Energy Generation

In Europe, electricity is generated in many different ways. Electricity is currently not easy to store, so demand and generation have to be managed so that they are always in balance. Some example types of electricity generation currently in mass use are:

  • Burning chemical energy stored in fossil fuels such as coal and gas
  • Converting solar energy from the sun using photovoltaic cells
  • Converting the kinetic energy from the wind using a wind turbine
  • Using the heat created in the nuclear fission reaction
  • Using the kinetic and potential energy in water to drive hydro power plants
  • Burning chemical energy stored in biofuels

In Europe we currently face a ´trilemma´ of objectives for the energy we produce. The key goals are for energy generation to be:


Generation sources should be able to meet demand today, and in the future. They should also not cause irreversible damage to the environment through the emission of carbon and pollutants.


Generation should be affordable and not make electricity bills too expensive for the consumer.

Contribute to security of supply

Generation should be predictable and able to meet consumer demand. A variety of different generation types means that shortages in fuel supply are not as big a problem.

Renewable targets

  • Renewable generation is energy generation from a source that can be replenished, unlike finite resources such as fossil fuels.
  • Examples of renewable energy sources are the wind, the sun and the ocean waves and tides.
  • The EU’s climate and energy framework sets three key targets for the year 2030:
    • At least 40% cuts in greenhouse gas emissions (from 1990 levels).
    • At least 32% share for renewable energy
    • At least 32.5% improvement in energy efficiency
  • These targets are intended to reduce emissions and also to reduce dependence on generation from fossil fuels, creating a more diverse and sustainable energy mix.

Units of electricity

Electricity generation is measured in kilowatt-hours (kWh). This is the amount of power produced over a period of time. To give some perspective boiling a kettle uses around 0.1kWh. The average house in Europe uses around 4500kWh per year.

CO2 production

Carbon dioxide production is measured in megatonnes of carbon dioxide per year (MtCO2). 1kWh of coal generation produces 0.94kg of CO2 emissions. European targets are to cut greenhouse gas emissions by at least 40% on 1990 levels by 2030.

Social & environmental

  • The social and environmental impacts of electricity generation vary depending on the type and location of the power plant.
  • Negative social impacts include noise and visual disturbances due to power plants, positive social impacts include job creation and cheaper energy generation.
  • Environmental impacts include the production of greenhouse gas emissions and the impact on habitats of local wildlife.

What is Ocean Energy?

There are various ways that electricity can be generated from the ocean resource. Examples of this are wave, tidal stream, tidal lagoon, ocean thermal energy conversion and salinity gradient. This site focuses on wave and tidal stream as the two main forms of ocean energy with the highest resource in Europe. Wave and tidal stream are new types of electricity generation technologies that have large potential but are not yet producing large amounts of electricity


  • Sustainable source of electricity - doesn't require burning of fossil fuels
  • Varied energy resources contribute to security of supply - when the wind doesn't blow or the sun isn't shinning there is usually still wave and tidal energy
  • Wave and tidal resources are much more predictable than other forms of renewable generation
  • Less social impacts than other forms of generation - very little visual or noise pollution for those on land
  • Resource is sited close to fragile coastal communities, potential to provide jobs and revenues to such communities
  • Helps us meet European renewable energy targets
  • Helps meet European and worldwide carbon reduction targets
  • Ocean energy is highly abundant, and can provide 10% of Europe’s electricity mix by 2050
  • Using electricity from renewable sources provides independence from importing fossil fuels from other countries


  • Many forms, wave energy generation device types in particular have not converged to a single ideal solution like wind turbines have
  • The harsh sea environment results in increased maintenance costs - the saltwater and increased loads due to waves and tides result in more damage and corrosion to devices compared with other renewable generation
  • Very little knowledge of the environmental impacts and wave and tidal generation since there have been no long term deployments
  • Social impact considerations are different from power plants on land e.g. shipping and fishing lanes
  • Wave and tidal are still developing technologies, so they can be expensive to install and operate

Tidal Energy

There are two forms of tidal energy generation - tidal stream and tidal lagoon. This web page focuses on tidal stream.

The tides are caused by the gravitational pull of the moon as it orbits around the earth. The tide comes in and out approximately twice a day. A tidal stream moving fast enough for energy generation occurs at locations where water has to pass through a confined area, for example between two pieces of land or islands.

Tidal stream devices generate electricity by turning the kinetic energy caused by the tidal stream into electricity, usually by the turning of blades around a central axis in a tidal turbine.

Horizontal axis tidal stream turbine
  • This type of turbine generates electricity from the rotation of the blades around a horizontal axis when driven by the tidal stream water flow.
  • Most tidal stream generation has converged to this type of generator.
  • There are various forms of horizontal axis tidal stream devices, these include seabed mounted and floating turbines.
Vertical axis tidal stream turbine
  • This type of turbine generates electricity from the rotation of the blades around a vertical axis when driven by the tidal stream water flow.
Tidal kite
  • This type of tidal device is attached to the sea bed and 'flies' under water, catching the tidal stream with the main blade and turning a small horizontal axis turbine to generate electricity.

Wave Energy

Waves are caused by the movement of the wind on the surface of the ocean. Over long distances this effect can concentrate energy in large movements called ocean swells.

Wave energy is generated by converting the kinetic energy in the movement of the waves into electricity. This is done in many ways and there are multiple forms of wave energy converters. There is active research in novel devices for wave energy, with many options for solutions still to be investigated.

Point absorber
  • This type of WEC often has a buoy-like structure which floats on or near the water surface.
Oscillating wave surge converter
  • This type of WEC is anchored to the seabed and is mostly or fully submerged. It generates electricity from the flap movement due to wave surges.
Hinged attenuator
  • This type of WEC floats on the water surface. It generates electricity based on the movement of the structure segments relative to one another due to the movement of the waves.
Oscillating water column
  • This type of WEC is fixed in a partially submerged position, open to the sea water. Air is enclosed in the device, which compresses and expands as the waves move and generates electricity.
Rotating mass
  • This type of WEC is a floating, unbalanced device. The movement due to the waves causes the unbalanced weight inside to move and generate electricity.


For further learning download our handout or play the game to see if you can use this information to power a set of islands!


The educational materials featured in these web pages have been created through the ETIP Ocean project, in collaboration with the EnFait and Marinet2 projects.