Most utility reserve margins are adequate to meet peak demands. That is the assessment of the North American Electric Reliability Corp. (NERC) as the nation has hit the summer months in which heat can strain supplies.

Even in a stumbling economy, consumers continue to demand vast amounts of electricity. Meanwhile, uncertainty surrounds the nation’s aging delivery system as it relies more heavily on renewable sources of power. Utilities have managed to maintain what is considered to be an adequate level of resources despite these challenges.

The conclusions reflect NERCs 2012 Summer Reliability Assessment. In the report, NERC finds that capacity resources have increased across the country by approximately 12,310 megawatts (MW) since summer 2011. In contrast, projections for total peak demand are about 3,700 MW lower than they were at the same time last year. The most notable increases in capacity were within the areas of the SERC Reliability Corp. and the Northeast Power Coordinating Council, two of nine regional electric reliability councils under NERC. NERC also noted enhanced operations and planning approaches that were instituted in response to San Diego Gas & Electric’s Sept. 8, 2011, outage.

Despite the positive news, NERC identified several potential problems. Variable generation, which is power from renewable sources, continues to comprise a greater proportion of generation in most areas of the country. This poses challenges for reliability and transmissions. It also asserted that getting customers to conserve through demand-side management will be the key to maintaining reliability this summer.

Focusing on specific areas, NERC warned that the unanticipated outage of the San Onofre Nuclear Generating Station earlier this year and other transmission issues make some portions of the Southern California grid vulnerable to stress under extreme weather conditions. It added that lower global liquefied natural gas supply may affect generation in New England. Lastly, it projected that planning reserve margins in the region served by Electricity Council of Texas (ERCOT) will be below the NERC Reference Margin Level, the threshold by which resource adequacy is measured. As a result, extreme conditions could lead to rotating blackouts to maintain reliability over the summer.