Potential Benefits of Offshore Wind Farms Extend Beyond Clean Power Generation

This is another installment in our series of stories highlighting new technologies and initiatives that can combat climate change, mitigate its effects, or assist communities in adapting to a rapidly changing world.

Coastal wind turbines are an environmentally friendly source of electricity that perform exceptionally well in regions with strong ocean breezes. Although offshore wind farms are more expensive to construct than their onshore counterparts, they have the potential to undertake additional tasks that would increase their value.

Canadian researchers have proposed a hydrogen (H2) production facility as a valuable addition to wind farms. Each H2 molecule consists of two hydrogen atoms bonded together, and the sole byproduct of burning or converting H2 into electricity is water. However, because H2 rarely occurs naturally, it must be manufactured using typically dirty processes. The cleanest approach to H2 production is employing energy from wind or solar sources, which is known as green hydrogen.

Explaining the Hydrogen Rainbow

According to mechanical engineer Haris Ishaq, hydrogen “is a clean-burning fuel that can carry and store energy. Green hydrogen has the potential to solve many of today’s problems.” Researchers in Canada are not the first to propose using offshore wind farms to generate green hydrogen. Another team investigated this concept last year. Ishaq’s group has gone a step further and suggested incorporating a third function into wind farms, namely, direct air capture (DAC) of CO2 from the atmosphere.

DAC has received significant attention as a means to combat climate change. The Canadian team described the benefits of wind farms fulfilling these three roles in a study published in the International Journal of Hydrogen Energy on July 16.

Atmospheric carbon dioxide levels have been rising rapidly since 1950 and are currently higher than at any point during the past 400,000 years. Direct air capture (DAC) is capable of extracting CO2 from the atmosphere. The gas can be stored, effectively enabling net-zero greenhouse gas emissions by 2050. The US government is investing millions of dollars in two major DAC projects, including one in partnership with Climeworks. Click on the image to zoom in.Luthi, D., et al., 2008; Etheridge, D.M. et al., 2010; Vostok ice core data/J.R. Petit et al., NOAA Mauna Loa CO2 record.

Utilizing Wind and Water Resources

Canada possesses the world’s longest coastline, stretching an impressive 243,042 kilometers (or 151,019 miles) thanks to its mainland and numerous islands. The majority of this coastline lies along the Arctic Ocean, but over 27,000 kilometers (or 16,800 miles) border the Pacific Ocean. Canada has already constructed many wind farms along its Pacific coast, taking advantage of the consistent, powerful breezes in this region. Furthermore, offshore wind farms face less competition for space at sea compared to their onshore counterparts.

However, there are downsides to offshore wind power. According to wind energy researcher Michiel Zaaijer from Delft University of Technology in the Netherlands, “Offshore wind farms tend to cost two to three times more than onshore wind farms.” This additional expense is due to the heavier equipment required for offshore wind farms, which must be able to withstand strong winds, large waves, and powerful currents. Additionally, the cost of sending personnel to install, operate, and repair offshore equipment is high. Zaaijer, who was part of the team that proposed integrating green hydrogen production into offshore wind farms, suggests that using the surrounding water to generate an alternative energy source can offset these costs.

An electrolyzer is a device that splits water into hydrogen (H2) and oxygen. To achieve this, the electrolyzer necessitates fresh water, not salt water. In order to remove the salt from seawater, Ishaq’s team has proposed employing reverse osmosis, a process that uses an electric pump to push seawater through a salt-filtering membrane.

The hydrogen produced by the electrolyzer can then be used as a raw material for ammonia production, a vital component of fertilizers and fuels. Alternatively, the H2 can be transported via pipelines to onshore storage facilities. When needed, the chemical energy in the hydrogen can be converted into clean electricity for the power grid using gas turbines. This is particularly important when wind and solar generation cannot meet the required power levels. Essentially, the combination of electricity generation and multi-purpose hydrogen production can enhance the value proposition of offshore wind farms.

Powering Carbon Capture Technology

For the second additional task of offshore wind farms, capturing carbon dioxide (CO2) from the atmosphere, the researchers turn to existing direct air capture (DAC) systems. One of the companies specializing in DAC technology is Swiss firm Climeworks.

DAC devices resemble large vacuum cleaners and require electricity to operate. Fans draw air across a solid material that absorbs CO2 while allowing other gases, predominantly nitrogen and oxygen, to pass through. Once the solid material is saturated with CO2, the fans stop running and the device closes.

Explaining Carbon Dioxide

The next step in the process involves applying heat to the solid material. Once it reaches a temperature of 100°C (or 212°F), the material releases the stored CO2. The same solid material can then be reused to capture additional CO2. According to Ishaq, one of the major challenges the team faced was finding a way to provide the necessary heat for this process. The electricity generated by wind turbines can be used to power the DAC device’s fans as well as an electric boiler or heat pump for heating the solid material. However, the new study proposes a third option: storing a portion of the hydrogen produced by the electrolyzer and burning it later to generate heat. To store the released CO2, Ishaq’s team suggests injecting it into basalt, a type of deep-sea rock. This rock reacts with the CO2 and converts it into new rock within 10 to 25 years.

Swiss company Climeworks has developed a process for capturing CO2 from the air. This technology, which is utilized at a facility in Iceland, could potentially be deployed at offshore wind farms. The process employs a solid material to capture CO2 molecules, and the captured CO2 can later be injected into underground rock formations where it solidifies.

What’s on the Horizon?

This new study is part of a broader project known as Solid Carbon. In other components of this

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