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January 24, 2010

Closer Look at the National Renewable Energy Report on Achieving 20% Wind Energy


The Eastern Wind Integration and Transmission Study (EWITS) is one of the largest regional wind integration studies to date. It was initiated in 2008 to examine the operational impact of up to 20-30% energy penetration of wind on the power system in the Eastern Interconnect of the United States.

the full report is a 242 page pdf

The executive summary of the report is 48 pages long

The Capacity Factor blog looked at the NREL report. Capacity Factor blog pulls out more of the cost comparisons. See the linked article.

The cost figures quoted in the media are wrong. The figures are annualized - they are costs per year. Second, they are the costs for the entire scenarios including the 80% of electricity that is NOT wind. The figures actually says is that the cheapest 20%-wind scenario costs about $15 billion/year more, everything included, than the reference case. Here is everything together in figure 8.2 (p. 211) - where the $140/$143/$155 billion figures came from:





Some of The Actual Report Details

A brief description of each scenario follows:
• Scenario 1, 20% penetration – High Capacity Factor, Onshore: Utilizes high-quality wind resources in the Great Plains, with other development in the eastern United States where good wind resources exist.

• Scenario 2, 20% penetration – Hybrid with Offshore: Some wind generation in the Great Plains is moved east. Some East Coast offshore development is included.

• Scenario 3, 20% penetration – Local with Aggressive Offshore: More wind generation is moved east toward load centers, necessitating broader use of offshore resources. The offshore wind assumptions represent an uppermost limit of what could be developed by 2024 under an aggressive technology-push scenario.

• Scenario 4, 30% penetration – Aggressive On- and Offshore: Meeting the 30% energy penetration level uses a substantial amount of the higher quality wind resource in the NREL database. A large amount of offshore generation is needed to reach the target energy level.

The study team also developed a Reference Scenario to approximate the current state of wind development plus some expected level of near-term development guided by interconnection queues and state renewable portfolio standards (RPS). This scenario totaled about 6% of the total 2024 projected load requirements for the U.S. portion of the Eastern Interconnection.

Translation of the last paragraph. A business as Usual (BAU) estimate for wind energy is that there would be 6% wind power for 2024 in the Eastern United States.
Supplying 20% of the electric energy requirements of the U.S. portion of the Eastern Interconnection would call for approximately 225,000 megawatts (MW) of wind generation capacity, which is about a tenfold increase above today’s levels. To reach 30% energy from wind, the installed capacity would have to rise to 330,000 MW.

In general, though, the study shows the following:
• High penetrations of wind generation—20% to 30% of the electrical energy requirements of the Eastern Interconnection—are technically feasible with significant expansion of the transmission infrastructure.

• New transmission will be required for all the future wind scenarios in the Eastern Interconnection, including the Reference Case. Planning for this transmission, then, is imperative because it takes longer to build new transmission capacity than it does to build new wind plants.

• Without transmission enhancements, substantial curtailment (shutting down) of wind generation would be required for all the 20% scenarios.

• Interconnection-wide costs for integrating large amounts of wind generation are manageable with large regional operating pools and significant market, tariff, and operational changes.

• Transmission helps reduce the impacts of the variability of the wind, which reduces wind integration costs, increases reliability of the electrical grid, and helps make more efficient use of the available generation resources. Although costs for aggressive expansions of the existing grid are significant, they make up a relatively small portion of the total annualized costs in any of the scenarios studied.

• Carbon emission reductions in the three 20% wind scenarios do not vary by much, indicating that wind displaces coal in all scenarios and that coal generation is not significantly exported from the Midwest to the eastern United States; carbon emissions are reduced at an increased rate in the 30% wind scenario as more gas generation is used to accommodate wind variability. Wind generation displaces carbon-based fuels, directly reducing carbon dioxide (CO2) emissions. Emissions continue to decline as more wind is added to the supply picture. Increasing the cost of carbon in the analysis results in higher total production costs.

The scenarios developed for EWITS do not in any way constitute a plan; instead, they should be seen as an initial perspective on a top-down, high-level view of four different 2024 futures. The transition over time from the current state of the bulk power system to any one of the scenarios would require additional technical and economic evaluation, including detailed modeling of power flows and a study of the effects on the underlying transmission systems. A more thorough evaluation of the sensitivity of the EWITS results to the range of assumptions made would also be required to guide the development of any specific bottom-up plans.



The report has not looked at any cost changes or improvements for any of the energy sources. There are advancements being made in China for coal, General electric and others are increasing natural gas power plant efficiency, and nuclear power reactors being developed in China, Russia, India and South Korea and other places could greatly reduce costs.






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