Hydrostor’s GEM A-CAES has received a conditional loan guarantee of up to $1.76 billion from the US Department of Energy (DOE) to build the Willow Rock Energy Storage Center, a cutting-edge compressed air energy storage (CAES) system, in Eastern Kern County, California.

If everything goes as planned, Willow Rock will bring 500 megawatts (MW) and 4,000 megawatt-hours (MWh) of long-duration energy storage (LDES) to the southern California power grid.

This system will lower energy costs, improve grid reliability during peak demand, and expand the rollout of renewable energy into the grid. Here’s how it works and why it’s unique.

How compressed air energy storage works

CAES technology is all about storing energy for later use, especially when the sun isn’t shining or the wind isn’t blowing. Here’s how it works:

1. Storing energy: The system takes surplus energy (often from renewable sources like solar or wind) and uses it to compress air, which is stored in underground caverns.
2. Releasing energy: When the grid needs power, the compressed air is released, passing through a turbine to generate electricity. Willow Rock will be able to dispatch stored energy at full power for over eight-hour periods.

Unlike conventional batteries, CAES can scale up based on the size of the storage cavern and doesn’t rely on scarce critical materials. It’s durable, too –systems like Willow Rock are designed to last over 50 years.

Why advanced CAES is different

Traditional CAES systems face two big challenges: wasted heat and inconsistent power output. Willow Rock’s advanced compressed air energy storage system (A-CAES) technology solves these problems:

• Thermal energy capture: Conventional CAES loses around 50% of energy during the air compression process. Willow Rock pairs a proprietary thermal storage system with this process, so it captures, stores, and reuses heat from the compression cycle.
• Constant Pressure: Traditional systems lose efficiency as underground air pressure drops. Willow Rock maintains consistent pressure by using water from an above-ground reservoir. As a bonus, the facility will be a net producer of fresh water, as water condensed during the compression process will be captured and reused.

This innovative design means A-CAES systems can be installed in a greater variety of underground conditions – an estimated 80% of US geology could support similar systems, opening the door for wide deployment.

Willow Rock will create up to 700 construction jobs at its peak, and 40 full-time operations roles will follow. These positions require skills similar to those used in the oil and gas industry, making it a natural fit for Kern County, a region with roots in fossil fuel production.

GEM A-CAES is a subsidiary of Hydrostor USA Holdings, a subsidiary of Hydrostor of Canada.

Read more: The world’s highest solar + storage project is online in Tibet

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Chinese EV automaker Build Your Dreams (BYD) has unveiled its ATTO 2 compact SUV to the European public. The launch, which took place at the Brussels Motor Show, kicks off BYD’s next EV entry into European and UK markets. The BYD ATTO 2 is smaller and more affordable than its SUV siblings, with a decent range to boot, perfect for European roads.

The ATTO 2 is a rebranded version of the Chinese EV automaker BYD’s Yuan Up – an ultra-affordable compact SUV that debuted in China in February 2024. BYD may not be bringing “Yuan” branded EVs over to new markets in Europe, but that lineup continues to grow each month.

BYD currently sells four all-electric models in the UK and seven in Europe, including the ATTO 3 SUV. Today, BYD debuted a rebranded version of the Yuan Up called the ATTO 2, which will go on sale to customers in the UK and Europe next month.

BYD unveils ATTO 2 in Brussels, sales begin in February

The Brussels Motor Show recently kicked off as the first major automotive expo in Europe in 2025, and BYD showed up with a new affordable BEV option to complement the ATTO 3. Per BYD executive vice president Stella Li:

We’re excited to start 2025 with another important model for our plans in Europe. The B-segment SUV class is incredibly popular here, and with the ATTO 2, we have an agile and versatile offering that will appeal to that large potential customer base. It takes all of BYD’s strengths in batteries, electric motors and Cell-to-Body construction and combines them in a compact package that brings new intelligent technologies to the urban SUV class.

The ATTO 2 is 4,310mm long, 1,830mm wide, and 1,675mm tall—145mm shorter and 45mm slimmer than its ATTO 3 sibling. Despite its compact size, the ATTO 2 offers up to 1,430 liters of cargo capacity with its rear seat down.

The ATTO 2 also sits atop BYD’s e-Platform 3.0, the first of the brand’s compact SUVs to utilize Cell-to-Body (CTB) construction, which integrates the battery completely into the vehicle chassis—this design results in optimized space and overall increased vehicle rigidity.

Speaking of batteries, the EU and UK customers who opt for an ATTO 2 can experience BYD’s proprietary Blade Batteries, which integrates LFP cells directly instead of fitting them into multiple modules. BYD says customers can choose between two battery sizes in their ATTO 2 order. At launch, a standard range edition will utilize a 45.1 kWh Blade Battery, delivering a (WLTP) 312 km (194 miles) range.

However, BYD said a larger-battery version of the ATTO 2 will arrive in the coming months and offer drivers greater range. The automaker is not yet sharing individual pricing for the ATTO 2 in the UK or Europe. Still, a representative for the company said the compact SUV is expected to land between the BYD Dolphin and ATTO 3 BEVs, which in the UK cost 26,140 GBP ($32,157) and 37,140 GBP ($45,689) respectively.

ATTO 2 sales are expected to begin in February.