HIGHLIGHTS
• A newly developed UC/ED model was used to evaluate how the theoretical use of offshore wind energy would affect the New England electric grid during a specific extreme cold snap and during the period from 1949 to 2018.
• Wholesale electricity pricing would have declined during the extreme cold snap if 4,000 megawatts of offshore wind power was available.
• Offshore wind power also would have reduced wholesale electricity pricing between 1949 and 2018 with the best reduction occurring during the winter compared to the summer. 

Wind energy capacity is continuing to grow as the efficiency of turbines is steadily increasing. The result has been the cost of wind energy is continuing to drop, which is becoming significant at this time because traditional petroleum power generation sources are becoming more expensive.

In a previous TLT article¹ published in 2021, wind energy accounted for 7% of total global electricity demand at that time. A study discussed in this article estimated that installed global wind energy capacity will expand from 282 gigawatts (GW) in 2013 to approximately 4,800 GW in 2050. This increase means wind energy’s share of global electricity supply is expected to rise to approximately 30%. The net result is that the global temperature increase by 2100 will decline by approximately 0.3 C, and the time when the critical threshold temperature increase of 1.5 C will be reached may potentially be extended by six years.

The prospect of utilizing wind energy as a sustainable source to reduce the negative consequences of climate change is a key driver. But wind energy also must demonstrate an economic benefit to also be attractive to utilities.

Wind power can be produced either using land-based or offshore wind turbines. Kerem Ziya Akdemir, graduate student in forestry and environmental resources at North Carolina State University in Raleigh, N.C., says, “Each of these approaches has their advantages and disadvantages. Land-based wind farms can be built at lower capital costs but can only be established in remote areas that are not near urban or suburban population centers. This may result in inconsistent power generation due to higher variability in wind speeds on land.”

Akdemir continues, “Offshore wind production is more expensive in not just constructing the turbines but also the undersea digging needed to place cables between wind farms and the power grid on land. But the main advantage is that wind speeds offshore are higher and much more consistent, which will lead to the greater use of wind power instead of more traditional options (such as natural gas, coal and oil-fired power plants) that may be more costly and will certainly generate higher levels of pollutants.”

Akdemir points out that offshore wind energy also can lead to higher operations and maintenance costs if there is a problem with a wind turbine. Wind turbines also need to be able to operate at wind speeds up to approximately 25 meters per second. Akdemir says, “Above this cut-out speed, wind turbine operation is too problematic, which is why rotor shafts are prevented from moving. But the prospects that wind turbines can operate is more consistent offshore than on land.”

Ensuring reliable supply of electricity can be problematic during the winter months due to extreme weather conditions such as low temperatures and high winds. In the U.S., a region that appears to be particularly vulnerable to these weather patterns is the New England region of six states in the Northeast section of the country.

Akdemir says, “New England represents a special location on the electric grid that is vulnerable to severe weather during the winter including cold snaps. As a result, electricity prices tend to increase with occasional price spikes as half of New England’s electricity is produced through the use of natural gas. Part of that increase is due to inadequate infrastructure and the need for using natural gas to heat residential homes and businesses.”

Very little offshore wind capacity has been operating in New England, but a new study has just been conducted to determine if having more offshore wind energy capacity might have reduced energy costs in the past even with the prospect of losing wind power during winter’s severe weather events.

UC/ED model
Akdemir and Jordan Kern, assistant professor of forestry and environmental resources at North Carolina State University, utilized a newly developed UC/ED (open-source, multi-zone unit commitment/economic dispatch) model to theoretically evaluate how the use of offshore wind energy affected the New England electric grid during an extreme cold snap that extended from December 2017 into January 2018 and also to analyze historical weather data ranging from 1949 through 2018.

The UC/ED model has the capability of taking inputs such as wind power production to minimize the cost of meeting hourly electricity demand and operating reserves in New England. The model segments New England into eight interconnected load zones that also exchange electricity with adjacent systems.

Akdemir says, “This model is designed to do electricity planning through analyzing a number of parameters including generator capacity and demand. In addition, the model indicates which generator should be used at each specific hour of the day and at what capacity.”

Figure 1 summarizes how wholesale electricity prices change for the extreme cold snap by analyzing how the actual scenario where no offshore wind power contributed to electricity production (0 megawatts [MW]) compares to two hypothetical cases that involve the use of 800 MW and 4,000 MW of offshore wind power. Akdemir says, “Our analysis in the actual case where no offshore wind power contributed to the cold snap is close to the actual outcome. Implementation of 4,000 MW of offshore wind power would have reduced wholesale electricity pricing during the cold snap on average. Even when wind speeds increased to cause offshore wind turbines to cut out, the model predicts the loss of power will only lead to a small increase in electricity pricing.”


Figure 1. If offshore wind energy was available during the extreme cold snap between December 2017 and January 2018, wholesale electricity pricing would have decreased particularly if 4,000 MW was available at that time. Figure courtesy of North Carolina State University.

For the long-term weather study, the researchers used offshore wind speed collected from the Vineyard Wind project that is currently under construction off the coast of New England for the period between 2016 and 2018. Prior wind speed data was obtained from the Nantucket Memorial Airport that is on an island off the New England coast.

Akdemir says, “We determined that adding offshore wind capacity of 4,000 MW to the New England grid between 1949 and 2018 would have reduced wholesale electricity pricing on average. The benefit would have been lower during the summer compared to the winter because of reduced wind speeds and greater electricity demand through the use of air conditioning, which would have led to higher pricing.”

In summary, Akdemir says, “Our risk analysis shows that the benefits of having offshore wind power outweigh the risks in the New England region.”

The weakness of not being able to have turbines generate electricity if the wind speed is either too low or too high is leading the researchers to consider adding electricity storage to their analysis. Akdemir says, “One potential next step is to determine how to integrate battery storage into the New England electric grid as a means to improve the reliability of the system.”

Additional information on this research can be found in a recent paper² or by contacting Kern at jkern@ncsu.edu.

REFERENCES
1. Canter, N. (2021), “Benefits of wind energy in reducing impact of climate change,” TLT, 77 (12), pp. 16-17. Available here.
2. Akdemir, K., Kern, J. and Lamontagne, J. (2022), “Assessing risks for New England’s wholesale electricity market from wind power losses during extreme wind storms,” Energy, 251, 123886.