As Rhode Island prepares to build the first offshore wind farm in the U.S., I got to wondering why it was being built out in the ocean rather than on land.
The farm, which will be constructed by a company called Deepwater Wind, will lie off the coast of Block Island and feature five wind turbines that will be able to provide 30 megawatts (MW) of power. That’s enough energy to meet the needs of all Block Island residents while cutting their electric rates in half. Another benefit is that the new wind turbines will spare Block Island from burning more than a million gallons of polluting diesel fuel each year.
Putting up wind mills or turbines in the ocean is nothing new – if you live in Europe. But in the U.S., they’ve been controversial, especially on Cape Cod, where citizens have objected to installing turbines because, among other issues, they’ve worried that towering windmills will destroy their picturesque ocean view. The Rhode Island wind farm could set an example for other wind development, not only along the eastern seaboard but around the Great Lakes, as well.
Whether onshore or offshore, wind offers many benefits over coal, oil, and natural gas. Because it is not fossil fuel-based, wind generates no carbon dioxide or air pollutants. An investment in wind pays back very quickly. Based on a 40% estimated efficiency, the payback time for construction of a 40.5 meter wind turbine for an off-shore wind farm is only 0.39 years, less than 2% of its 20-year life span.
What’s more, the supply of wind power is free and abundant. Scientists at Harvard University estimate that global wind power potential is 40 times greater than total current power consumption! In the lower 48 states, reported the New York Times, the potential from wind power is 16 times more than total electricity demand in the U.S.
Further, wind power requires no drilling, mining, refining, or transporting. There will be no cleaning up of oil spills, or worrying about coal mines collapsing or groundwater being contaminated as it is from fracking.
Finally, notes Triple Pundit, when a wind turbine reaches the end of its useful life, it can be dismantled. It will not leave a long-term toxic legacy like nuclear power, tar sands oil, or coal.
Windmills have been around for thousands of years, but they’ve only been “industrialized” relatively recently as citizens and communities have looked for cleaner energy alternatives. In the U.S., most windmills have been built “onshore,” on land in primarily rural areas of the country where it is sufficiently windy to generate substantial power. However, building windmills “offshore,” either on floating platforms or on concrete slabs in shallower water, is becoming a serious part of the conversation, especially as the impacts of climate change become more apparent and more people embrace the idea of building clean and safe alternatives to fossil fuels.
Which gets me back to my original question:
How do offshore and onshore wind farms compare?
Pros of Offshore Wind Compared to Onshore Development
- Quieter: Some people complain that wind turbines are noisy, but when the turbines are located offshore, the noise is not noticeable.
- Less Obvious in the Landscape: Land-based wind turbines are large and some people who live nearby have been concerned that the turbines loom or cast a shadow over their communities. Offshore turbines, especially those sited 5 to 15 miles offshore as they could be in some areas, would be far less obvious.
- More constant source of power: One problem with wind power is that it only works when the wind is blowing. Wind is more constant at sea than it is on land in most parts of the U.S.
- More efficient: According to the Wind Energy Center at the University of Massachusetts, the “…wind resource potential at 5 to 50 nautical miles off the U.S. coast is estimated to be more than the total currently installed electrical generating capacity of the entire United States.”
- Proximity to Demand: Offshore can compete in highly populated coastal energy markets where onshore wind energy is generally not available.
- Less Wear and Tear on Equipment: Because the wind blows faster and more uniformly at sea than on land, that faster, steadier wind means less wear on the turbine components and more electricity generated per turbine.
- More Efficient Energy Transmission: Since winds increase rapidly with distance from the coast, excellent wind sites exist within reasonable distances from major urban areas, reducing the onshore concern of long distance power transmission.
- Greater Potential To Reduce Overall Electricity Bills for Consumers: Offshore wind resources are nearer to the states that pay the highest electricity rates in the United States, so have the potential to reduce electricity costs the most.
Pros of Onshore Wind Compared to Offshore
- Proximity to Existing Electrical Grids: Onshore wind farms are often closer to existing electrical grids, so reduce the need to build new electrical grids and minimizing the amount of electricity that may be lost during transmission.
- Cheaper Construction Costs: It is currently cheaper to build and maintain onshore wind than offshore wind.
- Availability for Small Power Consumers: Onshore wind that is far from coastal areas nevertheless enables homes, schools, commercial and industrial facilities, telecommunications, farms and ranches, and communities to meet their energy needs via wind power.
- Onshore Wind Power Continues to Grow: While the U.S. has yet to build its first offshore wind farm, onshore wind power generation has grown on average by 27% per year. There is ample experience building and operating wind farms of various sizes. Far fewer technological unknowns surround building an onshore facility than building offshore.
It’s Not Either/Or, But Both
The White House and the U.S. Department of Energy have released a report showing that wind can be one of America’s top sources of electricity, potentially providing 20% of US electricity by 2030 and 35 percent by 2050. That is more likely to happen if we develop both onshore and offshore wind farms.
Onshore wind will continue to expand because the technology works and it is already cost competitive with polluting fuels like coal. However, offshore wind farms may be inevitable. The federal Bureau of Ocean Energy Management has designated a region off the coasts of Rhode Island and Massachusetts a wind-management area. Over time, offshore wind turbines there could generate as much as 9,000 MW of wind power – 300 times the amount expected to be produced by the Block Island turbines.
Whether on land or on sea, wind will play an important role in providing clean, safe, renewable energy future for our families.