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Closing the Green Gap

Will wind power close the gap between state renewable portfolio standards and the current shortfall in viable technologies?

Fortnightly Magazine - April 2005

Today there are 20 states plus the District of Columbia in which renewable portfolio standards (RPS) or mandatory renewable quotas have been established. During the past several months, six additional states formally have considered renewable standards but have not yet initiated programs.

The RPS rules vary significantly across states in terms of qualifying fuel types, credit trading, incentives, targeted goals, and the time frame for compliance. Today the RPS states represent 52.6 percent of the nation's retail electricity revenue. These states account for virtually all of the current production of solar, wind, and geothermal power generated in the United States annually.

Global Energy's recent multi-client study, Renewable Energy: The Bottom Line , estimates the gap at 118,400 GWh between operating non-hydro renewable electric (NHRE) output today and that required in 2020. This gap translates into new renewable capacity by 2020 of 52,729 MW, with 76 percent expected to come from wind because of attractive economics and resource availability. The cumulative capital investment is estimated at $53.4 billion.

Chart 1 - RPS Impact – Energy Shortfall

Moreover, according to the Electric Power Research Institute, there is a concern that the current pace of innovation in all of today's power generation technologies—fossil, nuclear, and renewable—will not be sufficient to meet many other economic or greenhouse gas reduction needs.

Of course, the energy shortfall is sensitive to a number of factors including the: a) expected load growth in each state; b) most likely mix of renewable development in each state based upon resource availability and cost; c) forward view of the capital costs of each technology; and d) expected capacity factors for each technology. So how sensitive are our findings to these assumptions? We used our RPS toolkit to calculate the following sensitivities:

  • Load-growth sensitivities :

o Reference case based on individual state-level assumptions, resulting in a 1.8 percent national average;

o At 1 percent per year, the gap falls to 46.8 GW needed at a cost of $46.9 billion;

o At 3 percent per year, the gap grows to 74.7 GW needed at a cost of $74.3 billion-a variance of $27.4 billion.

  • Sensitivity to capacity factors for wind projects :

o Reference case uses 30 percent capacity factor for new wind plants, and the wind shortfall alone is 40 GW-at a cost of $36 billion;

o At 25 percent wind capacity factor, the wind gap grows to 47.6 GW at a cost of $42.7 billion;

o At 35 percent, the wind gap shrinks to 34.6 GW at a cost of $31.1 billion.

  • Sensitivity to Renewable Energy Credit (REC) trading :

o Reference case assumes no trading, resulting in a gap of 52.7 GW at a cost of $53.3 billion;

o With trading, the gap falls significantly to 38.9 GW needed at a cost of $39.4 billion-a savings of $14 billion.
  • Sensitivity to a