Net energy for load for 2011 was 335,000 gigawatt-hours (GWh), compared to 319,097 GWh in 2010 and 308,278 GWh in 2009.
April had the highest energy increase compared to the previous year with 14.4 percent, followed by July which increased 12.2 percent compared to last year, ERCOT said.
Typically, the spring and fall are good times to shop for electricity in Texas, because the months are known as "shoulder" months, which have moderate temperatures and do not cause high spikes in electric usage due to excessive air conditioning usage in the summer or electric space heating in the winter. Because there is less demand for electricity in these shoulder months, power prices are typically lower.
However, as shown by the spike in last April's electric usage, that paradigm is shifting, and the so-called "shoulder" months are no longer as solidly reliable for having favorable electric rates as they once were.
One of the reasons is the higher amount of wind power on the grid. Wind generation's output is variable, and although complex models forecast the production from wind generation, changes in weather can drastically alter wind generation's output in a short period of time. This can leave grid operators scrambling to replace these "lost" megawatts due to a reduction in wind power. When this happens, and other power plants have to "turn on" on short notice, wholesale electric prices can spike, leading to higher retail rates.
While wind's generation output varies throughout the year, there is less margin for sudden changes during the "shoulder" months, ironically, because demand for power is lower in these months. That's because most generators perform needed maintenance on their power plants during the shoulder months -- in the fall and spring -- because the grid can afford to have several thousand megawatts "off-line" for maintenance since peak usage is not expected. When plants are undergoing maintenance, they typically cannot start-up on short notice to respond to rapidly changing conditions, such as reduced wind output.
Having so many megawatts off-line during the shoulder months means there are fewer power plants able to respond to a sudden drop in wind generation on short notice, which can cause shortage conditions and lead to higher energy prices. In contrast, in the summer, nearly all generation is ready to come on-line to meet peak demand, with plants taken out of service only for emergencies, so shifts in wind power can be more easily filled during the summer.
Indeed, prior to last year's rolling blackouts during the February cold snap, the most recent rolling blackouts in Texas had been in April of 2006 -- a shoulder month -- because unseasonable heat and air conditioning use sent power demand past forecasts and the amount of generation available to respond. Rolling blackouts are always accompanied by record electric prices, because they indicate a shortage of electricity.
This is all to say that if Texans are holding off on shopping for an electric rate until the spring, there's a risk that prices may spike in the shoulder months. With today's electric rates still at historic lows, there is no upside to waiting three or four months to shop for power, and customers should shop for a low rate while they're still available.