Can California have too much solar?
California set two records of renewable energy last week: the most solar power ever flowing on the main electrical grid of the state, and the most solar power ever taken offline because it wasn’t necessary.
There is no contradiction: as California utilities are increasingly buying solar power as part of the state’s quest to tackle climate change, supply and demand are becoming progressively out of sync. Solar farms and rooftop panels commonly produce more electricity from the state’s fleet than Californians use in the center of the day — a phenomenon that has sent lawmakers and some climate proponents scrambling to discover methods to save additional sunlight rather than waste it.
But in fact, an excess supply of solar power could be a nice thing for ratepayers.
New study published in Solar Energy’s peer-reviewed journal indicates that California should adopt the concept of constructing more solar panels than it can continuously use, rather than treating excess supply as a issue to be solved. It sounds counterintuitive, but deliberately overbuilding solar facilities — and accepting that they will often need to be dialed down in the lack of adequate demand — may be the best way to maintain electricity rates low on a renewable energy-dominated power grid, the study discovered.
New York-based scientists Richard Perez and Karl Rábago argue in a research released in March that solar energy has become so cheap that overbuilding it is likely to be the cheapest way to maintain the lights on during cloudy or overcast days— cheaper than relying completely on batteries. Solar power can fulfill high daily demand for electricity without storing energy, scientists say, as long as there are sufficient solar panels on the grid during times when none of them produce at complete capacity.
“It’s not like solar will be accessible all the time,” said Perez, an expert on solar energy at Albany’s New York State University. “You’ll need storage at night, and you’ll need storage on cloudy days. But you will need much less. “California has set a target of 60% renewable electricity on the power grid by 2030, as well as a 100% climate-friendly energy long-term goal, a wider definition that could include hydroelectricity or nuclear power. A dozen other states and U.S. territories have embraced or are considering comparable 100% clean power objectives, and they will be observing the advancement of California as they attempt to find out how to realize those objectives.
The success of the Golden State relies partly on attaining its objectives without sending rising energy prices. Although low levels of energy use mean monthly bills are comparatively small, California already has some of the largest electricity rates in the country.
Perez and Rábago co-authored their research with analysts at Clean Power Research, a California and Washington state-owned company. The research was based on an previous Clean Power Research report, which indicated that in Minnesota— a country not known for abundant sunlight— the cheapest way of running the energy grid with solar panels, wind turbines and batteries engaged the construction of so many solar panels that their production would have to be “curtailed” or decreased by around 30 percent below what they would otherwise be able to produce.
The study discovered that electricity would be slightly cheaper than it is today in Minnesota under a range of high-curtailment situations— a conclusion that Perez and Rábago found true for many energy grids.
Models run by the California Public Utilities Commission, looking at the choices of the state to reduce planet-warming emissions while preserving reliable and inexpensive electricity, also discovered that a solar power surplus makes sense.
“What the models said was to overbuild solar dramatically, and export it when you have excess production or curtailment,” said Edward Randolph, who leads the energy division of the regulatory agency. The argument for overbuilding solar power is not new, nor is it particularly contentious among scientists studying the logistics of transitioning from fossil fuels to cleaner sources of energy. Utility regulators have always constructed additional power into their planning, requiring on the grid adequate electrical generation ability to guarantee that nearly always enough power is on hand to satisfy the demand for energy.
This reserve margin has traditionally come from fossil fuels. Renewables overbuilding is a comparable notion.
However, some specialists are skeptical about Perez and Rábago’s sheer scale of overbuilding.
Wade Schauer, a Sacramento-based investigator at Wood Mackenzie’s power consulting company, said Perez and Rábago did not take into consideration the expensive transmission lines that might be required to accommodate solar overbuilding, or the landowner resistance that frustrated solar farmers in California and elsewhere. The scientists also presumed that power storage expenses will stay “laughably high,” said Schauer — an assumption that makes batteries look less appealing than solar overbuilding.
California received 34 percent of its electricity from renewable sources in 2018, estimates the state’s Energy Commission, not counting manufacturing from solar panels on the rooftop, which would add several percentage points. In latest years, solar power has risen particularly quickly, driven by falling expenses, federal tax credits, and California’s mandate for renewable energy.
The primary power grid of the state set a record for most concurrent solar generation just before midday on June 1, breaking prior records set in April and May. According to the California Independent System Operator, which operates the primary power grid of the state, increasing quantities of solar power have been followed by increasing curtailment.
Solar and wind farms on the California grid produced 223 less gigawatt-hours than they would otherwise have in May, with the vast majority of the losses being caused by solar. That’s enough electricity to power about 400,000 average homes in California, and more than twice as much curtailment as any month before this year. Due to an influx of inexpensive hydropower after a humid winter, the figures are particularly high in part.
Solar plant operators shut down a record total of about 4,700 megawatts of power at the same moment on May 27 at around 1 p.m. — approximately 40 percent of the total California grid installed solar power.
Those figures sound big, but still comparatively low, said Mark Rothleder, vice president of market performance and regulatory affairs for the grid operator.
Less than 2% of future solar generation has been curtailed in 2018, Rothleder said, a figure that this year could reach3%-4%. The vast majority of curtailments occur in a competitive market, where operators of solar and wind power plants are paid to ramp down manufacturing. In rare cases, the grid operator will order certain installations to ramp down manually.
Rothleder considers some overbuilding as a nice thing, as it gives the grid operator flexibility. Instead of depending completely on gas-fired power plants to ramp up and down to meet demand swings, the non-profit agency can be creative with solar farms, curtailing their manufacturing as required, or keeping some solar in reserve for moments when energy demand could suddenly jump.
The main issue is how much additional solar power is useful and how much money is wasted. Rothleder said that overbuilding and curtailment are no replacement for the kinds of measures that California will eventually need to take to fully replace fossil fuels with clean energy, such as investing in large energy storage projects, sharing more solar and wind power with neighboring countries, and developing electricity rates that encourage individuals to change their energy use to times of day when the sun is shiny.
“If (curtailment) begins to inch up to 10 percent and exceeds 10 percent, you need to begin looking at it and ask what else you can do,” said Rothleder. “At that point, I don’t think just building more solar is the right thing to do.” Sacramento lawmakers discussed the types of steps described by Rothleder, but they didn’t find much consensus.
For example, the Legislature dismissed then-Gov again last year. Jerry Brown’s renewable energy sharing plan across the West. The proposition would have unified the region’s disparate power grids, decreasing curtailment by enabling more sharing across state lines of renewable energy, but lawmakers feared that California might lose its sovereignty over its energy supply.
More lately, a proposal that would require enormous quantities of large-scale, long-term storage of electricity— a sort of storage for which lithium-ion batteries are not well suited — was taken from the Senate floor, with concerns that it would burden customers with high expenses and support a contentious hydropower project near Joshua Tree National Park.
These suggestions were partly motivated by the increasing alarm about curtailment and the revelation that California sometimes pays other countries to carry their surplus solar power. For example, Ralph Cavanagh of the Natural Resources Defense Council last year wrote that lawmakers should support Brown’s regional power grid plan because “wasting increasing quantities of clean energy from our state is no way to promote the ambitious energy and climate objectives of California.” Part of the issue with these discussions is that it is difficult to predict what distinct technologies will cost in the comin. Perhaps solar will continue to get cheaper, and the cost of batteries will not drop as much as analysts expect. Or perhaps not.
“If you believe you understand what all the resources ‘ expenses and working features will be in 20 years ‘ time, we can write fancy computer models that will optimize everything. But we really don’t understand, “said Bushnell. “Too many studies are circulating, meaning we’re doing it.”
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