Conclusions and Future Prospects

Conclusions and Future Prospects

Chapter 11 CONCLUSIONS AND FUTURE PROSPECTS Wave energy utilization is a technology that is still at a very early stage of development. In certain n...

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Chapter 11


Wave energy utilization is a technology that is still at a very early stage of development. In certain niches of the market it is commercially competitive, such as in the supply of power for navigation buoys, in the wave-powered pumping of water for desalination plants, and in the generation of electricity for isolated coastal communities that currently depend on diesel generators. However, further innovation and technological development is required before the utilization of wave energy can be introduced on a large scale in the general energy market. It is a well known observation that, due to experience and improved methods of production, the unit cost of a product usually diminishes as the production volume increases. A typical trend is a reduction of 20 to 25 percent of the inflation-corrected price for each doubling of the cumulative production (Fischer 1974). For this reason, there are good hopes for the large-scale utilization of wave energy in the future, since the energy costs of the best present schemes are not excessively high compared to current market price (Falnes 1996). The cost reduction due to experience and innovation illustrates the handicap that new energy technologies face in market competition with well-established, conventional energy technologies. This observation should be borne in mind when comparisons are made between the energy costs of new technologies and the energy costs of conventional plants. As a human has to grow from conception to an adult person, so a new energy production method has to develop from an idea to mature technology. Using this analogy, we may perhaps say that wave energy is still in its infancy, wind energy is a teenager and conventional energy is an adult. In some wave energy research programs, e.g., United Kingdom in the 1980s, it was assumed as a design goal that the devices should convert as large a fraction as possible of the wave energy impinging on a coast line. However, since the natural energy in the ocean is "free", this is not necessarily the best strategy. Instead, the installed power capacity, relative to the available power in the sea, should, in the future, be left as an open parameter in the economical optimization of wave energy converters. While such a strategy may result in reduced Overall power production, it should achieve a higher duty factor and lead to better overall economic prospects. Also there will be less requirement for primary energy-storage capacity to even-out the effect of wave variability. To date, such considerations have not been the dominating strategy in the design o f the majority of wave 133

energy converters deployedin the ocean and along shorelines. Instead, rather simple technologies have been utilized, with many of the devices being essentially civil engineering structures that are probably too large to maximize the ratio between energy production and investment. To increase this ratio, more sophisticated designs are required. Wave-energy devices of a simple type may offer better economic prospects if constructed in non-industrialized countries where labour is inexpensive. For this reason, wave energy may become commercial earlier in such countries than in industrialized countries. Also, in progressing to more advanced technology it will be necessary to develop new components, e.g. electronic hardware and software, pumps, valves, turbines, pneumatic and hydraulic motors. Such advanced technology will likely require local expertise for the operation and maintenance of installed wave energy converters. A large offshore or near-shore wave energy plant can be envisaged as a collection of many (hundreds or thousands) primary wave-energy converting units, each with a power capacity in the range from 100 kW to 1 MW. Thus the production of such units will be serialized, which will reduce costs. Hydraulic or pneumatic energy can be collected from many such units and fed to a central unit containing a large turbine and electrical generator. This housing may be placed on the sea bed or, in the case of near-shore wave energy converters, on land.