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What is offshore renewable energy?


Offshore renewable energy is the name given to electricity which is generated using ocean-based resources. Captured out at sea (via wind, wave or tidal or thermal energy), offshore renewable energy is  transformed into electricity using modern technology and supplied back into the power network back onshore. Offshore renewable energy offers a cleaner, more sustainable alternative to traditional fossil fuels. Given the natural abundance of wind, waves and tides, renewables offer a viable way of supplying large amounts of ‘green’ energy. As such, offshore renewable energy is a key element of the green transition, holding great potential for addressing climate change and better protecting the natural environment going forward.


What are offshore renewables? 


There are four main types of offshore renewable energy – wind, wave, tidal and thermal, each at a different stage of development and with its own unique challenges and opportunities.


Wind power is generated via turbines which use blades to collect kinetic energy from the wind as it blows. This process has been described as working in the opposite way to a fan: the wind causes the turbine blades to spin. These blades are connected to a drive shaft so when they spin, they turn an electric generator. The generator produces power which is then sent to a substation. Here, the electricity is collected and changed to a higher voltage using a transformer before being sent onshore for consumer use.


As you may have guessed from the name, wave energy generates electricity using the power of ocean waves. The bigger, faster, and longer a wave, the more power it is able to generate. By placing specialist equipment on the surface of the ocean, it is possible to capture the kinetic energy produced by the periodic up and down movement of the sea. This energy is used to turn a turbine, which is attached to a generator, in order to create electricity that can then be transported back onshore.


As with wind and wave energy, tidal energy is also generated using turbines, however in this instance, the turbines are located beneath the ocean’s surface. Underwater turbines are installed out at sea in areas known to have high tidal movements. The movement of the water turns the turbine blades, which in turn drive a generator that produces electricity. The power produced is then sent back onshore via power cables, ready for distribution.


Thermal energy typically refers to power generated using either the Sun (solar power) or the Earth’s interior (geothermal energy uses heat deep within the Earth to create steam that in turn generates electricity). There are a variety of technologies, such as heat pumps, PVT panels, flat-plate collectors and solar water heating, which can be used to harvest this thermal energy and convert it into electricity. More recently, we have also seen the emergence of a new type of thermal energy: Renewable natural gas (RNG). RNG is essentially methane which is captured during the decomposition of organic matter at farms, landfills and wastewater treatment plants. The gas is then cleaned and distributed via the same infrastructure and processes as those used for existing natural gas production.


Is offshore renewable energy better?


Offshore renewable energy offers a range of advantages over both non-renewable energy sources and onshore renewable energy sources. When compared with onshore renewables projects, offshore renewables projects offer a number of advantages, including:

  • Taking up less real estate
  • Having little to no visual impact on local populations
  • Eliminating concerns about noise pollution for the general population
  • Avoiding the need for new long-distance transmission lines as they can be located close to load centres
  • Generating more power (in the case of wind farms) as offshore wind turbines can be larger, plus the wind out at sea is faster and stronger, meaning more energy is collected.


Likewise, offshore renewable energy offers a number of advantages over non-renewable energy production, including:

  • Having a comparatively minimal impact on ocean ecosystems
  • Being more sustainable as it relies on abundant natural resources which will never run out, unlike fossil fuels
  • Delivering cheaper, more cost-effective power production than fossil fuels, enabling electricity bills to reduce
  • Contributing towards the green transition by offering a ‘greener’ alternative  that helps to reduce carbon emissions, move towards net zero targets, and mitigate climate change.


What are offshore support vessels?


An offshore support vessel (OSV) is a type of ship that has been specially designed to carry out a specific function out at sea. While different types of offshore support vessels have different purposes, all OSVs share the same common aim of ensuring smooth and efficient operational processes for offshore projects. Offshore support vessels are usually purpose-built to suit a project’s specific operational needs, making them very versatile. They have a range of functions in offshore renewables projects, such as:


  • Anchor handling
  • Building and repairing offshore equipment
  • Overcoming construction challenges
  • Platform support
  • Safety inspections of platforms, wells, pipelines etc
  • Transporting equipment and the required structural components for a project
  • Underwater maintenance.


Some of the main types of OSVs include:


  • Accommodation Ship
  • Anchor Handling Tug Vessel
  • Cable-lay vessel
  • Construction Support Vessel
  • Diving Support Vessel
  • Inspection, Maintenance, and Repair Vessel
  • Platform Supply Vessel
  • ROV Support Vessel
  • Seismic survey ship
  • Well Intervention Vessel.


Offshore support vessels are essential for the smooth running of offshore projects. In short – no OSVs means no offshore renewables project. Therefore, the availability of OSVs has a huge impact on the number, type and speed of the projects which can be completed.