Rivers are continuously recharged in water cycle. Because of the force of gravity, water flows from high points to low points. There is energy (kinetic) contained in the flowing water. The amount of available energy depends from the volume of streamflow and the change in elevation (or fall) from one point to another. Hydroelectric power (hydropower) plants convert the kinetic energy in flowing water into electric energy.
In order to generate electricity, the water has to move with sufficient speed and volume to turn a device called a turbine, which in turn rotates a generator to generate electricity. Approximately, ten liters of water per second falling ten meters can generate one kilowatt of electricity which could power some 5 LCD TV sets.
Today, using the energy of moving water (hydropower), to generate electricity is the largest source of emissions-free, renewable electricity worldwide. The first Liberian hydroelectric power plant opened on the Farmington River near Haberl-Firestone in 1942. The plant was constructed in order to supply power to a United States military airport at Roberts-field.
The largest Liberian hydropower station was built, some 30 km from Monrovia, on the St. Paul River in 1967. The Mount Coffee plant had a maximum generating capacity of 64 MW. During the First Liberian Civil War the power plant was damaged and the power generation stopped. The rehabilitation project of the Mount Coffee hydroelectric plant started in 2012. The project is co-financed by the Government of Norway, Government of Germany, European Investment Bank, U.S. Government and Government of Liberia. The modernized power plant will have four turbines units with 22 megawatts each. The new Mount Coffee hydropower plant is expected to be completed by the end of 2016.
The NVE Project founded a feasibility study of small hydropower on the Kaiha River in the Lofa County. The power plant will be part of the mini hybrid grid with combination of hydropower, solar PV and diesel generation, and the grid will serve Foya-Kolahun-Voinjama area. The construction of this project is expected to start in 2016/2017.