A major challenge of wave water power is dealing with the intermittent (potential) nature of the power being produced. We may not need the power when the waves are moving, and when we do need it, the waves may not be there. Or we may want to save the energy generated at a time when power is cheap and sell it at a later time when power is expensive. In these cases it is desirable to store energy from waves.
Batteries store energy by electrochemical reactions. Battery technology has advanced rapidly in recent years. Newer technologies, such as lithium ion, have high energy densities meaning they can store more energy in a given size. The life expectancy as determined by the number of cycles by which batteries can be charged and discharged before losing their effectiveness has also increased substantially. However, the cost of advanced batteries is very high.
Older technologies such as lead/acid or nickel/cadmium are also options, but their lower cost has to be weighed against their lower energy densities and shorter life expectancies.
Pumped storage is an option for many wave energy systems built as hydroelectric facilities. When the electricity from the wave energy power is not needed in the electrical system, it is used to pump water into the reservoir. When the wave power is not available (or electricity costs are more attractive), the water can be released from the reservoir through the hydroelectric generator to produce electricity.
The “Smart Grid” would help in integrating the intermittent (potential) power from wave power into the electrical system. The concept is a computerized electrical distribution system that has the ability to control the demand on the electrical system as well as the supply. For example, it could route excess power from wave power to idle, parked electric cars that are connected to charging stations. Alternately, when there is a temporary shortage on the system, the same cars could supply a short-term boost.