other developed countries are already harnessing methane gas from landfills and converting it to useful energy rather than letting it escape into the atmosphere where it becomes a greenhouse gas harmful to the ozone layer.

Renewable energy expert and principal energy development officer in the Ministry of Energy and Power Development, Mr Blessing Jonga, said there is huge potential for municipalities to utilise biodegradable waste to produce energy.

Mr Jonga said local authorities in Zimbabwe can sustainably generate energy in two areas namely: waste water treatment at sewage treatment plants and vegetable markets and landfills.

“Big cities and towns have sewerage treatment plants that treat sewer from residential and industrial areas. Most of this waste is organic. At sewage treatment plants in cities like Harare and Bulawayo, there are digesters which help in treating organic waste through decomposition of these organic materials by methane producing bacteria. Biogas, which is a gas composed mainly of methane, carbon dioxide and hydrogen sulphide and traces of other gases is produced in these digesters during fermentation,” explained Mr Jonga.

Through this process, Mr Jonga said biogas for domestic use such as cooking and lighting can be harnessed through pipes. He, however, stressed that the methane gas must be contained because of its adverse effects of high global warming if allowed to escape into the atmosphere.

The biogas can also be used to generate electricity using biogas generators which are called combined heat and power systems.

Small towns and growth points can also install digesters and use their sewerage stabilisation ponds to produce biogas that can be used for power generation.

The expert also concurred with environmentalists that municipalities were failing to utilise their dumpsites to generate power for the benefit of residents.

“There is potential to convert all dump sites in cities and towns to proper landfills in order to produce methane for power generation. This process requires waste separation first. Inorganic materials should go for recycling while the organic waste goes to well-lined landfills so as to avoid environmental hazards such as fires and water pollution,” said Mr Jonga.

In principle, the BCC is one of the few municipalities in the country which has embraced the concept of renewable energy.

“The Bulawayo City Council has allowed for funding under the Bulawayo Water and Sewerage Services Improvement Project (BWSSIP) for feasibility studies to be carried out to determine the scope of the bio-gas generation and the resultant areas of usage, be it electricity generation or industrial and domestic heating. It is only after the feasibility studies have been concluded that a concrete decision shall be taken to either invest in the technology or not,” said BCC senior public relations officer Mrs Nesisa Mpofu.

She said the BCC is also engaging strategic partners on the importance of investment in the sector.

All biogas generated at the city’s sewerage treatment plants, Mrs Mpofu said, is released into the atmosphere as there is no infrastructure in place to harness the gas for sustainable use.

The City of Harare has also made significant inroads in generating electricity through bio gas from vegetable waste. At the moment, the council is constructing an 800m3 biogas digester system at Mbare Musika near Matapi Flats.

The digester will be fed by vegetable waste from the market place, sewer from the flats as well as organic food waste from surrounding restaurants and houses. The biogas produced will be used to generate electricity.

Besides harnessing energy and bio-slurry (organic fertiliser) council officials say this project will save the local authority money for transporting organic waste to Pomona dumping site.

The Ministry of Energy and Power Development, under the Rural Electrification Fund, has also constructed a 350m3 digester system at Kotwa Growth Point in the Mudzi area in Mashonaland East Province.

The construction of the three digester systems (50m3, 100m3, and 200m3) which are being run by the Kotwa Rural District Council was completed last year and the system is producing gas which is being used for cooking purposes by local restaurant owners.

The digesters are fed by sewer from Kotwa Township, kitchen food waste and vegetable remains from local restaurants and market places.

Mr Jonga said his Ministry will continue to promote clean energy technology as well as work with relative stakeholders like local authorities in this endeavour.

“There is now capacity in the country for biogas technology. Biogas digester technology is actually also a waste management technology which can be used to treat waste water,” said Mr Jonga.

Director of Emmaus International Mr Justice Zvaita said waste energy is relatively cheaper than other fossil fuels.

“Energy from waste is relatively cheap compared to other forms of power. As a way forward, both the government and private sector should develop capacities and skills in efficient and profitable waste treatment projects,” said Mr Zvaita.

Zimbabwe is currently facing a huge power deficit. The power shortage has caused serious inconveniences to domestic, commercial, industrial and farming consumers. Most companies have now resorted to expensive and unsustainable alternative power sources such as diesel power generation.

Power is critical to economic development and there is a positive correlation between reliable power supply and growth in gross domestic product