South Africa is blessed to have sufficient wave resources to support electricity generation using wave technologies as a viable platform. By harnessing the energy from waves using sophisticated technology Enerlogy will build an initial ‘wave farm’ of 10MW off the coast of South Africa. Initial steps will be to do a feasibility study based on data from test sites and assessment of wave resources.
Waves are generated by the wind as it blows across the sea surface. Energy is transferred from the wind to the waves. Wave energy is sometimes confused with tidal energy, which is quite different.
Waves travel vast distances across oceans at great speed. The longer and stronger the wind blows over the sea surface, the higher, longer, faster and more powerful the sea is. The energy within a wave is proportional to the square of the wave height, so a two-meter high wave has four times the power of a one-meter high wave. (equation p=h2)
Why Wave Energy?
Wave energy has the potential to be one of the most environmentally benign forms of electricity generation. It is a clean and renewable energy source and its potential is huge. Some additional benefits of wave energy are:
With the wave energy resource distributed across the globe, wave energy offers many countries the benefit of security of supply
Waves are generated over large areas of ocean and, once generated; travel immense distances with only small energy losses.
Waves can be anticipated one or two days in advance through direct satellite measurements and meteorological forecasts which provide a high level of predictability and hence good network planning.
Good seasonal load-following for regions where electricity demand peaks in winter given heating and lighting requirements (e.g. Northern Europe, Western Canada and North-West USA).
Although wave energy is a concentrated source of wind energy, as it has often traveled very large distances it is regularly out of phase with the local wind conditions. Wave energy can therefore help to balance output variability from other renewable sources and maximise the efficient use of electricity networks
Waves effectively average out the wind that generates them over large areas which results in a high level of consistency compared to wind or solar. Only on very few days per year are waves too weak to generate electricity.
As wave energy is, to varying intensities, found all across the World’s oceans, the market for electricity from wave energy is equally significant in both scale and distribution.
The World Energy Council has conservatively estimated the market potential for wave energy to be in excess of 2,000TWh/year. This is broadly equivalent to the existing deployed markets for nuclear and hydroelectric power. The fuel source for wave projects is free; therefore regions with the strongest wave resource will offer the lowest cost of energy from this renewable resource.
These regions are generally found in the temperate zones (30-60 degrees latitude north and south of the equator) where strong storms occur regularly and include Western Europe, North America, South America, South Africa and Australasia.
As wave energy is a new, emerging technology, which has yet to benefit from cost reductions through volume manufacturing and engineering refinement, it initially requires levels of additional market support in order to make it competitive against established sources of electricity which have already been supported through this phase of development.
There are already a number of countries and Governments around the world which have recognised the significant opportunities which come from wave energy and have put in place specific market support for early projects, including the UK, Portugal and Spain.
In parallel with a growing build-out of wave projects the costs of energy from waves will fall, which will mean that additional subsidies can be reduced. Lower costs for electricity coming from waves will also mean that wave becomes competitive in regions of the oceans which have lower energy levels.
The wave energy around the British Isles is equivalent to three times current UK electricity demand.
Moreover, it is technically possible to convert a sizeable fraction of this wave energy to electricity – the technically and economically recoverable resource has been estimated to be 50-90TWh of electricity per year, or 14-26% of current UK demand.
The UK is not alone. The western seaboard of Europe, facing the Atlantic, offers an enormous number of potential sites off the coast of Ireland, France, Spain, Portugal and Norway. The Pacific coastlines of North and South America, Southern Africa, Australia and New Zealand are also highly energetic.
The World Energy Council has conservatively estimated the market potential for wave energy to be in excess of 2,000TWh/year. In fact, any area with yearly averages of over 15kW per metre (shown on the global resource map) has the potential to generate wave energy at competitive prices.
Note that this threshold excludes areas such as the Mediterranean Sea and the Great Lakes of Northern America – despite their not-infrequent storms.
Global resource map
Global ocean energy resources are vast, and ocean energy technology clearly represents the largest untapped business potential within the renewables sector. The map below indicates areas where wave energy potential is greatest. There is a strong correlation between surface and surge energy. Commercial market for ocean energy taking off despite the limitations of current solutions
The map indicates areas where wave energy potential is greatest.
Market development for ocean energy equipment has to date been driven by pre-commercial pilots and markets for wave energy are still fairly limited. However it is evident that in the next few years the market will surge when successful technologies move from the pilot phase to commercialization.
Key drivers for renewable energy demand:
• Common public concern about global warming and pollution
• Uncertainty regarding sustainability of fossil fuel supply
• Global political agreements and combined actions to reduce carbon emissions
• Controversy over nuclear power
• Energy independence and security issues and volatility in oil prices
• Government incentives for technology development and energy generation from renewable sources with at least 48 countries having a renewable energy promotion policy.
• Increased focus and R&D investments from industry heavyweight, such as General Electric, Chevron and Shell.
• Enabling technologies nearing commercial viability .
• Existing public infrastructure for testing and prototyping ocean energy technology