Human error appears to have caused a partial shutdown on Friday of the South Texas Project, one of the state”s two nuclear plants.

It’s been an eventful few days for the Texas power grid. Since last week, prices have spiked in the wholesale electricity market, one of the units of a major nuclear plant tripped off due to “human error,”  and Texans broke another record for energy usage.  Given the comparatively high electric prices already paid by Texans and concerns over continuing problems with the deregulated market, the developments merit examination.

Here they are, in no particular order:

*On Monday, wholesale electricity that more typically sells for less than $30 per megawatt-hour spiked to more than $2,000.  That’s an increase of more than 7,000 percent. Prices also spiked several times to the $1,000 level. A price spike for $2,200 is especially startling, given that the regulatory cap is set at $2,250. That is, the wholesale prices legally could not have gone much higher. In most other jurisdictions the caps are set no higher than $1,000 per megawatt hour.

*According to the organization that manages the power grid, the Electric Reliabiilty Council of Texas, a new record for statewide power use was set on Monday. It was the fourth new usage record in as many weeks. ERCOT reported that the new record was broken at about 4 p.m., when demand spiked to 65,715 megawatts. The usage spike came just as the spot market price was spiking to $2,200 — probably not a coincidence.

*Unit 1 of the South Texas Project apparently tripped off on Friday. The event, first reported in a trade journal SNL Power Daily, was apparently caused by human error. “The NRC said in its Aug. 23 event report that the unit experienced an automatic reactor trip that was caused by an inadvertent turbine signal initiated during testing,” reported SNL”s Jay Hodgkins, citing the U.S. Nuclear Regulatory Commission. The publication reported that power was restored by Monday. It’s unclear whether the outage contributed to the price spikes, although that seems likely.

*In response to the loss of a major unit on Friday,  ERCOT activated the first stage of its emergency response procedure to prevent blackouts. That means that some industrial consumers that previously agreed to have interruptible service lost their power.  It was the third time this year that ERCOT has gone to that stage of its emergency response procedures.  The major unit that went down was probably the nuke (as referenced in the SNL Energy article) although ERCOT won’t say for sure. That”s because such a disclosure would violate ERCOT”s rules for competitive information.

The developments are unsettling, especially given that wholesale prices tend to trickle down to residential consumers. A dysfunctional wholesale market can lead to higher home lighting bills. Already Texans pay more than consumers in Oklahoma, Louisiana and Arkansas. Prices also remain higher than the national average. Prior to deregulation, Texans paid below the national average.

— R.A. Dyer