Battolyser Systems (€70 million to develop battolyser technology for storing renewable energy in rechargeable battery and hydrogen fuel)

Battolyser Systems, a Dutch cleantech startup established in 2021, has developed an innovative integrated battery and electrolyser system called the battolyser. This technology efficiently utilizes surplus renewable electricity by charging the battery component. Once the battery reaches full capacity, any additional energy is directed towards the production of hydrogen and oxygen for energy storage. The Battolyser's design allows for optimal capture and utilization of wind and solar energy resources.

Challenges: renewable energy storage

As awareness of climate change and the need to reduce greenhouse gas emissions, the global installation of renewable energy sources, such as solar cells and wind turbines, has increased. Global cumulative solar PV capacity reached 1.6 TW by the end of 2023. New solar PV installations in 2023 were 447 GW, an 87% increase from the 239 GW installed in 2022. Global cumulative installed wind power capacity reached 1.047 TW by the end of 2023. New wind installations in 2023 totaled 116 GW, a 34% increase from 2022.

The inherent variability and intermittent output of wind and solar power present significant challenges to their widespread adoption. Solar energy, for instance, demonstrates a notable fluctuation in electricity generation, with peak production occurring during daylight hours and summer months, while output diminishes substantially at night and in winter.

Battolyser Systems Technology

Rechargeable batteries have emerged as promising candidates for short-term grid balancing due to their high roundtrip efficiency (85-95%), scalability, and flexibility. While numerous battery systems have been developed over the past century, only a select few, primarily lead-acid and lithium-ion batteries, have been successfully implemented in large-scale applications.

Historically, lead-acid batteries dominated the market, offering advantages of low maintenance requirements and cost-effectiveness. However, their widespread adoption has been hindered by:

• Limited cycle lifetime (500-800 cycles)
• Low energy density (30-50 Wh kg⁻¹)
• Toxicity concerns
• Poor high-rate performance with long charging times (8-15 hours)

By 2017, lithium-ion batteries had captured 90% of the large-scale battery storage market. They have advantages of extended lifetime (>1000 high depth of discharge cycles), superior high-rate performance (charging time <1 hour), and high energy and power density (170-250 Wh kg⁻¹). However, for stationary applications, the high energy and power density of lithium-ion batteries are not critical requirements. In addition, the following factors limit the grid-scale applications of lithium-ion batteries:

• High material costs
• Low robustness
• Sensitivity to overcharge and deep discharge
• Risk of thermal runaway
• Need for expensive additional safety and cooling systems
• Discharge limitation to 80%

The EU SET plan defined as target properties for the grid-scale battery system:

• Lifetime of thousands of cycles
• System costs <150 €/ kWh (for a 100 kW system)

Many companies are developing grid-scale battery systems.

Water electrolysis is emerging as a compelling option for long-duration energy storage. Renewable electricity is stored in green hydrogen (H₂) fuel produced through water electrolysis. Hydrogen can be used as feedstock to produce other fuels via chemical processes:

1. Sabatier: synthesize methane from H₂ and CO₂
2. Haber-Bosch: synthesize green ammonia from clean H₂ and N₂
3. Fischer-Tropsch: produce alkanes from CO/CO₂ and H₂

However, compared to battery energy storage technologies, hydrogen storage systems (electrolysis + fuel cell) typically have a lower roundtrip efficiency of 30-45%. This means that a considerable portion of the initial energy input is lost during the storage and retrieval process:

• Electrolysis: Converting electricity to hydrogen (70-80% efficient)
• Compression and storage: Preparing hydrogen for storage (85-95% efficient)
• Fuel cell conversion: Converting hydrogen back to electricity (40-60% efficient)

Battolyser Systems has developed an innovative energy storage solution that combines a rechargeable battery and a water electrolyzer in a single, cost-effective device. This dual-purpose system, called a battolyser, uses nickel-iron alkaline battery technology and alkaline water electrolysis.

The battolyser operates in two modes:

1. Battery mode: Stores excess electricity from renewable sources when there's a surplus.
2. Electrolysis mode: Produces hydrogen through water electrolysis once the battery reaches maximum capacity.

This technology offers a flexible solution for managing intermittent renewable energy sources. It can charge and produce low-cost hydrogen when electricity prices are average or low, and discharge to sell electricity when prices are high.

Battolyser Systems’s battolyser

The diagram shows a battolyser stack developed by Battolyser Systems, consisting of multiple stacked battolyser cells.