Eastern Wind Study from NREL Provides An Important Step Forward

Today the National Renewable Energy Laboratory released a new wind integration study titled the Eastern Wind Integration and Transmission Study (EWITS). The study examines the infrastructure needed to increase the share of wind energy to 20-30% (today wind is about two percent of US electricity). The report is significant in that it shows the importance of including offshore wind in a large scale integration study. EWITS also makes clear that a large amount of transmission will be needed to deliver enough wind to meet a 20-30% goal (especially from southwest portion of the eastern grid). It is an important step forward, but only one of many as much still remains to be done in this area. 

The "Eastern Interconnect" is the biggest of the three independent US grids (the eastern grid accounts for over 70% of the electricity consumed in the US), which means that reaching high wind penetrations in East requires a lot of turbines. EWITS projects that about 340,000 MW of wind power will be needed to reach wind penetrations of 30%. In terms of maximum output power (i.e. installed capacity) that's equivalent to more than 400 large conventional power plants. 

EWITS shows that this level of wind deployment is a major challenge, not only due to the number of wind turbines, but also because of the thousands of miles of new power lines needed to get that electricity to market. Installing a large amount of wind requires substantial investments in new transmission lines because the best resources aren't in areas of high population density.  We can look at the EWITS wind projections per region as a fraction of total demand for electricity to get a sense of how much this level of wind development would overwhelm existing power infrastructure:

Regional wind capacities in EWITS scenarios divided by 2006 peak load by region

This figure shows that in the Southwest Power Pool (SPP), the amount of wind in EWITS Scenarios 1, 2 and 4 is equivalent to more than 2 times the total peak power needs in the region. The amount of wind projected in SPP far outstrips all previous wind integration scenarios. In fact, a wind integration report for SPP released yesterday looks at wind deployment scenarios up to 25 GW (40% wind in SPP), which is only half of what EWITS projects, even in their least onshore-intensive scenario (Scenario 3), and less than 30% of the wind deployment projected in the other scenarios. The level of grid infrastructure development needed to maintain system reliability with such a high amount of wind clearly represents a major challenge.

What's new here?

There have been a large number of wind integration studies done in the past (a good review is here), but most of them have had limited geographic scope and resource base. Last year the Joint Coordinated System Plan (JCSP) took an important step forward by providing a model of the entire eastern interconnection in their high penetration wind scenario modeling. EWITS builds on this earlier work but takes another important step forward, looking not just at onshore wind resources, as the JCSP had done, but also integrating offshore wind resources.

Wind Resources in EWITS Scenario 3

Offshore wind is, potentially, an enormous source of power that is often relatively close to population centers, thereby reducing the amount of transmission needed to integrate large amounts of wind into the grid. Scenario 3 in EWITS is an aggressive local/offshore case with over 64 GW of offshore development. Its results project that a 20% wind penetration can be reached with 25% fewer miles of new transmission relative to the all-onshore wind case (Scenario 1). 

The conclusion one can draw from the EWITS study is that offshore is a potentially critical resource that can have significant impacts on how we decarbonize the electric power sector and reduce the scope of infrastructure development that will be required to support a large deployment of renewables on the system. 

The study also makes clear, however, that this does not eliminate the need for transmission to bring wind power from the Midwest. Even in the aggressive offshore case, over 17,000 miles of new transmission are needed including over 12,000 miles of the highest voltage AC (765kV) and DC (800kV) lines. Midwest onshore wind is the cheapest source of utility-scale renewable energy available in the East; offshore wind doesn't obviate the need to exploit onshore resources and it certainly doesn't eliminate the need for transmission. 

What's Next?

EWITS, like the JCSP before it, signifies an important step forward in our understanding of how variable generation can be integrated to the grid in large quantities. But there is still much that remains to be done. The addition of offshore wind resources is only the first step in understanding the full range of options available to facilitate the integration of renewables.

An aggressive deployment of energy efficiency, demand response, energy storage, distributed generation, and improved systems operations (e.g. dynamic thermal rating, increased system scheduling frequency, conditional firm services) can go a long way toward integrating variable generation into the system. EWITS takes one step in this direction by looking at the impact of consolidated balancing authorities (control areas) on wind balancing, but there is certainly more study needed to identify the full portfolio of options available to integrate wind.

As system planners start to undertake the interconnection-wide planning funded by the stimulus, these kinds of modeling exercises will form an important foundation for the analysis needed to extend wind integration studies into system planning and, eventually, implementation. Newer efforts, such as NREL's SolarDS model development, will help to better integrate rooftop and wholesale distributed solar into these kinds of modeling efforts. Also, the EWITS sister study in the west has begun to look at how utility scale solar and wind can both be deployed in large quantities. 

The challenges we face are enormous. Planning tools have been extended to unprecedented geographic scope and have begun to integrate a wide range of new resources into the generation mix. But we must still push to look at all supply *and* demand side resources at our disposal and simultaneously plan for ever-broader time horizons to meet the challenges of addressing climate change and transitioning to a clean energy economy.