New research can help electric utilities take climate change into account
Researchers have developed a method to determine the impact of climate change on the supply and variability of local renewable energies.
An increase in unusual weather patterns linked to climate change means that demand for electricity and the availability of solar, hydro and wind power can all become more variable.
The method from researchers at the University of Alaska and Spain’s Fairbanks Geophysical Institute will help local energy planners determine the optimal mix of renewable energy sources and energy storage needs.
The research has been published in the review Ground. Uma Bhatt, professor of atmospheric sciences at the Geophysical Institute, is the lead author.
“It is important for society to understand the impact of climate change and variability on renewable energy resources in order to design a resilient power system and prepare for the future,” Bhatt said.
Researchers studied intermittency, energy production, and energy storage in the context of historical climate data at two locations: the city of Cordoba, Alaska in Prince William Sound, which has a subpolar oceanic climate, and Palma de Mallorca, a city on a Spanish subtropical zone. island. The researchers obtained 60 years of climate data for each location.
Wind, solar and hydropower are all sensitive to a climate that becomes less predictable and produces more extreme weather events. Increasing cloud cover could reduce the availability of solar power. Reduced rainfall could reduce the availability of hydroelectricity. Increased winds could increase the availability of wind energy.
Without proper planning, power grids risk becoming less reliable as renewables make up an increasingly large share of supply.
“If you have too high a percentage of high-variability renewable energy without proper backup power in your system, it actually degrades the reliability of the system a lot,” said David Newman, study co-author and professor of physics at the University of Alaska Fairbanks. (UAF) Geophysical Institute.
To further complicate the situation, energy demand changes unpredictably as the weather becomes increasingly variable. Even when demand is normal, a sudden drop in the availability of a renewable source – wind ceasing to turn turbines, for example – can cause outages if a backup source is not in place for immediate use. .
“How do you fix it? You have to find a way to remove the variability or find a way to compensate for it quickly,” Newman said.
The easiest and most obvious way is to have fossil fuel-based generators on standby. Of these, natural gas-powered generators can be started quite quickly when needed. But it is still a fossil fuel product, although cleaner than other fossil fuel sources.
Another cleaner method is to store excess energy produced by renewable sources during periods of normal demand.
Advances in technology have improved grid-scale batteries, which can store excess energy that can be distributed for short-term use during a blackout.
Other storage methods include pumped storage hydro, gravity energy storage, flywheel energy storage, and compressed air energy storage. All are basically simple methods and explained by the National Renewable Energy Laboratory.
“It’s one of the really exciting areas [of study] right now,” Newman said.
Pumped-storage hydropower accounts for 95% of all utility-scale energy storage capacity in the United States. Water is pumped from one hydroelectric reservoir to another at a higher elevation during times of excess power, raising the level of the upper reservoir. This water is released to the generators in the lower reservoir when needed.
Gravity energy storage involves using excess energy to lift massive weights made of sand, gravel, or rock and leaving the weights hanging. When power is needed, the weights are allowed to drop, their attached cables spinning a generator.
Flywheel energy storage is typically used in small applications and for much shorter energy requirements than other storage methods. Motive power spins a flywheel, a heavy wheel that spins freely when the engine loses power. The free-spinning wheel spins a generator that produces electricity for several minutes.
Compressed air energy storage can provide grid-scale electricity for several days. Electricity is used to compress and store air underground, often in salt caverns. If necessary, the air is released and heated until it expands to power a generator.
The authors of the research papers offer a notable caveat to their work: climate change is complicated and varies by location, as do available renewable energy sources.
“Climate and energy are complex, interconnected systems, and it’s important that we educate the next generation to think across disciplines so they’re ready to tackle the complex issues ahead,” Bhatt said.
– This press release originally appeared on the University of Alaska Fairbanks website