Offshore Wind and Wave Energy Could Cut Grid Costs by 17% by 2050

Key Things to Know:

• Offshore wind and wave energy have significant potential along the US West Coast, with a combined energy generation capacity of 1.2 times the annual electricity demand for the Western Interconnection.
• Combining offshore wind and wave energy offers greater reliability and efficiency than using either technology alone, with fewer hours of no power output.
• Economic benefits include shared infrastructure and reduced costs due to economies of scale, potentially lowering the cost of energy by 2050.
• Grid impact modeling shows that deploying both technologies could reduce total installed capacity by 17% by 2050, helping achieve a zero-emissions grid.

Global power systems are changing, and many countries are changing their electrical grids from heavy fossil fuel power to a mixture of fossil fuels and distributed energy resources (DERs)—such as solar, wind, and other intermittent renewable technologies. The aim of this transition is to decarbonise the grid and reduce the carbon emissions produced. However, with so many DERs available and each energy and geological landscape being different from country to country, there is often a lot of debate about what the optimal mix of DER integration looks like. 

Researchers have recently undertaken a study at some of the lesser considered DERs in offshore wind farms and wave energy and how their integration could help grids to lower their emissions in the western interconnection of the US—with the aim of eventually producing zero emission grids. As mentioned above, each energy landscape is different, but the West Coast of the US has an abundance of shorelines that could be harnessed for offshore wind and wave energy. 

The Potential for Wave Energy and Offshore Wind on the US West Coast 

There is a lot of potential for both offshore wind and wave energy along the western coast of the US—i.e. California, Oregon and Washington. It’s estimated that the energy potential of offshore wind farms is 800 TWh/yr and 240 TWh/yr for wave energy. The potential energy generation combination of these two renewable technologies alone is around 1.2 times the annual electricity demand for the Western Interconnection. However, despite the potential for large energy generation and the reduction of local grid carbon footprints, there are currently no offshore wind turbines off the western coast—and there are only two commercial offshore wind farms (5 turbines and 12 turbine farms) off the eastern coast of the US. There are also no commercial wave energy farms off either coast. 

Both wave energy and offshore wind have their own advantages. Wave energy is predictable up to 3 days in advance, so is more reliable and consistent than many renewable energy systems. In the winter months, it’s thought that wave energy could have more availability than in the summer months, so it can be complimentary to other technologies (such as solar) which have their peak during the summer months.  

For offshore wind, one of the biggest driving factors for considering their use is that they have higher capacity factors than land-based wind turbines. From a social perspective, there’s also the fact that many people don’t like the sight of wind turbines on land as they can obstruct views over a landscape, but this is not an issue if they are offshore. Placing them offshore also reduces the noise and shadow casting that occurs with land turbines. 

Combining both offshore wind and wave energy technologies also offers benefits over installing just one of the technologies. Studies have previously shown that combining wave farms and offshore wind farms off the coast of California would lead to fewer than 100 hours with no power output per year. In comparison, it was deduced that offshore wind farms alone would have more than 1000 hours of no power and wave farms would have over 200 hours of no power if used alone. Combining the two technologies in an area means that costs for infrastructure, development, sub-structure, and transmission can also be shared. 

New Study Looks at the Impact of Wave Energy and Offshore Wind on the Grid 

While studies have been undertaken on wave and offshore wind energy, many of them don’t consider the wider impacts that these technologies could have on the grid once deployed. Researchers have now modelled offshore wind and wave energy as individual technologies with the potential of collocation in a power system capacity expansion model of the western interconnection with zero carbon emissions by 2050. 

The model used was a SWITCH model, which is a long-term capacity expansion model that has been used in other studies focusing on low to zero-emission electricity grids. The model used over 7000 candidate plants that could be built across 50 load zones of the Western Electricity Coordinating Council (WECC)—which are connected by 126 aggregated transmission lines. The model investigated investment and dispatch decisions to minimise the cost of meeting the load power demands of each zone. Decisions were made on the model up to the year 2050, which is the point in time when WECC-wide carbon emissions from electricity generation are expected to reach zero. 

The model captured a range of scenarios where there could be a simultaneous decrease in costs for offshore wind farms and wave energy, meaning that it’s beneficial to install them in the same location. The model also showed that if more offshore wind is installed over time, economics of scale would lower the barriers of entries for more offshore technologies and provide lower costs for offshore wind. The model showed that offshore wind and/or wave energy would become much cheaper by 2050, meaning that they could be used as cost-effective energy sources for driving the transition to low-to-zero carbon emission grids. 

Economic and Infrastructure Impacts of Offshore Wind and Wave Energy Deployment

The study showed that a full deployment of offshore wind and wave energy of the western interconnection could reduce the total installed capacity by 17% by 2050. There are still some trade-offs that might need to be done because while more offshore wind could reduce barriers to entry, the lower energy cost targets for wave power would see a reduction in transmission expansion, whereas the lower offshore wind targets would increase transmission expansion. 

The study concluded that if wave energy can reach a cost parity of land-based wind turbines by 2050, and the offshore wind energy aligns with the advanced offshore wind NREL 2022 ATB scenario, then both wave and offshore wind energy could reach to about 6% and 9% deployment to achieve cost-optimal zero-emissions in the western interconnection. 

Reference: 

Hidalgo-Gonzalez P. et al., Offshore wind and wave energy can reduce total installed capacity required in zero-emissions grids, Nature Communications, 15, (2024), 6826.