NREL

Biocoal Options

A new future for small coal-fired plants.

Small coal-fired plants are particularly vulnerable to economic and environmental pressures, putting some plant owners in what seems like a no-win position. But an emerging option—biocoal from crop wastes—might give small coal units a new lease on life.

PURPA's Changing Climate

California defends its cogen feed-in tariff—complete with its own virtual carbon tax.

California’s new feed-in tariff (FIT) is creating a burgeoning market for green energy investments, but the policy has sparked a fierce battle over state authority to dictate wholesale power transactions. A federal case will determine whether the 1978 Public Utility Regulatory Policies Act pre-empts states from requiring purchases that exceed utilities’ avoided cost.

Beyond Intermittency

Forecasting brings wind energy under control.

Advancements in forecasting have improved the reliability of day-ahead and hour-ahead estimates of wind generation. Wind never will behave like a base-load power plant. But as system operators integrate wind forecasts into their planning and market processes, they’re transforming intermittent wind energy into a variable but reliable resource.

Solar Expansion

Technologies are scaling up quickly to meet industry needs.

Like other California electric utilities, San Francisco-based Pacific Gas & Electric (PG&E) has been scrambling to meet the state’s renewable portfolio standard (RPS), which requires suppliers to obtain at least 20 percent of their power from renewable energy sources by 2010. Though the RPS includes a variety of technologies, renewables developers are choosing utility-scale solar power more than any other resource, says Hal La Flash, PG&E’s director of emerging clean technologies.

Buying Into Solar

Rewards, challenges and options for rate-based investments.

Utilities traditionally have met renewable portfolio standards with power purchases from IPPs. But new approaches are allowing utilities to build their rate bases with investments in solar generation.

Capturing Ocean Heat

Ocean thermal energy conversion offers a timely renewable alternative.

23 million square miles of tropical oceans daily absorb solar radiation equal in heat content to about 250 billion barrels of oil. Ocean thermal energy conversion technologies convert this solar radiation into electrical power by exploiting the thermal gradient temperature differences between the surface and the depths. This enormous resource merits a closer look as policy makers consider alternative technologies for serving future energy demands.

Carbon In Electricity Markets

Price transparency will drive GHG reductions.

In light of coming GHG legislation, price transparency is the key to achieving cleaner generation through the dispatch of lower-carbon sources.

Redefining PV Capacity

Effective metrics give solar its due credit.

Photovoltaic (PV) power generation is an intermittent, non-dispatchable resource generally considered as energy-only with no capacity credit. However, there is ample evidence that solar energy reliably is available at peak demand time when loads are driven by day-time commercial air conditioning, and can contribute effectively to increasing the capacity available on a regional grid.

Green Price Stability

New approaches account for the economic benefits of renewables.

Many green power customers benefit from long-term fixed prices. The most effective programs recognize the value of this price hedge—and fairly exempt customers from fuel cost adders in utility rates.

Riding on The Wind

Plug-in hybrids usher a new era for wind power.

Plug-in hybrid vehicles (PHEVs) open a new intersection between wind power and transportation.