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Electrifying the future

Our reliance on electricity means that we expect it to be available on demand. At the same time we want to cut greenhouse gas emissions drastically. Electrifying the future is about unlocking the third generation of wind power and living the future today with smart grids.

In 2013, the global installed capacity for offshore wind was around 6.5 GW, almost all of this built on bottom fixed foundations. Many coastal areas of the world the waters are too deep for this technology. Floating wind turbine technology offers a new opportunity to provide clean energy to countries and coastal regions with deep water coastlines. Floating wind turbines can be deployed in deep to ultra-deep waters, in the 1,000 metres range and beyond.

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offshore wind turbines

Demonstrating the technology

New floating wind turbine concepts are being developed and demonstration projects provide the first steps towards small generating arrays comprising a handful of turbines. 

This in turn will spark further research and innovation, and provide insight into how to combine technologies and further optimise designs. 

Reservoir water injection 

Demonstration projects are essential for the success of a future, prosperous, floating wind technology industry. However, power production from floating wind turbine technology could prove to be commercially viable for certain markets and applications already today.

Integrating the power supply from floating wind turbines with offshore oil and gas activities could provide an innovative mean to enable for example reservoir water flooding operations. 

A high-level economic assessment based on key technical components have indicated that a using a floating wind turbine to power a water injection system, could be an economically viable alternative at step-out distances of between 20-30 kilometres. 

This autonomous system is deemed as technically feasible and could reduce costs for developing marginal, satellite fields which today requires long power cables from the platforms. By avoiding gas turbines for powering the operations, also fuel costs can be reduced. 

A successful demonstration could have a significant impact for both the O & G and floating wind turbine industry.

Floating offshore reservoir injection
Floating offshore reservoir injection
Floating offshore wind turbines

Cost compression

Once the feasibility of floating wind turbine technology has been proven, the focus will shift to reducing costs and scaling up the size of installations. New technologies and improved manufacturing and installation processes will reduce costs.

Levelised cost of energy

Cost of floating wind turbine technology will to a large extent depend on the cost development of fixed offshore wind. Lean manufacturing of substructures, development of turbines, blades and station-keeping systems are major elements of future cost reductions for floating offshore wind turbines.

Rated power and rotor size

The trend is towards increases in turbine rated power and rotor size, leading to higher energy yield and improvement in LCOE. Turbines installed offshore in 2013 had an average size of 4 MW and demonstration projects for floating wind turbine systems currently under development are applying turbine sizes of 6-7 MW.

DNV GL believes that the turbine size is bound to increase in the coming decades. Some developers have that 10 MW offshore turbines, with a hub height of 130 metres and a rotor diameter of 200m, will be commercially available in the early 2020s. For 2030-2050, the average size could grow to sizes of 10-15 MW and up to 20 MW for new installations in the later part of the period.

Substructures, station keeping and anchoring

The number of developers and substructure concepts is constantly growing. Even though alternative designs are suggested, the industry is currently dominated by the three key design philosophies: SPAR, Semi-Submersibles and Tension Leg Platforms (TLPs), all well-known from the offshore oil & gas industry.

Future systems will be a correlated to developments in turbine design, the introduction of new materials like polyester, graphene and carbon fibre for mooring lines and tendon systems. Going towards increasingly deeper waters and larger arrays is likely to lead to new innovative mooring and anchoring solutions.

Operation and maintenance

Drivers for reduced O&M costs: 

- Increased turbine size 

- Fewer rotating parts 

- Optimised blade design 

- Improved accessibility 

- Remote monitoring and control 

- Remote robotised inspections 

floating offshore shipyard
A floating offshore shipyard
Levelised costs of energy graph
Levelised costs of energy are anticipated to drop between approximately 10-14 per cent for every doubling of installed capacity
Floating offshore turbine diagram
Growth in size of wind turbines since 1980 and future prospects; source EWEA
Floating offshore wind turbine connection graphic
A graphic showing connections between floating offshore turbines
offshore wind turbines

Large-scale power production

Combining floating wind turbines with energy storage, other renewable energy sources and implementation of smart grids makes it possible for countries to fully rely on renewable energy sources. 

Wind turbines provide bulk power production to meet the community's basic electricity needs. Solar panels generate power during peak demand hours when power-hungry systems like air-conditioning are most used. 

Flexibility 

Crucial for the integration of large quantities of intermittent uncontrolled power generating resources resides within the ability of the electricity grid to seamlessly absorb fluctuations. Energy storage can create flexibility, like pumped hydro, compressed air, and batteries. For offshore power generation an alternative concept can be to store pressurised water on the seabed by an energy membrane. 

The environment 

DNV GL and the offshore wind sector are working together with the fishing industry to integrate offshore wind, aquaculture, and sustainable fishing practices. Experience from other deep sea installations suggests that large steel structures could actually function as artificial reefs. New marine ecosystems promote numbers and diversity of fish populations. Industrial-scale trawling will not be possible in the vicinity of wind farms and more sustainable fixed-gear methods can be used instead. Floating wind turbines can form the basis for sustainable management of marine life and power production. 

Connecting offshore power to onshore grids 

Turbine rated power and offshore wind park size increase, requiring transmission of large volumes of electricity. HVDC is mainly used for point-to-point power transmission. Voltage sources converters in multi-terminal HVDC grids make it possible to feed-in power from different offshore wind farms into one HVDC supply cable.

Floating offshore gasson watertank
A floating offshore Gasson watertank
Floating offshore environment
Floating offshore connection
Connecting offshore power to onshore grids

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