Kotzebue Electric Association’s 576-kilowatt solar farm is the biggest distant solar farm in Alaska. (Amanda Byrd)
A rise in unusual weather patterns related to climate change means the demand for power and the supply of solar, hydro and wind energy can all turn out to be more variable.
The strategy by researchers on the University of Alaska Fairbanks Geophysical Institute and in Spain will help local energy planners determine the optimal mixture of renewable energy sources and energy storage needs.
The research was published in August within the journal Land. Geophysical Institute atmospheric sciences professor Uma Bhatt is the lead creator.
“It can be crucial for society to know the impact of climate change and variability on renewable energy resources as a way to design a resilient power system and prepare for the long run,” Bhatt said.
The researchers studied intermittency, power production and energy storage within the context of historical climate data at two locations: the Alaska city of Cordova in Prince William Sound, which has a subpolar oceanic climate, and Palma de Mallorca, a city on a subtropical Spanish island. The researchers obtained 60 years of climate data for every location.
Wind, solar and hydropower are all vulnerable to a climate that’s becoming less predictable and producing more extreme weather events. Increased cloud cover could decrease the supply of solar energy. Decreased precipitation could reduce the supply of hydropower. Increased winds could increase the supply of wind power.
Without proper planning, power grids risk becoming less reliable as renewables make up an increasingly larger portion of the provision.
“If you might have too high a percentage of high-variability renewable power without appropriate backup power in your system, it actually degrades the system’s reliability quite a bit,” said David Newman, a study co-author and physics professor on the UAF Geophysical Institute.
Further complicating the situation, the demand for power changes in unpredictable ways because the weather becomes increasingly variable. Even when demand is normal, a sudden drop in the supply of a renewable source—wind ceasing to show the turbines, for instance—may cause blackouts if a backup source shouldn’t be in place for immediate use.
“How do you fix it? You’ve got to seek out a solution to remove the variability or to have a solution to quickly compensate for it,” Newman said.
The best and most blatant way is to have fossil fuel-based generators on standby. Of those, generators powered by natural gas could be began fairly quickly when needed. But it surely’s still a fossil fuel product, though cleaner than other fossil fuel sources.
One other, cleaner method is to store excess energy produced by renewable sources during times of normal demand.
Advances in technology have improved grid-scale batteries, which might store excess power that could be distributed for short-term use during a widespread blackout.
Other storage methods include pumped storage hydropower, gravity energy storage, flywheel energy storage and compressed air energy storage. All are fundamentally easy methods and explained by the National Renewable Energy Laboratory.
“That is one in every of the really exciting areas [of study] without delay,” Newman said.
Pumped storage hydropower accounts for 95% of all utility-scale energy storage capability in the USA. Water is pumped from one hydropower reservoir to a different at a better elevation during times of excess power, raising the extent of the upper reservoir. That water is released to the generators of the lower reservoir when needed.
Gravity energy storage involves using excess energy to lift massive weights consisting of sand, gravel or rock and leaving the weights suspended. When power is required, the weights are allowed to fall, with their attached cables turning a generator.
Flywheel energy storage is often utilized in small applications and for much shorter energy needs than other storage methods. A motor powers a flywheel, a heavy wheel that spins freely when the motor loses power. The freely spinning wheel turns a generator, which produces electricity for several minutes.
Compressed air energy storage can provide power on a grid-scale for several days. Electricity is used to compress and store air underground, often in salt caverns. When needed, the air is released and heated to expansion to power a generator.
The research papers’ authors offer a notable caveat to their work: Climate change is complicated and varies by location, as do the available sources of renewable energy.
“Each climate and energy are interconnected complex systems, and it will be significant that we educate the subsequent generation to think across disciplines so that they are prepared to deal with the complex problems which might be looming,” Bhatt said.
Publication Referenced within the Article:
Uma S. Bhatt et al, The Potential Impact of Climate Change on the Efficiency and Reliability of Solar, Hydro, and Wind Energy Sources, Land (2022). DOI: 10.3390/land11081275
This text was written by the team on the University of Alaska Fairbanks.