The addition of a 35 MWp solar photovoltaic (PV) plant and 17 MW/15 MWh of energy storage to the existing 64 MW thermal engine plant was decided. This new energy mix is anticipated to save over 13 million litres of fuel, reduce carbon emissions by 39,000 t/y, and generate a payback in just over four years.
Integrated hybrid energy solution
In the context of the Fekola mine, which is an off-grid electrical island, the battery is performing a lot of different services simultaneously, including frequency response, voltage support, shifting solar energy, and providing spinning reserves. The energy load is very flat, with a steady consumption rate around 40 MW as the mining equipment is operating consistently, 24/7. However, if an engine trips offline and fails, the battery serves as an emergency backstop. The controls reserve enough battery energy capacity to fill the power gap for the time it takes to get another engine started, and the software inside each inverter enables the battery to respond instantaneously to any frequency deviation.
The reciprocating engines operate most efficiently at 85-90% of their capacity: this is their 'sweet spot'. But if there is a sudden spike in demand, if a little more power is needed, or if mining equipment is coming online, then another engine needs to be run to meet the extra load.
With the battery providing spinning reserves, the engines can be kept running at their sweet spot, reducing the overall cost per kilowatt hour. Moreover, with the solar plant providing power during the day, three to four engines can be shut down over this period, providing a quiet time to carry out preventive maintenance. This really helps the maintenance cycle, ensuring that the engines operate in a more efficient manner.
See the whole article on International Mining here: https://im-mining.com/2021/01/18/optimising-energy-management-b2golds-fekola-mine/
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