COP29: The energy storage challenge for key renewable power pledge

• Countries to be asked to boost energy storage at COP29
• Battery storage key to expanding renewables
• World aims to triple renewable energy by 2030

LONDON - Azerbaijan, the host of this year's U.N. COP29 climate summit, wants governments to sign up to a pledge to increase global energy storage capacity six-fold to 1,500 gigawatts by 2030 in a bid to boost renewable power.

The proposed pledge follows a goal set at last year's COP28 meeting to triple renewable energy capacity by 2030 - which the International Energy Agency (IEA) has said would be feasible if countries moved quickly to deploy more electric grid connections and battery storage. 

Tripling renewable energy capacity and doubling energy efficiency measures could reduce global planet-heating emissions by 10 billion metric tons by the end of the decade compared with what is otherwise expected, the IEA has said.

Here's what you need to know:

What is energy storage and why is it necessary?

Storing power is vital to expanding renewable energy because it can supply electricity to consumers when the sun is not shining or wind is not blowing, and battery farms help integrate clean energy into power grids.

Batteries are expected to account for 90% of the rise in global energy storage by 2030. 

The rest will be covered by something called pumped hydropower, which involves pumping water to the higher of two reservoirs, then passing it down to the lower reservoir through a turbine when energy is required.

Lithium-ion batteries are currently the most economically viable energy storage solution, but a number of other technologies are being developed, such as compressed air, superconducting magnets, underground pumped storage and hydrogen storage.

Car manufacturers say electric vehicle (EV) batteries could be recycled once exhausted and reused in electric grids. A slew of startups are already working in this field. 

But this alone will not meet global needs as there is also competition for those used batteries from recyclers and refurbishers, while some drivers may not trade the batteries in as quickly as anticipated.

What are the problems linked to battery manufacture?

The batteries required for battery storage include rare minerals, like lithium, nickel and cobalt. Demand for these metals could quadruple by 2040 if the global energy sector achieves net zero CO2 emissions by 2050 - according to an IEA estimate.

But in many countries, mining critical minerals has been linked to environmental pollution and labour abuses, according to environmental and rights activists.

Bolivia, Argentina, and Chile hold over half the world's lithium, but mining activities have prompted protests demanding greater benefits for local communities, such as public works projects or royalties. 

Africa has 30% of the world's mineral reserves, many of which are needed for the green transition, including cobalt in the Democratic Republic of Congo where the industry is dogged by allegations of abuses, particularly related to artisanal mining. 

Abuses have also been reported in mineral mining in Indonesia and the Philippines - the world's top two nickel producers.

What role could EV batteries play?

One option proposed to boost energy storage is by recycling EV batteries. Globally, there are at least 80 companies involved in EV recycling, with more than 50 startups attracting at least $2.7 billion in investment in recent years.

The amount of EV batteries available for recycling could satisfy short-term grid storage globally as soon as 2030, if the right infrastructure is in place, according to research published last year in the Nature Communications journal.

However, ensuring that drivers participate in programmes is challenging, and more people are keeping their cars after the batteries' capacity falls below 80-85%, which usually happens after eight to 10 years.    

Which countries are leading the field in battery storage?

Battery projects in the hundreds of megawatts are becoming more common. Such large systems exist or are under development in California, Florida, Australia, the United Kingdom and China.

Investment in grid-connected batteries in China leapt 364% last year, according to Carbon Brief.

In California, one of the largest battery storage gigafactories has been built near Los Angeles and is due to come online this year. 

Calpine's billion-dollar Nova Power Bank will be able to power about 680,000 homes for up to four hours when charged.

(Reporting by Adam Smith; Editing by Jack Graham and Clar Ni Chonghaile.)