Warming weather in California exposes vulnerabilities of wind power 

Is it the first signs of a serious problem for wind power generation?

Data shows a significant drop-off of wind power sales in California due to warm weather, which caused a drop in wind velocities. Is it possible that wind farms that so many believe will help mitigate the warming of a changing climate will instead be impaired by that very same warming?

The initial numbers that have emerged are striking.

First, analysts have estimated that wind speeds in the first half of the first quarter in California were off by as much as 20%, or more, from normal averages. The lower wind speeds were caused, it has been argued, by a warmer than-average winter. As is widely understood, the state is suffering from a multi-year drought and a consequent water shortage.

Data released by Vaisala, a Finnish company that studies the wind for clients developing wind projects, has been widely quoted in the last couple of months. The Helsinki-based company said it tracked and analyzed weather in the West of the US in the first quarter and said it flagged “several extreme anomalies.”

What it identified was a low wind pattern across the US, with what it said was a large blocking high pressure system over much of the West. It said the polar jet stream was also much further north compared to last year, which “resulted in above normal wind speeds in central Canada and some border states and a mild winter in much of the West.”

It also said that “weak surface pressure gradients and light southerly winds in March” were also “challenging to many projects across Texas.”

Now, the first quarter sales of wholesale wind power that owners of wind farms are required to report to the US Federal Energy Regulatory Commission are in, and the numbers are stark.

Wholesale power sales from wind generators in California in the first quarter of this year fell an eye-opening 32.7% compared to sales in the first quarter of 2014.

Forty-eight wind farms in California sold 1.304 million MWh of wind power in the California Independent System Operator market in the first quarter of 2015, compared to 1.936 million MWh sold in Q1 2014, according to data filed with FERC and other government agencies and compiled by Platts.

The roughly 630,000 MWh sales decline came despite a 197-MW increase in available wind capacity during the year. Capacity grew from 4,275 MW to 4,472 MW by the first quarter of 2015.

The state’s wind generators thus operated at a capacity factor of just 13.5% in the first quarter of 2015, a significant drop from the 21% capacity factor at which they operated in the first quarter of 2014.

The FERC wholesale wind power sales data shows that 42 out of 44 wind farms in California that had sales in the first quarter of 2014 have seen their Q1 2015 sales decline. There were four facilities that had no sales in Q4 2014.

One of the biggest declines has come at Pattern Energy’s 265-MW Ocotillo wind farm in the Imperial Valley, in the state’s most southern region. Ocotillo, which sells power to San Diego Gas & Electric, saw its sales fall 45.5% in the first quarter of this year over the first quarter of last.

The 189-MW Manzana Wind farm near Rosamond, California, in the Tehachapi area north of Los Angeles, that is owned by Iberdrola Renewables and sells its power to San Diego Gas & Electric and to the City of Santa Clara, saw its sales fall 36.7%.

Sales fell 38.3% at the 10 Alta Wind units also in the Tehachapi area that have a capacity of almost 1,400 MW of capacity.

Interestingly, at the same time of the wind sales decline, wholesale power prices in the state are not signaling a shortage of power. To the contrary, wholesale power prices are on the low side in California, largely because there has been a corresponding glut of new solar generation that has, and is, coming online in California. In fact, there have been periods when wind prices have gone to zero due to periods of power oversupply.

Nonetheless, the idea that wind generation is not only intermittent, but also vulnerable, has got to be unsettling to many wind proponents.

In the past 10 years, as wind in the US has made its run to respectability, even prominence, within the country’s power generation portfolio – there is now more than 66,000 MW of wind capacity installed in the US – hardly anyone thought or said much about the possibility that wind farms could be seriously hamstrung by warm weather.