To prevent the intermittent shutdown of turbines and power-generating machines as damage control measures against aquatic weeds finding their way into the hydropower plant head pond, the Volta River Authority (VRA) in collaboration with the Ghana Maritime Authority (GMA) has embarked on an initiative to eliminate all aquatic weeds on the Volta River.
The exercise, which is targetted at the stretch between Kpong and Akuse of the Volta River in the Eastern Region, has been identified as very critical to reducing mechanical damage, high cost of operation, occasional reduction in the capacity of power generated, and socio-economic impact on the nearby communities.
Technical Manager at the Kpong Generation Station, Ing Korsi MacCarthy, mentioned that usually during August to November every year there is excessive growth of aquatic weeds on the river, which find their way into blocking the trash racks which stop them from entering into the machines. This reduces the pressure level of water supply to the machines for generating power, causing a shutdown of the machines.
“When these weeds submerge and block the trash racks we have, it reduces the flow of water into machines and pressure levels then reduce. At this point, depending on the volume of weeds that gets submerged, power generation can reduce from 40 megawatts per machine to as low as 15 megawatts or 20 megawatts. When it gets to 15 megawatts, we have no choice but to shut down and bring in cranes to clear the space at a high cost,” he said.
He added that in a situation when the weed gets into the machine, the machine is shut down for some weeks until the weeds get rotten and flow out of the machine before it can be powered-up again. This has affected power generating activities heavily in the past, he mentioned.
Director of Environment and Sustainability, Ing. Benjamin Sackey, added that the skimmers secured from the GMA will serve as critical installments on site to harvest all aquatic weeds on the river whenever and wherever they grow to stop them affecting the authority’s operations.
He commended the GMA for such a timely intervention to secure regular power supply from a hydroelectric source for the nation.
The VRA has deployed three weed-harvesters known as ‘skimmers’ from the Ghana Maritime Authority (GMA) to support VRA’s efforts in controlling the menace of aquatic weeds on the Volta River.
Director of Inspections and Survey-GMA, Captain William Thompson, mentioned that the collaboration between the two institutions is a formidable one that will help clear all the weeds, reduce the operation cost on VRA and cuts in power supply due to shut down of plants, and also serve as a good source of fishing water for the local communities as they have done over the years.
He indicated that two of the machines will be on the Kpong head pond and the other side at the Ada stretch to clear all aquatic weeds on the Volta River, for it to better serve the people and also support aquatic life.
Past efforts to address aquatic weeds
Since the appearance of aquatic weeds on the Volta River, VRA has implemented several actions to ensure their management and control. These steps include mechanical control, chemical control, biological control and manual weed-harvesting.
Two transport barges and two weed-harvesters were handed to VRA by the Environmental Protection Agency (EPA) in 2012 as the first in a series of support to help with weed-harvesting on the Kpong head pond.
However, the EPA’s weed-harvesters have reached the end of their useful lives and been decommissioned, hence the need to acquire skimmers to take over for more effective management of the situation.