The heat wave in Texas continues, as does the threat of rolling blackouts

The heat wave in Texas continues, as does the threat of rolling blackouts:

Texans are being asked to conserve electricity as the The Electric Reliability Council of Texas (ERCOT) saw its operating reserves dropped below 2,300 megawatts due to the extreme heat.

“We are asking Texas residents and businesses to reduce their electricity use until 7 p.m. today,” ERCOT vice president Kent Saathoff said in a press release.  “We don’t expect to need additional steps in the emergency procedures today unless we lose a significant amount of generation over the peak period.”

Later, in a conference call with reporters, Saathoff suggested that students returning to school this week might have contributed to an increase in power consumption as districts turned on lights and turned down A/C systems.

If the situation worsens, ERCOT could declare a Level 2A emergency would trigger large factories, mostly along the Gulf Coast, to power down their operations in a bid to preserve energy reserves.  But Saathoff said he doesn't expect that to happen today, because we have made it through the hour of peak consumption, 4 p.m. to 5 p.m.

In a worst case scenario, ERCOT initiates a Level 3 emergency, which involves rolling blackouts across the state. Local electric utilities implemented rotating outages of 15 to 45 minutes in length. Hospitals and other essential services are not supposed to lose power.

ERCOT Delcares Level One Energy Emergency August 23, 2011

The heat wave that hit Texas is causing extreme demands on the electrical grid. ERCOT is urging customers to reduce their power consumption at the risk of rolling blackouts.

Texas is at a Level 2a power emergency as operating reserved dropped below 1,750 megawatts. ERCOT (Electrical Reliability Council of Texas) pays larger customers to be dropped first in the event of a power emergency, but, if overall loads don't decrease, Texas moves to Level 3 and rolling blackouts will ensue.

Texas Heat Wave: ERCOT Warns of Power Outages August 24, 2011

EARLIER: This afternoon, the Electric Reliability Council of Texas announced they are in “Energy Emergency Alert Level 2,” meaning they have asked certain industries to shut down their power usage - or else Texans could face rolling power outages. Conservation is now critical, ERCOT says.

Austin Energy spokesman Ed Clark explained the alert as what happens when the state’s energy reserves, optimally at 3,000 megawatts, drops below 1,500 megawatts. They’re now asking certain power users like refineries or big companies to shut down power usage to get the grid back to normal, Clark said.

ERCOT power emergency canceled August 24, 2011

ERCOT's website Actual Loads of Weather Zones Report indicates that on Tuesday, August 23, 2011 the peak load was 67136 MW at 5 pm and on Wednesday, August 24 2011 the peak load was at 66552 MW, once again at 5 pm.

This implies that the operating capacity on Tuesday was 69436 MW (67136 + 2300) and 68302 MW (66552 + 1750) on Tuesday and Wednesday, respectively.  I don't know what the 1134 MW difference operating capacity was between Tuesday and Wednesday.  Maybe a plant was down for maintenance? Or maybe is just the inherent variability in  the wind-portion of the Texas grid's electricity supply?

In any event, this bears following.  If the desired reserve is at least 3000 MW and the operating capacity can fluctuate by over 1000 MW, then it is easy to see how these alerts, and possibly rolling blackouts, will become part of everyday life.  If a power plant broke down or the wind was especially calm, then rotating outages of 15 to 45 minutes in length in the late afternoon during the summer will also become common place.