A Wind Developer’s Guide to the Transmission Grid

This is the second in a two-part series on wind-farm development. The first article, entitled Advice for first-time developers, discussed some of the regulations and challenges of wind-farm site selection. While many developers put time and consideration into new project siting, permitting, turbine selection, and financing, transmission is sometimes an afterthought. However, transmission considerations are just as important as finding the right project site. Here’s why.

Wind-farm development is a complex process. As a new wind project progresses through various stages of development, there are many opportunities for mistakes that can seriously affect its final outcome and success. Some of the biggest mistakes in wind development begin in the early stages and are difficult to overcome as the project progresses.

Poor site selection is all too common with new developers. Sites are chosen for the wrong reasons, such as location preferences or without sufficient due diligence. They are also ill chosen for lack of consideration of the grid or transmission capabilities.

Transmission lines may be located near a potential new wind-farm site, but gaining access to the lines is another matter that can prove challenging and costly. There have been plenty of new developers who’ve secured a project site and permits only to find out nearby transmission lines cannot carry more load. Ensuring that a site is ideal for a new wind farm includes asking important questions related to the grid, such as:

  • Wtransmission-system-operationhat transmission lines are nearby, and what is their available capacity?
  • How accessible is the grid, and have other developers showed interest in gaining access to the transmission in the area?
  • What transmission upgrades (and costs) are necessary to accommodate a new wind project?
  • Who will buy the wind power once connected to the grid?
  • If planning to sell to a local utility, can the power get delivered directly using nearby lines or are multiple systems required for power delivery?


Understanding the grid

A transmission grid is one of the most complicated engineering systems devised by man. It is complicated technically in terms of how electrons flow from generators to the load (or end user), and contractually in terms of how costs are allocated. The process of gaining access to the transmission system is also complicated and costly.

Much like securing a project site, when developing a new wind farm it is imperative to conduct similar due diligence on the local transmission system. Research the local infrastructure and look into proposed upgrades to transmission systems and substations. Also consider potential long-range plans for large transmission projects and the overall system operations for the region.

Here is a step-by-step guide for getting your new wind project connected to the grid. Although this process will vary from one system operator to the next, the general steps are similar.

  1. The Interconnection request
    You have located what seems an ideal site for a new wind farm and may have already started a wind-resource assessment campaign. Next, it is time to ensure the power produced by turbines can efficiently and cost-effectively find its way to electricity users. This process typically starts with an interconnection request. Your position in the queue (other interested developers are often in the area) is determined by the date of the request, and receipt of a non-refundable pre-payment for a feasibility study.
  2. The feasibility study
    This study is generally required to assess the viability of the transmission lines and capacity for the proposed project. Its purpose is to determine with minimal effort, time, and cost whether there is a reasonable likelihood that the interconnection request can be satisfied. Remember to set aside resources for this process. The cost of a study is typically in the range of $5,000 to $50,000. This range reflects the size of the project scope, grid access, and number of transmission lines in the area. The study itself does not usually take long and, on average, completes in less than a month. However, this is dependent on the number of study requests in the queue and it could take a year before your study request makes it to the front of the line.
  3. System impact study
    If a feasibility study is given the green light and the interconnection request accepted, the next step involves a system impact study. Note, this step will cost more and take longer to complete. The typical cost could range from $20,000 to over $100,000, depending on the size of the wind farm. And expect it to take up to six months or longer to complete once your request has made it to the front of the queue (this could also take a year or longer).As its name implies, the purpose of a system impact study is to consider the potential system impacts that may affect local transmission lines and the overall grid from injection of new wind energy from your project. Essentially, this study will determine:

    • The minimum amount of interconnection service available for the proposed new wind project — without the need for system upgrades.
    • When upgrades or reinforcements are necessary to handle your full request, a detailed list of what they are including a high-level cost estimate for them.
    • A rough timetable for when transmission access could be granted.To properly complete a system impact study, it is necessary to have detailed information about the exact wind turbines planned for your project. If you didn’t start your wind-monitoring campaign early enough, you may not yet have enough information to choose the ideal turbine make and model for site. When this is the case, you will have to wait until the wind assessment is complete, potentially wasting time and your place in the queue, so plan accordingly.
  4. The facilities study
    If you’ve managed to successfully make it through steps two and three, the next stage involves a detailed facilities study. This study is quite involved and will help determine what equipment is needed to reinforce the grid to accommodate your project. A facilities study provides developers, utilities, and transmission owners and operators with a precise list of upgrades, costs, and timetables for interconnection and improvements if necessary. It also tells when you’re able to gain access to the transmission system. Typical costs for this study range from $50,000 to over $100,000, and could take six months to a year to complete.
  5. The transmission service request
    If your proposed wind-farm project makes it through to this point and has proven technically and financially feasible from a grid standpoint, you are now in a position to make a formal transmission service request. This request is for the right to use a specific amount of capacity on the grid to deliver wind-generated power from one location to another. It is a good sign and means your wind project is ready to go from a transmission viewpoint, but it won’t come cheap. Expect to make a substantial payment for this service (think: hundreds of thousands of dollars).
    Wind development is certainly not for the faint of heart. As mentioned in Part 1 of this series, if you intend to sell power to a local utility once the wind farm is up and running, it is a good idea to open up a dialog early on and maintain realistic expectations regarding the anticipated power pricing. Transmission studies alone are costly and time consuming. The late stage of project development is a less than ideal time to learn there are no interested buyers for the output from the wind farm.Many potential transmission-related risks crop up along the way. Seeking advice from knowledgeable transmission experts early on in the development process can avoid some of the many pitfalls that could derail a project.

This article was published in the September 2016 issue of Windpower Engineering & Development magazine