Ocean energy

Vattenfall believes that ocean energy will be the next renewable technology to be commercialised within 10 to 15 years. Our concern for the climate and the environment is one of the main reasons for our focus on ocean energy.

Photo: A buoy connected to a wave energy converter.

The aim of the ocean energy programme is to meet the demands of our customers

As part of this focus we have initiated a Research and Development programme in ocean energy. The aim of Vattenfall’s Ocean energy programme is to meet the demands and expectations of our customers.

We also want to ensure that we are the benchmark of the industry when ocean energy reaches its commercial phase. Our goal is to own and operate commercially viable ocean energy farms.

Ocean energy is a renewable energy source, in which electricity can be generated from thermal differences, tidal streams, waves or differences in salinity. This means that the ‘fuel’ is inexhaustible and free. Moreover, the operation of ocean energy converters does not emit carbon dioxide or other greenhouse gases that contribute to global warming.

Our activities in the field of ocean energy support Vattenfall’s strategic direction of ‘making electricity clean’, and our goal of becoming a climate neutral company by 2050.

Read more about Wave power

Wave power – potentials and challenges 
Market conditions 
Development phases 
Wave power technologies

Wave power – potentials and challenges

Right now we are focusing on wave power. Wave power is an unexploited renewable energy source that has several attractive features:

• There is a huge global theoretical potential for energy from the waves, in the order of several thousands of TWh. Even if only a small part of wave potential can be exploited this will still mean potential of several hundreds of TWh. The total annual electricity consumption in Sweden is approximately 135 TWh.
• Waves have a longer duration than winds, and tend to shift in their incidence to a greater extent compared to winds. This means that electricity can be generated from the waves after winds have died out. It also means that wave power complements – rather than competes with – wind power.
• The environmental and visual impacts of offshore wave power farms are expected to be low.

Nonetheless, wave power is still an immature technology, and challenges lie ahead. The sea is a harsh environment and the demands on any successful wave power device will be severe. Devices must be able to survive the worst storms, and be able to function with a minimum of maintenance, since weather conditions will limit access. They also need to have an acceptable economic performance to be commercially viable.

Other challenges relate to infrastructure and regulatory issues. Promising locations for wave power are often in areas with a weak power distribution grid. This practical issue will need to be overcome before any large-scale introduction is feasible. Other areas to consider are the effects of wave power on the environment, and the permit application processes.

Since wave power is a new source of energy, little practical experience has been assessed concerning its impact on the environment, nor of the processes and level of detail involved in the granting of permits for wave energy farms.

Market conditions

The best conditions for wave energy are on exposed west coasts in the temperate zones. The temperature differences give rise to winds, which in turn produce waves that increase in height as they near the land. Relate this to Vattenfall’s core markets, the most interesting areas are Ireland, the UK (primarily Scotland) and Norway.

However, in the initial phase there is a need for market subsidies for wave energy, which the Irish and Scottish governments in particular have recognised. Therefore Ireland and Scotland are today interesting markets for Vattenfall.

Development phases

Vattenfall is presently in the first of three development phases. We are working predominantly with pilot tests, establishing sites, obtaining permits for wave power sites and broadening our expertise. This first phase is estimated to continue until 2011. The second phase will focus on developing and operating demonstration wave power farms. The demonstration units will be multiple wave energy converters, with an aggregate rating of 5 to 10 MW.

The second phase also includes securing permits for future commercial farms that will be in the range of 100 MW or larger. This phase is estimated to run between 2012 and 2018. The third phase is the commercial stage, involving the establishment of large-scale ocean energy farms. We expect wave power to become commercial at some time between 2019 and 2022.

Wave power technologies

Based on an evaluation of more than 15 different wave energy technologies, we have chosen to actively support two of them; Pelamis and Wavebob

Pelamis was the world’s first commercial scale machine to generate electricity to the grid from offshore wave energy. It is a semi-submerged construction composed of cylindrical sections linked by hinged joints. The wave induced motions of these joints Is resisted by hydraulic rams which pump high pressure oil through hydraulic motors that drive electric generators to produce electricity. Pelamis new P2- version consists of four sections with a total length of about 180 m, 4 m in diameter and has a rated power of 750 kW.

Wavebob consists of two floating bodies. By adjusting the water ballast of the submerged tank the two bodies can be made to heave out of phase. The relative motion between the bodies is used to absorb wave energy in the connection point between the bodies.

A full scale Wavebob will be around 20 m in diameter, with a 90 m vertical construction below surface and have a rated power of about 1,5 MW. The photo shows a 1:4 scale
model in Galway bay, Ireland.