Flip a switch and the lights come on. That’s what Americans expect, thanks to an electricity grid that feeds energy from renewable and traditional sources into millions of homes and businesses.
The wind turbines starting to go up in waters off the nation’s shores have the potential to provide abundant clean energy to heavily populated coastal cities and the larger national grid. But first, the power they generate must be relayed across many miles of ocean waters and coastline, using transmission systems that were not designed to handle large amounts of power being transmitted from offshore.
The U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) has launched plans to develop the technologies and strategies needed to integrate the coming wave of offshore wind installations into the grid. The laboratory’s success with integration — from its world-renowned work on utility-scale renewable energy systems to its comprehensive vision for offshore wind development and collaboration with industry partners — is steering efforts to deliver power efficiently and affordably from offshore plants.
“Experience integrating widely distributed, land-based renewable sources in the United States and offshore wind in Europe indicates that coordinating transmission over large regions achieves economies of scale and operational efficiencies, which can deliver considerable cost savings,” said NREL Offshore Wind Grid Integration Lead Melinda Marquis. “Challenges include cost allocation and technical demands posed by offshore locations.”
Building on the earlier DOE National Offshore Wind Energy Grid Interconnection Study (NOWEGIS), NREL plans to examine a range of scenarios for integrating offshore wind into the larger grid by assessing economic, reliability, operational, and stability factors. Researchers are looking at the interplay among transmission configurations and technologies, grid integration requirements, energy storage options, and other renewable energy sources.
Outcomes of this research will give government and industry decision-makers the validated scientific data and tools needed to establish resilient and market-competitive offshore wind power plants that deliver the greatest possible benefits to the power grid, industry stakeholders, ratepayers, and the environment.
Integrated Planning: Collaborations To Maximize Offshore Development Benefits
NREL’s research portfolio takes an integrated, whole-system approach to maximize the performance, efficiency, and impact of renewable energy, from single components to power plants and regional power grids. By quantifying what offshore wind plants can contribute to a larger regional or national network of energy solutions, researchers can help stakeholders make sure they are setting the right research, investment, and policy priorities.
Until now, utilities and offshore developers have typically considered the transmission interconnection for each wind plant individually. This project-specific approach often means developers miss opportunities to pool resources and knowledge across shared networks covering larger regions, which can improve financial viability, technical performance, and potential for long-term success.
“Large-scale development of dozens of offshore wind projects will require concerted integration of the power generation mix, including storage,” said NREL Offshore Wind Platform Lead Walt Musial. “Not only do the technologies have to work together, but regional collaborations across larger geographic regions also may be necessary for optimal system reliability and affordability.”
Policy commitments have been made to add 30 gigawatts — equivalent to approximately 3% of current U.S. generation capacity — in offshore wind generation to the grid by 2035. Many planned offshore projects are located on the North Atlantic Coast, but interest is growing in all regions of the United States, and there is great potential for synergistic development and economies of scale.
Although electric utility stakeholders recognize the importance of minimizing transmission costs, it can be difficult to determine how to spread accountability across utilities, state governments, ratepayers, and developers. If these entities can devise a way to share responsibilities such as planning for shared interconnection lines and transmission line financing, it could increase grid reliability, resilience, and efficiency; reduce project costs by as much as 10%–18%; and diminish conflicts with commercial fishing activity.
States are beginning to recognize that regional collaboration on offshore wind transmission planning can stretch budgets and strengthen infrastructure. The New Jersey State Legislature recently voted to adopt a coordinated approach by integrating offshore developments and related onshore upgrades with the regional grid operator’s planning process.
NREL researchers conduct and transmission modeling studies that evaluate the impacts of various renewable build-out scenarios on reliability, congestion, capacity value, resiliency, and related economic factors. Staff collaborate with developers, operators, utilities, government agencies, other research organizations, and coastal communities to examine offshore wind transmission options from multiple perspectives.
Integrated Technologies: Whole-Systems Approaches To Optimize Offshore Transmission Performance
Offshore wind transmission requires complex technologies that include offshore turbines, equipment to relay that power to the shore, and onshore points of grid interconnection. These connection points must be placed at locations in the larger electric grid where the power can be distributed to homes and businesses along the coast.
“Looking at how these components work together as a system, we can optimize offshore wind’s contributions to the grid,” said NREL Wind Grid Integration Lead David Corbus. “We can find innovative ways to overcome technology challenges specific to offshore installations, while improving the reliability, resilience, and performance of the overall grid.”
NREL researchers evaluate new technology and devise control methods to optimize integration of renewable energy sources with the grid. For instance, the standard approach of connecting offshore projects to existing onshore points of interconnection is inefficient and does little to improve grid reliability.
NREL is exploring innovative, multiterminal and advanced high-voltage alternating/direct-current (HVAC/HVDC) options capable of handling large-scale transmission, operating reliably despite extreme conditions related to ocean depths and climate, and reducing barriers to commercial fishing activity. The European Union has already developed some key technologies for these multiterminal systems, especially for HVDC transmission, but research is still needed to confirm the compatibility of offshore and onshore components, as well as the effects of multiterminal HVDC strategies on grid control, operation, reliability, and resiliency.
NREL’s Advanced Research on Integrated Energy Systems (ARIES) research platform, Flatirons Campus, and Energy Systems Integration Facility provide world-class, high-performance computing resources and experimental laboratories for putting these innovative offshore wind transmission technologies and strategies through their paces in various combinations, configurations, and scenarios. Sophisticated NREL-created software tools make it possible for researchers to build models and simulate performance based on the laboratory’s formidable collections of real-world data.
Integrated Vision: Partnerships To Propel Offshore Transmission Breakthroughs
Work by NREL and its partners — from recommending options for pinpointing lease areas to devising effective strategies for grid integration — continues to propel the development of offshore wind. The laboratory has developed a 10-year strategic plan for its offshore wind integration research that calls for ongoing studies in the areas of generation, transmission, storage, operation, demand, stability, and reliability.
The team is working to break down region-specific barriers to offshore wind transmission. Earthquakes, deep undersea canyons, and shortcomings in existing onshore infrastructure present complications for transmission systems along the Pacific Coast. Transmission systems on the South Atlantic Coast and in the Gulf of Mexico must contend with hurricanes and adapt to different business models less accustomed to renewable energy integration. Freezing waters and grid capacity limits also pose unique challenges in the Great Lakes.
In addition to extensive study of East Coast offshore wind scenarios, NREL is assessing offshore wind’s potential to help Hawaii work toward its goal of 100% renewable energy by 2045. Future NREL studies will look more closely at transmission “backbone” design options, where a coastal transmission grid is established that can service multiple states and offshore wind projects.
Grid integration researchers are also looking at energy storage options to address power generation fluctuations in hybrid systems capable of reliably matching load requirements using offshore wind, land-based wind, solar energy, and other renewable and traditional sources.
To tackle offshore wind grid integration challenges, NREL has joined forces with partners including the Bureau of Ocean Energy Management (BOEM), Business Network for Offshore Wind (BNOW), California Independent System Operator (CAISO), California Public Utilities Commission (CPUC), California Energy Commission (CEC), New York State Energy Research and Development Authority (NYSERDA), ISO-New England (ISO-NE), New York ISO (NYISO), Pennsylvania New Jersey Maryland Power Pool (PJM), and National Offshore Wind Research and Development Consortium (NOWRDC).
“The value of offshore wind may increase once it is integrated with the grid and other renewable generation sources,” Musial said. “Offshore wind can help diversify the electric power sector and complement other renewable sources to provide effective, affordable electricity for homes, businesses, and the growing electric vehicle fleet.”
NREL Offshore Wind Grid Integration Tools
- Distributed Generation Market Demand (dGen) model simulates behind-the-meter customer adoption of distributed energy resources for U.S. residential, commercial, and industrial entities.
- Probabilistic Resource Adequacy Suite (PRAS) measurement tool simulates outage events on the bulk power system to quantify the risk of unserved load events resulting from shortfalls in the supply or deliverability of capacity.
- Regional Energy Deployment System (ReEDS), NREL’s flagship capacity planning model for the power sector, simulates electricity sector investment decisions based on system constraints and demands for energy and ancillary services.
- Resource Planning Model (RPM) is a capacity expansion model designed for regional power systems, such as utility service territories and states.
- Scalable Integrated Infrastructure Planning Power Systems (SIIP) is a modeling framework used to build, solve, and analyze the scheduling problems and dynamic simulations of infrastructure systems.
- System Advisor Model (SAM) is a performance and financial model designed to estimate the cost of energy for grid-connected power projects based on installation and operating costs and system design.
Courtesy of NREL