The 300 GW Scenario
The U.S. Energy Information Administration estimates that U.S. electricity demand will grow by 39% from 2005 to 2030, reaching 5.8 billion MWh by 2030. The U.S. DOE has recently examined the issues, costs, and potential outcomes associated with expanding wind energy production to the point that it would provide 20% of U.S. electricity, or 1.16 billion Mwh, by 2030. The report concludes that a 20% Wind Scenario in 2030, “while ambitious could be feasible if the significant challenges identified in this report are overcome.”
The DOE calls this the 20% Wind Scenario. This isn’t really a 20% scenario however if we’re discussing the possibility of carbon free energy production and the electrification of nearly all energy production in the United States. As a result, I am going to refer to this as the 300 gigawatts (GW) Scenario, which is the amount the report was examining.
Ramping Up the Wind Industry
The DOE believes that achieving the 300 GW Scenario by 2030 is possible without overwhelming the ability of U.S. industry to meet those demands. The U.S. wind energy industry installed 2.4 GW of new generating capacity in 2006 and 5.2 GW in 2007. The 300 GW Scenario would require the installation of 16 GW per year after 2018. That means producing and installing roughly 7,000 turbines per year, for a total of approximately 100,000 turbines.
The United States recent experience with natural gas demonstrates that huge amounts of power generation equipment can be manufactured in the United States. In 2002 alone, more than 60 GW of natural gas power plant capacity was installed in the United States.
Capacity and Footprint
The United States has more than 8,000 GW of available land-based wind resources that the DOE estimates can be utilized economically. Under the 300 GW Scenario, 250 GW of on-shore capacity would require approximately 50,000 square kilometers (km2) of land. The physical footprint of that infrastructure would require only about 1,000 to 2,500 km2 of land—an area the size of Rhode Island.
Typically installed in arrays of 30 to 150 machines, the average turbine installed in the United States in 2006 can produce approximately 1.6 megawatts (MW) of electrical power. Larger sizes are physically possible but their use is constrained by the logistics of transporting the components via highways. Consequently, turbine capacity is likely to max out at around 3 MW to 5 MW.
The 300 GW Scenario examined by the DOE specifies more than 50 GW of offshore wind energy, mostly along the northeastern and southeastern seaboards. Based on Professor MacKay’s work I find this conclusion to be speculative. He didn’t find off-shore wind to be economically viable in England, a nation with significantly less on-shore capacity than the United States.
The 300 GW Scenario assumes that off-shore wind is 45% more expensive than on-shore wind now and for the foreseeable future. Any scenario which is unnecessarily complicated should not be considered.
The DOE concludes that in most cases it is economically more efficient to put wind projects in windier parts of the country and transmit that power to where it is needed than to locate the generating capacity at nearby, less-windy spots.
According to the DOE, it would be cost-effective to build more than 12,000 miles of additional transmission at a cost of approximately $20 billion (NPV). At least one utility company has concluded that the 300 GW Scenario would require 19,000 miles of new 765-kv transmission line at a cost of $26 billion (NPV). Either way, much of that transmission would be required in later years and it would only represent a six percent increase on the more than 200,000 miles of high capacity transmission lines in the United States.
The necessary transmission capacity would amount to approximately $3 billion per year over the next 22 years. Utilities currently spend approximately $8 billion per year maintaining and upgrading the grid. The rate impact of the transmission portion of the 300 GW Scenario could be as low as $1.30 per residential customer per month.
A Political Caveat:
The 20% Wind Scenario would require a generic change in the way transmission planning is done in many areas of the country. Numerous parties across a wide
geographic area would need to collaborate on developing a common plan instead of individual entities planning in isolation.
If the considerable wind resources of the United States are to be utilized, a significant amount of new transmission will be required. Transmission must be recognized as a critical infrastructure element needed to enable regional delivery and trade of energy resources, much as the interstate highway system does for the nation’s transportation needs. Every era of new generation construction in the United States has been accompanied by construction of new transmission. Federal hydropower developments of the 1930s, 1940s, and 1950s, for example, included the installation of integral long-distance transmission owned by the federal government. Construction and grid integration of large-scale nuclear and coal plants in the 1960s and 1970s entailed installing companion high-voltage interstate transmission lines, which were needed to deliver the new generation to loads. Even the natural gas plants of the 1990s, although requiring less new electric transmission, relied on expansion of the interstate gas transportation network. Significant expansion of the transmission grid will be required under any future electric industry scenario. Expanded transmission will increase reliability, reduce costly congestion and line losses, and supply access to low-cost remote resources, including renewables.
The DOE believes that as much as 600 GW of wind resources could be available for $60 to $100 per megawatt-hour (MWh), including the cost of connecting to the existing transmission system and not factoring in the Production Tax Credit, which reduces the cost by about $20/MWh.
“The overall economic cost of the 300 GW Scenario accrues mainly from the incremental costs of wind energy relative to other generation sources.” In other words, we’re going to need the generating capacity at some point, its just how much are we willing to pay to make it carbon free capacity?
Given the optimistic cost and performance assumptions of wind and conventional energy sources, the 300 GW Scenario could require an incremental investment of as little as $43 billion NPV more than the base-case no new Wind Scenario. This would represent less than 0.06 cent (6 one-hundredths of 1 cent) per kilowatt-hour of total generation by 2030, or roughly 50 cents per month per household…In this scenario, the cost differential would be about 2% of a total NPV expenditure exceeding $2 trillion.
The 300 GW Scenario entails higher initial capital costs than other generation sources. Wind offers lower ongoing costs however, mainly due to fuel costs. The U.S. wind energy industry invested approximately $4 billion to install 2,454 megawatts (MW) of new generating capacity in 2006. At that rate, it would cost $500 billion over the next twenty two years to install 300 GW.
The basic cost assumptions underlying the 300 GW Scenario were:
On-shore Wind: ($1,730/kW) in 2005, decreasing 10% to $1,550/kW.
Shallow Offshore Wind: ($2,520/kW in 2005), decreasing 12.5% to $2,200/kW.
Natural gas: ($780/kW in 2005)
Coal plant: ($2,120/kW in 2005) increases about 5% through 2015 and then remains flat through 2030
Nuclear plant: ($3,260/kW in 2005) decreasing 28% by 2030.
Take note of two points regarding the above assumptions. First, in this scenario carbon from coal and gas remains unsequestered. You can expect costs to double if carbon constraints are implemented. Per MacKay: (The capital cost of regular dirty coal power stations is £1 billion per GW, about the same as nuclear; but the capital cost of clean coal power, including carbon capture and storage, is roughly £2 billion per GW.)
Second, the costs listed above are per kw of capacity. The capacity is the maximum power the source can generate in optimal conditions. The actual average power delivered is the ‘capacity’ multiplied by the “capacity factor” or that fraction of the time that wind conditions are near optimal. Wind generally has a capacity factor of 30%. Nuclear has a capacity factor of over 90%. Thus, you would need to to install three times as much “wind capacity” as nuclear to achieve a given energy output.
The illustrations below demonstrate the difference between actual output and capacity under the 300 GW Scenario.
Generation by Source in 2030
Capacity by Source in 2030