The economic cost of building hydroelectric dams is exorbitant. Not only a large sum of money is involved, but it displaces many riparian communities. The dam affects the ecology of the surrounding area and alters the natural course of the river. Water released from the dam into the river can be too low in temperature and poor in oxygen content, which makes the environment unfavorable for the river's wildlife.
Solar energy is harnessed by the use of photovoltaic cells placed over a large area. It requires special infrastructural development that can be expensive. The solar energy is limited to daytime and is controlled by the geography of the place. Places too far away from the equator do not get enough sunlight; similarly, cloudy or rainy days are bad for solar energy production.
Wind energy is reliant on strong wind that is dependent on uncontrollable factors like the geography of a place. Wind turbines are large and unattractive. They are noisy to operate and can be a potential threat to the wild bird population in the vicinity.
Geothermal energy production relies on the heat emanating from the earth's bowels. It is site-specific and not easily available at all places. The research and drilling for geothermal reservoirs is both time-consuming and expensive. The drilling for geothermal energy can sometimes bring up toxic chemicals and gases that are harmful to humans and the environment.
Biomass is organic matter like cow dung, straw, wood, poultry litter and food waste. Biomass can be converted to produce natural oil, gas or ethanol and used as fuel. Burning biomass for energy production produces greenhouse gases and particulate matter that is harmful to the environment. To make oil and gas from biomass using bioconversion techniques, biomass has to be accumulated in large containers called digesters. Digesters occupy a big space and are expensive.
Tidal energy is harnessed from the power of changing tides. Huge dams have to be built across a bay or an estuary. The dams are expensive to built and impact ecosystems due to the changing currents and water levels. Tidal barriers increase the amount of suspended matter in the water.