Electricity + Control January 2019

ENERGY MANAGEMENT + ENVIRONMENTAL ENGINEERING

Pace-setting solar farm inaugurated at Otjikoto

Photograph by B2Gold.

One of the most innovative solar energy installations yet seen in a mining appli- cation is now operational at the Otjikoto gold mine of B2Gold in Namibia. T he Otjikoto Solar Farm, as the installation is known, will reduce the mine’s dependence on its existing heavy fuel oil (HFO) power plant and has already delivered savings of several hundred thousand litres of HFO since being com- missioned in early March 2018. Otjikoto is by no means the first mine in Afri- ca to commission a photovoltaic (PV) solar power system but it is probably the first to have a fully autonomous installation which can manage the combined thermal and solar resources available to the mine largely without human intervention. With a capacity of 7 MW, the Otjikoto Solar Farm is also one of the biggest installations of its type in Na- mibia and indeed in sub-Saharan Africa. An open-pit operation, Otjikoto is located in the Otjozondjupa Region of Namibia, approximately 300 km north of Windhoek and just off the na- tional highway linking the towns of Otjiwarongo and Otavi. Officially opened in mid-2015 (although it achieved its first gold pour in late 2014), it has been one the most successful gold mine start-ups seen in Africa in recent years. In 2017 it produced a record 191 530 ounces at a remarkably low cash operating cost of US$468/oz. It forms the back- bone of Namibia’s gold-mining industry, the only other gold operation in the country being the much smaller Navachab mine. Otjikoto is what is known as ‘island energy pro- ducer’ – meaning that it is off the Namibian national

grid. Although not in a particularly remote area, it is powered by a thermal plant which was installed during the development phase of the mine when it became evident that relying on a grid connection would have delayed the start-up of operations. The plant has a generating capacity of 23,5 MW – which is almost twice themine’s average demand – provid- ed through four Cat MaK 12CM32 medium-speed HFO generators, capable of generating a combined 19 MW, and three Cat 3516 high-speed diesel en- gines, with a total capacity of 4,5 MW. The plant has performed extremely well, delivering a 99,8 % power output availability since commissioning. Outlining the rationale for the solar farm pro- ject, Roos says that tight control of energy costs was essential for a low-cost producer such as Ot- jikoto, given that electricity generation has typical- ly accounted for approximately 12% of the mine’s overall operating costs and 35 % of total process- ing costs. “Going the solar route will allow us to achieve a very significant reduction in our con- sumption of HFO – which is steadily increasing in price – with the saving amounting to approximate- ly three million litres a year,” he states. “Moreover, it fits in well with B2Gold’s com- mitment to environmental stewardship. It will, of course, reduce the mine’s carbon footprint and the likelihood is that it will remain as an income-gen- erating asset long after the mine has closed, ben- efitting both local communities and the wider Na- mibian economy.” The Otjikoto solar project was approved by B2Gold Corporate in October 2016 after intensive feasibility studies. Subsequent to the approval be- ing received, a rigorous vendor evaluation process was initiated with the assistance of B2Gold Na- mibia’s appointed engineer, GS Feinsinger & Asso- ciates, a consulting engineering practice based in

Take Note! With a capacity of 7 MW, the Otjikoto Solar farm is one of the biggest in- stallations of its type in sub-Saharan Africa. The Cat ® Microgrid tech- nology is relatively newon the market and B2Gold is likely the first company in the world to deploy it in a mining application.

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28 Electricity + Control

JANUARY 2019