Weighing the trade-offs of harnessing ocean power depends on the environmental value system in play. Each individual and group maintains a particular world view or paradigm through which it perceives and evaluates environmental issues.
water for energy
Water indirectly enables power generation by cooling power plants that use heat to make steam that drives a steam turbine. These thermoelectric facilities make up about 75% of the world’s power plants.
Thermal pollution standards limit the maximum temperature allowable for water returned to water bodies from a power plant's cooling system. When heat waves increase the temperature of incoming water, power plant operators sometimes decrease production to avoid exceeding their thermal pollution threshold.
Though hydroelectric power is attractive for many reasons, its reliability dwindles during droughts as needs such as drinking and irrigation compete for that water. The implications range from increased electric rates to grid strain to a lack of water for other uses.
Renewable electricity technologies such as wind turbines and solar photovoltaic (PV) panels do not use heat to make electricity, so they do not need cooling water. However, heat-based forms of renewable power such as concentrating solar power use water for cooling.
Water is used at various stages of the life cycle of fuel production and consumption. These stages include production, upgrade, transport, and end use.
Energy improves water quality through water and wastewater treatment, but energy can also degrade water quality through mistakes, accidents, or systemwide effects.
Water is used to transport energy to market in a variety of ways: by river barge or ocean ship, or even by pipeline.
Overall, about 15% of the world’s water is for producing or using energy in one form or another. While hydroelectric dams appear on the landscape as an obvious use of water for energy, other parts of the energy supply chain also rely on water for a variety of purposes.
Hydroelectric facilities leverage the sun’s energy, which lifts water to great heights through evaporation, and the force of gravity as the water travels back to sea level.
Global winds drive continuous waves with a force that beachgoers would easily recognize as powerful and unstoppable. The total resource is large and global, but expensive to harness.