Where Do I Put My Offshore Wind Farm?

By Chelsea Drenick

Offshore wind farm via Shutterstock

At the end of 2012, the European market boasted a cumulative 4,995 MW capacity from 55 offshore wind farms and the United States market boasted a total capacity of zero. As disheartening as that might sound to American renewable energy proponents, it looks like our first offshore wind farms are on the horizon (pun intended), as the production tax credits were extended, along with DOI’s Bureau of Ocean Energy Management recent announcement of $168 million in funding for offshore development. Each project awarded will receive $4 million funding for the planning phase of the project and potentially up to $47 million for the construction phase. The projects awarded are spread out across various states and sites off the coast of Texas, New Jersey, Ohio (Lake Erie), Oregon, Maine, and Virginia. Quite the spread of locations, and although this project is not listed as getting funding in the round, the first offshore wind farm may very well be the Cape Wind project off the coast of Massachusetts. The diversity of locations of planned offshore wind farms seem to beg the question, how do they decide where to put an offshore wind farm?

Wind

It may be obvious that the main factor in siting a wind farm site is the wind resource. However, determining the wind speeds that potential turbines on the site will see is a difficult and time consuming process. To accurately assess the wind resource, a tower must be constructed at the proposed site. There is information available in many locations from governmental buoys, but is generally at an elevation of 10 meters or lower, which cannot accurately be extrapolated to the 80- or 90-meter proposed hub height. So, once the wind mast is erected to measure the resource, the waiting begins. It is important to get as much information as possible about the wind seen at the site because the electricity generation of a wind farm is very sensitive to the wind speed. Your investors will not be happy if your wind predictions are artificially high because the data was only collected on a good wind year.

Water Depth

Looking at the demonstration sites awarded funding, one might notice that most of them are on the East Coast despite the seemingly high winds off the West Coast. The reason for this is water depth. The Atlantic Ocean remains relatively flat off the East Coast, making it possible to use the known technology of monopiles for foundations, which account for 73% of the constructed European wind farms. The high winds off the West Coast are seen in deeper waters, and although there is technology in development for floating turbines, no farms are in service yet that use floating foundations.

Federal Versus State Waters

The permitting process for offshore wind farms is part of the reason none have been built yet. Cape Wind’s site is in federal waters, although all their proposed roads and transmission cables are state regulated. Cape Wind finally received its last permit after a decade of applications, court cases, and waiting. Part of the length of this process was because they had to get permission on both a state and federal level, whereas many projects in the works have proposed sites in state waters to try to alleviate some of the permitting issues. The federal government is currently trying to remove some of these permitting barriers, such as by auctioning offshore leases for the first time.

Transmission Lines

A main concern with offshore wind farms is getting the electricity from the site where it’s generated to the people who will use it. A large cost in the development is the transmission lines; the longer they are, the more expensive they are. Also, the longer they are, the more energy is lost during transmission. A project is currently in the works to build an offshore transmission system off the East Coast called the Atlantic Wind Connection, partly funded by Google. This would help developers with the upfront need for a connection to the onshore grid.

Hurricane Risk

The US has seen its share of hurricanes, and you have heard of the damage they cause onshore, but they are also a serious threat to offshore oil and gas structures and will be a threat to offshore wind farms, as well. Siting an offshore wind farm must include consideration for the hurricane risk, including maximum wave height and forces the turbines will see. For example, the Cape Wind site was chosen well as a protected site from hurricanes.

Public Opinion

Public opinion has been one of the main barriers for offshore wind farm development in the United States. The Kennedy family has infamously been an opposing force against the construction of the Cape Wind project. And, as well-respected members of the community, they are supported by others. Recently, one of their family members, Joe Kennedy, has reversed his opinion and says he supports the Cape Wind project. Hopefully more Americans will begin to see the offshore wind farms in development as progress towards a renewable future.

Overall, there are many different considerations that are taken into the siting of an offshore wind farm that have so far kept a farm from being built in the United States. Some of these can’t be changed, such as the wind resources, hurricane risk, or water depth. But such issues as permitting and public opinion are already seeing improvements, and hopefully soon these issues can be overcome so that the United States can become a part of the offshore wind energy industry.