As a result, officials are often forced to forgo solar power generation while the sun is shining, just hours before peak customer demand in the late afternoon and evening. The same thing happens to a lesser extent with wind energy, and the problem is emerging in many other states as well.
“It all comes down to this problem: it’s not how much energy we have, but when and where the energy is produced,” said James Bushnell, professor of economics at the University of California at Davis. “Particularly solar resources: they are only in the wrong places and at the wrong times.”
Some solar operators accept the reduction as a cost of doing business because large plants can get more sun later in the day even if they are producing excess during the sunniest hours. This can benefit consumers, who can see lower rates when solar is running, because it is generally a cheaper energy source than fossil fuels. Defenders of the system say some inefficiency is to be expected as California embarks on the nation’s most ambitious transition to clean energy and that eventually there should be enough battery to ensure excess energy isn’t wasted.
But solar and wind power generation in California is far ahead of storage capacity at this point and in some cases not near adequate transmission lines. Batteries and transmission lines can be expensive to build and find space, fueling the fossil fuel industry’s skepticism about green energy.
The need to use in order not to lose excess energy was highlighted during the record heatwave that hit California for 10 consecutive days earlier this month, breaking heat records as temperatures soared well above 100 degrees. The demand for energy increased as residents hid inside and turned up their air conditioners.
State officials have called for conservation and issued daily alerts advising Californians to limit their energy consumption from 4pm to 9pm. Officials urged residents to set their thermostats to 78 degrees during those hours and resist charging cars or using large appliances.
Despite these efforts, on Sept. 6, the state set a record for energy consumption and came dangerously close to imposing targeted blackouts to safeguard the energy grid, something that hadn’t happened for two years. State officials say they averted the blackouts that evening only by sending an urgent emergency message to the residents, who responded by quickly reducing their energy consumption.
Yet just hours ago, California had been flooded with energy. Solar production was booming in mid-morning as the sun beat down on hundreds of solar panel systems across the state. At 10 a.m., the California Independent System Operator, the state’s power grid operator, was rejecting hundreds of megawatts of solar power, unable to use it at the time, make room for it on the state’s congested power grid, or save it for later when demanded. of consumers would peak.
By 5pm, with massive consumer demand straining the grid, officials had turned down more than 3,000 megawatts of solar power. Customer demand was skyrocketing, but solar production declined as night fell and officials no longer had access to that glut of early morning solar power. However, officials managed to get through the day without a blackout by turning to other energy sources and texting residents.
Some experts have noted that extreme heat waves caused by climate change will only become more frequent, while one of the solutions chosen for climate change – renewable energy, especially solar – is not always there when we need it.
“The same technology that the state relies on to reduce carbon emissions, solar power, decreases exactly when the demand for electricity reaches its peak,” said Kyle Meng, co-director of the program for climate and l energy at the University of California at Santa Barbara Solutions Laboratory for Environmental Markets. “One of our main remedies for tackling climate change could also make us more vulnerable to the impacts of climate change.”
“The irony is that the very technology we rely on to fight climate change is making us vulnerable at times when climate impacts worsen.”
The practice of rejecting renewable energy generation is called “curtailment,” and it has increased rapidly in California in recent years – before declining slightly last year – as the state aggressively pushes to add more renewables to its energy mix, according to the calculations of the United States Energy Information Administration. In 2020, the California Independent System Operator reduced about 1.5 million megawatt hours, or 5 percent, of its total solar production, according to the EIA; last year the percentage approached 4.2%.
Anne F. Gonzales, senior public information officer at the Independent System Operator, explained via email that it “helps stabilize the network to eliminate some of the oversupply from the system.” She added that during the heatwave, Californians were encouraged to pre-cool their homes during the middle of the day, allowing them to benefit from cheap and abundant solar power during daylight hours and to set thermostats higher. afterwards.
Even so, grid operators had more solar energy available than they could use.
“People worry when there is a reduction in solar, but the reality is that we have too much renewable energy at times and not enough at other times,” said UC-Davis’ Bushnell. “If we had enough storage capacity, we could absorb that excess. … That’s where everyone hopes this will go.
In fact, battery storage has grown rapidly in California, including a huge facility in Northern California on the site of a former Pacific gas and power plant. Overall capacity doubled last year and is expected to continue to grow rapidly, aided by the tax credits included in the recent federal law on reducing inflation. The batteries went off during the heat wave, and state officials praised their performance.
Industry experts expect the amount of storage available – or potentially other uses for excess energy – will eventually increase to the point where the reduction will occur on a much smaller scale, or not at all. They note that California is undergoing a rapid energy transition, moving from a heavy reliance on fossil fuels, including coal just a decade ago, to a grid that is expected to consist of 100% clean energy by 2045. The grid of the future is in place. construction in real time, with inefficiencies and perverse incentives still in the process of smoothing out.
“I think of the reduction as an important indicator of how more storage space will be added,” said Alex Morris, executive director of the California Energy Storage Alliance, an industry group. “In California, we see increasing amounts of storage every year that are absorbing and positioning themselves to capture extra energy.”
Another possible solution to the oversupply of renewable energy would be a mass shift in consumer demand so that residents use electricity in the middle of the day rather than in the afternoon or night, said Severin Borenstein, director of the faculty. of the Energy Institute at the Haas business school of the University of California at Berkeley. This has been discussed by policy makers, but would require the cooperation of utilities to redesign tariff structures.
In Texas, where wind power is reduced in enormous quantities, many of the same questions have arisen around the practice. Some wonder how excess energy can be used on-site at wind or solar plants, obviating the need for transmission somewhere else. Bitcoin mining and mobile data labs have been proposed as possible candidates for absorbing excess energy.