Generating Electricity from Renewables: Crafting policies that achieve society's goals

I. Executive Summary

Twenty-five states have indicated their dissatisfaction with the current electricity generation system by enacting binding renewables portfolio standards (RPS). They require that wind, solar, geothermal, biomass, waste or other renewable resources be used to generate up to 30% of the electricity sold by 2025. While the authors applaud using renewables to advance important social goals, we caution that forcing too rapid implementation of these technologies could lead to blackouts or unnecessarily high prices.

One reason for caution in forcing rapid deployment of renewables is that large scale wind and solar generation is qualitatively different from using fossil fuels, hydro-electric, or nuclear. Unlike the technologies that have served the industry for a century, wind and solar generation are variable and they generally do not generate electricity when demand is highest. In addition, generating companies face difficulties in fulfilling the RPS goals by the required dates. Getting sufficient wind turbines would require a major increase in manufacturing capacity, since there is about an 18-month delivery delay at present. Siting the wind farms and getting the power to market may be even more difficult because, while the public supports renewables in principle, there is formidable opposition to siting wind turbines and transmission lines. Cost is still another difficulty. Transmission costs can easily double the cost of delivered power. The fact that wind and solar generally do not help meet peak demand means that dispatchable generation is needed for peak demand and so renewables don't reduce the investment in dispatchable power, but rather only reduce fuel use. The variable nature of wind and solar generation requires backup generation or storage to fill the gaps when the wind dies or clouds obscure the sun. The low capacity factors for wind, and especially solar, mean that if they were the only means of meeting the 15-25% RPS, much of the renewable generation would be spilled until large scale electricity storage and transmission lines become much less expensive.

The authors favor continuing to press renewable technologies to solve, or at least mitigate current generation problems, but warn that eagerness to get the benefits of renewables must be tempered with recognition that forcing the timing increases costs and could reduce reliability. However, time pressure can raise costs and make it impossible to attain specified goals. The authors also urge increased R&D expenditures on these technologies, particularly on bulk storage of electricity, to increase reliability and drive down costs. We stress that dispatchable electricity at affordable costs is essential for the economy and our lifestyles. Legislators and regulators must monitor RPS implementation to prevent blackouts or electricity prices that threaten our economic health. Finally, we urge that, rather than focus on a mandate for renewable electricity, the focus should be on all appropriate technologies that meet the goals of pollution and carbon-dioxide abatement, healthy economic development, energy security, and a reliable electricity system that delivers power at a price that doesn't penalize consumers or the economy. In addition to renewables, the technologies may include conservation, more efficient generation, fossil fuels with carbon capture and sequestration, and nuclear power.

There are likely to be two problems in meeting near-term RPS mandates: timing and cost of electricity.

TIMING

A combination of subsidies and requirements for small quantities of renewable power has provided incentives that have increased wind's share of generated electric energy to 0.6% of total USA generation and geothermal's to 0.4%. The renewable portfolio standards enacted by states require large increases in those percentages in a short time. Seven years from now, in 2015, eighteen states require that at least 10% of their electricity must come from renewables. California and New York require 25%. Meeting these requirements requires that huge numbers of these power plants be constructed. By 2015, New York must build 10,400 MW of new renewable power, an increase of 26% in its existing generation (that required a century to build). Illinois has legislated that 8,000 MW of new renewables be constructed, a 19% increase in its existing generation. Connecticut requires 1,700 MW of new renewables by 2015, an addition of 21% to its fleet of power plants. Massachusetts has one of the most ambitious near-term requirements: it requires that 3.5% of all electricity be renewable this year, with a half percent increase every year (the requirement is not being met, and utilities are paying penalties that they pass through to customers).

This magnitude of power plant building is not unprecedented, but it is not common. With the exception of the natural gas plant boom-and-bust construction cycle in 1999-2001, these building rates have not been achieved in any seven-year period in a quarter century. Assuming that current manufacturing and skilled labor shortages can be overcome, land use issues for renewable generation facilities and transmission are likely to cause delays in meeting RPS requirement dates. Illinois has mandated that 75% of their RPS be met by wind. This will require negotiations with the owners and neighbors of 1,000 square miles of land on which to site turbines.

In keeping with society's impatience to solve electricity's problems, the RPSs mandate investment that will stretch, or even exceed, industry's ability to meet the goals. For example, a new wind turbine ordered today may not be delivered for 18 months or more. Negotiating land leases and permits often takes years. Unless production facilities for wind turbines are expanded several-fold, the RPS requirements in aggregate cannot be met by the time required in the statutes. In February 2008, Congress refused to extend the production tax credit for renewable electricity beyond the end of 2008, discouraging investments in manufacturing capacity.

Getting renewable power to customers will be delayed by the need to extend transmission lines and get permission to interconnect (in some states, interconnection study delays are projected to last a decade or more). Getting the right of way and permission to build transmission lines is notoriously difficult. For lines more than 50 miles long, the median time to obtain permission and build the line has been 7 years, not accounting the lines that never got permission.

States have passed renewables portfolio standards, but have not grappled with what is required to implement them: siting of generators and transmission lines in the time required by the RPS. As currently legislated, many states' RPS deadlines, especially those for 2015 and earlier, are unlikely to be met unless legislators in Congress and state capitals force change in permitting, obtaining the land and permission to build wind farms and transmission lines, and provide the resources to review interconnection applications quickly. While the public appears to support these goals in the abstract, individuals object vociferously to wind farms in some places and to transmission lines nearly everywhere. In a democracy it is hard to imagine that elected representatives would ignore these intense objections, e.g., the wind farm off Cape Cod.

COST

Wind is the fastest growing renewable resource. Electricity can be generated by wind turbines for an unsubsidized cost of 8-8.5 cents/kWh. Current wholesale daily weighted average power costs in Texas have ranged from 4-7 cents per kWh, 6-8 in Pennsylvania, 8-10 in New England, and 7-9 in California. Thus, the wholesale cost of wind power appears to be competitive in some locations. However, there are three principal problems with wind. The first is that good wind sites are generally located far from load centers. Transmitting the electricity 1,000 miles from wind site to city would double the delivered cost. The second is that the wind generally doesn't blow when electricity demand is high. The capacity factor of all the wind turbines used to generate utility power in the United States has been 21% over the past decade (the best wind locations have a capacity factor of 40-50%). Thus, investment in wind does not lower the amount of dispatchable capacity needed, i.e., the amount of capacity that can be turned on when the demand is high. Wind power saves fuel for other generators, but, for example, if wind supplied 15% of the electricity, it would save considerably less than 15% of fuel. The third is that wind is variable. Rather than wind turbines producing a steady stream of power, electricity from a wind turbine fluctuates continually. If wind produced much of the power required by an RPS, needed transmission, backup generation, and storage to control for variability would increase the cost considerably.

In good locations geothermal power is almost competitive with fossil generation. However, the best locations are clustered in the Southwest. Even there, transmission lines increase the time and cost to bring power to cities.

Biomass might cost-effectively supply a few percent of electricity generation, using farm waste, wood waste and thinnings, and energy crops that used little farm land, if supply chain, delivery, and processing issues can be resolved. Like geothermal, biomass electricity could be almost competitive with fossil generation. However, biomass is excluded from some RPS legislation, generally on the grounds that the most cost-effective use is co-firing biomass with coal, a fuel unfavored by RPS proponents.

The most popular renewable with the public is solar power, either photovoltaic (PV) or solar thermal. Current PV has a non-subsidized cost of 33-61 cents/kWh*, almost ten times the cost of the current electric power generation mix. There are niche applications where solar PV dominates, but the current cost of PV makes it more a subject for basic research than widespread deployment. Solar thermal is cheaper, but, without subsidy, is not competitive except in special applications.

Many current laws assume that public and private R&D will bring down the costs of renewables; for solar photovoltaic they implicitly assume costs will fall by almost a factor of ten; some specify a technology, assuming that the legislature can predict the success of future R&D.

Since renewable sources are variable, when they are used at large scale they will be matched with natural gas turbines to supply steady power. Thus, renewable portfolio standards will increase natural gas demand and its price, increasing the cost of electricity.

RPSs are designed to speed the introduction of new renewable installations. Without careful planning, forced speedups can raise costs by requiring equipment makers to pay overtime to meet demands and by not allowing time for engineers to improve design in the next generation of facilities. The technology improvements in renewables have been significant. However, forcing the installation of facilities before they can benefit from R&D will raise costs. Finally, the current electricity system is not configured to accept rapid deployment of renewables. New transmission lines and approval for interconnections are needed. The former often take decades to get approved and built; MISO has indicated that they will not be able to review all the current applications for connecting wind and other renewables within a decade. The authors favor continuing to press renewable technologies to ensure that social goals are pursued, but warn that eagerness to get the benefits of renewables must be tempered with recognition that forcing the timing increases costs and could reduce reliability.

CONCLUSION

The authors fear that pressing the introduction of renewables too aggressively would result in high cost, unreliable electricity, leading to a public backlash against these policies. Less aggressive policies favoring renewables in the USA and the rest of the world have brought down the costs of these technologies. The authors favor continuing to press renewable technologies to attain social goals. Attaining the full range of social goals is important, including having an electricity supply that is adequate, reliable, and affordable; electricity is essential for our economy and society. Renewables can help meet the goals, but they are not the only technologies that can; conservation, increases in generation efficiency, fossil fuels with carbon capture and sequestration, and nuclear power can help attain the goals. Increased R&D for these technologies is promising, particularly for bulk storage of electricity. Rather than specifying the technology, the authors urge Congress and state legislatures to specify the goals: lower air pollution and greenhouse gas emissions, lower depletion of fossil fuels, increase energy security, and shift to a more sustainable generation mix that produces an adequate supply of reliable, reasonably priced electricity. Since no current technology meets all goals, legislators need to consider tradeoffs. Specifying the goals, rather than the technologies, will lead to a technology race that will serve society.

 * These costs are without the cost of supplying fill-in power when the solar PV arrays are not producing power. The lower number assumes 8% capital charge rate, $5400/kW, 20 year life, and 20% capacity factor. The higher cost changes the capacity factor to 14% and uses a 12% cost of capital.