Sea-Bed Air Batteries Offer Affordable, Long-Term Energy Storage

Israeli firm BaroMar is gearing up to trial an inventive approach to grid-level energy storage, aiming to provide the most cost-effective solution for stabilizing renewable grids over extended periods. Their innovative system harnesses the power of water.

In the envisioned zero-carbon energy grid, the interplay of various renewable sources like solar and wind will be key. However, as their output won’t always align with demand, effective energy storage and release mechanisms become crucial. These solutions must cater to various time frames, from daily fluctuations to longer stretches, such as periods of prolonged cloudy weather affecting solar output.

Addressing the Long-Term Storage Challenge with Innovative Compressed Air Energy Storage (CAES

Then there’s the challenge of long-term storage, which aims to store surplus electrons for the winter months, when solar generation experiences a seasonal decline that wind power alone may not compensate for. This is the aspect that BaroMar aims to tackle with its unique approach to compressed air energy storage (CAES).

CAES typically involves using surplus energy to operate compressors, which pressurize air and store it in large, sturdy containers. When needed, the pressurized air is released through a turbine connected to a generator to recover the stored energy. While CAES is already considered a cost-effective energy storage method, BaroMar claims it can outperform traditional systems for long-term storage using a surprisingly simple solution.

Essentially, the company’s facilities will be strategically located along coastlines with access to deep water. Instead of employing large, costly high-pressure tanks, BaroMar utilizes the pressure exerted by the water column to store compressed air in more economical enclosures.

Their setup involves a series of sizable, affordable, straightforward concrete and steel tanks, each topped with cages filled with rocks to maintain submersion at depths ranging from 200 to 700 meters (650 to 2,300 feet).

Tank Configuration and Operational Dynamics of BaroMar’s Underwater Compressed Air Energy Storage (CAES) System

The tanks are equipped with water-permeable valves and initially filled with seawater. Nearby on dry land, the compressor and generator systems activate when surplus energy is available.

The compressor then channels ambient air into the tanks through extended hoses at pressures ranging from 20 to 70 bar (290 to 1,015 psi), depending on the depth.

The tanks expel water as compressed air is introduced. Because the water’s external hydrostatic pressure offsets the internal air pressure, these tanks don’t need the same strength or cost as land-based tanks facing high-pressure internal air against atmospheric pressure outside.

During energy retrieval, air ascends the hose into a thermal recovery system, then drives a generator via a turbo-expander. Meanwhile, water rushes back into the tank, ready for displacement during compressor operation.

Targeted Efficiency and Pilot Project Scale Designed by Jacobs for BaroMar’s Underwater CAES System

Engineering consultancy Jacobs, designing a Cyprus pilot project, targets a round-trip efficiency of about 70%. This mirrors the efficiency of the world’s largest CAES plant in Zhangjiakou, China. Despite its smaller scale, storing just 4 MWh, this underwater project promises notably high efficiency compared to conventional systems.

Cost Efficiency Projections of BaroMar’s Underwater CAES System Compared to Other LDES Technologies

BaroMar claims superior cost efficiency compared to other long-duration energy storage (LDES) options due to its sturdy, cost-effective tanks and minimal underwater maintenance expenses. Forecasting the operation of a 100 MW/1 GWh system for 350 days yearly over twenty years, BaroMar anticipates achieving a Levelized Cost of Storage (LCoS) of US$100 per MWh, contrasting with an estimated $131/MWh for “other LDES technologies.”

Undoubtedly, developing a system meant for long-term underwater operation presents challenges. Jacobs, handling the project’s design, acknowledges the considerable hurdles ahead. Vice President Fiachra Ó Cléirigh emphasizes the necessity for extensive surveys, feasibility studies, and permits for tank installation and onshore equipment placement in deep waters.

Nevertheless, affordable and scalable solutions are crucial for future renewable energy grids.

If BaroMar’s concept proves successful, it could be applicable in various coastal areas, given the proximity of many cities to the sea. The advancement of this project warrants close attention.

Read the original article on: New Atlas

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