Electricity + Control September 2019

ENERGY MANAGEMENT + ENVIRONMENTAL ENGINEERING

of US$80.9 million in fuel costs) and avoid 274 110 tonnes of CO 2 emissions. One of the motivations for the project was the fact that Essakane’s transition to processing harder ore resulted in energy consumption at the mine increasing from about 14 GWh/month in 2013 to 26 GWh/month in 2015. Commenting on the installation at the time of the launch, Fabienne Demol, Executive Vice President – Global Head of Business Development at Total Eren, said: “This project demonstrates the benefits of integrating renewable energy in the mining industry. We are looking to replicate this type of hybridisation, especially in Africa where mines cannot always rely on the national grid. Renewable energy coupled with either storage or thermal- based power generation represents a truly viable option for industrial consumers since it enables competitive, reliable and clean power supply.” Otjikoto in Namibia The second major solar project to be completed last year was a 7 MW solar ‘farm’ or plant at B2Gold’s Otjikoto gold mine in Namibia. One of only two gold mines in the country (and by far the bigger), Otjikoto produced approximately 167 000 ounces in 2018. Otjikoto is what is known as an ‘island energy producer’ – meaning that it is off the Namibian national grid. Although the mine is not in a particularly remote area, the decision was taken during the development phase to install an on-site thermal power station when it became evident that relying on a grid connection would have delayed the start-up of operations. The thermal plant has a generating capacity of 23.5 MW provided primarily by four Cat medium-speed HFO generators. The solar plant complements the conventional generating capacity on site at Otjikoto with the integration beingmanaged by Caterpillar’sMicrogrid Master Controller (MMC). The MMC not only regulates the energy being fed to the HFO plant but allows for the seamless selection of the mine’s two energy sources (HFO or solar), choosing the most economically viable option at any point in time. The contract for the solar plant was awarded to Barloworld Namibia, in partnership with

The Otjikoto solar ‘farm’ comprises 62 400 thin-film solar panels. (photo: B2Gold).

Barloworld Power in South Africa, the Caterpillar dealer in Southern Africa, and Caterpillar Microgrid Solutions in the US. The project was completed at a cost of approximately N$115 million, on schedule and within budget. The installation was inaugurated at the end of May 2018 by Namibia’s Minister of Mines & Energy, Tom Alweendo. The solar farm comprises 62 400, 115-W Cat- branded thin-film solar panels, manufactured by its joint venture partner First Solar, Inc, which has its headquarters in Arizona. The panels are mounted on a PiA single-axis tracking system. The dc power is converted to ac power through Sunny tri-power three-phase SMA string inverters and is then distributed to the HFO plant via Schneider switchgear in the PV control building through a 3.5 km overhead powerline. B2Gold reported earlier this year that the solar plant is now providing approximately 13% of the electricity consumed on site. According to the company, changing the power plant to an HFO/solar hybrid facility reduced Otjikoto's HFO consumption in 2018 by approximately 2.4 million litres and associated power generation fuel costs by approximately 10%. Syama in Mali With the Essakane and Otjikoto plants now up and running, the next hybrid plant to come on stream will be at Resolute Mining’s Syama mine in Mali. ASX-listed Resolute announced in November last year the signing of a Joint Development

Electricity + Control

SEPTEMBER 2019

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