How powder metal hydrides solve safety and size challenges for hydrogen storage
Global warming concerns linger and extreme weather events over the last decade have demonstrated the intensified need for a deeper commitment to proactive energy policies. Current CO2-intensive energy creations and energy supplies through public energy grids are not viable, long-term solutions.
New energy policies require global carbon footprint reductions over the next 20 years, with an ultimate objective of a CO2 -neutral infrastructure. To get there, innovative energy management concepts must be developed. This is where GKN Powder Metallurgy steps in: Our team has developed a safe, compact hydrogen storage solution for CO2 -neutral energy management systems by leveraging powder metal hydrides.
THE ROLE OF RENEWABLES AND HYDROGEN
Energy generated from solar, wind, hydropower and geothermal renewable sources are surging forward as contributors in achieving CO2 neutrality. Introducing large energy storage systems as safety buffers will solve the challenge of supporting these energy supplies, even despite fluctuations in regenerative energies.
What role does hydrogen play in storage system development? Hydrogen can be used as an energy carrier to store energy from renewable sources over a long-term period without generating any loss or pollution. Explained by the phrase ‘power-to-gas,’ excess energy from renewable sources is used to generate hydrogen by applying an electric current that divides water into hydrogen and oxygen – through a process called electrolysis - and is then stored. Later, this hydrogen can be converted back into energy.
In 2019, GKN Powder Metallurgy officially opened its hydrogen storage-based residential home that operates on the developed Hy2Green energy storage system. The system creates green energy from regenerative sources, stores it and provides electrical power and heat when needed – all in a local ecosystem with no emissions other than water and oxygen.
NEW ENERGY CONCEPTS AND NEW SAFETY ISSUES
Hydrogen is a non-toxic molecule in water and almost all organic compounds and is present in nearly all molecules in living things. There are two methods to leveraging hydrogen’s power: burning it without any residuals or re-converting it into electrical and thermal power with fuel cells.
Between varying fuel types, hydrogen has the highest energy density, 33.3 kWh/kg, almost three times that of gasoline. The challenge with hydrogen is that hydrogen atoms are light and its volumetric density is low. One cubic meter of hydrogen, at ambient temperate, is only equivalent to 0.34L of gasoline in terms of energy output. This means hydrogen gas normally needs to be compressed to be stored within a reasonable space. For mobility applications, the standard hydrogen pressures are up to 700 bars.
To withstand high pressure and keep vessel weight low, a carbon fiber-reinforced plastic material is typically used. High pressure rates bare the risk of leakage and, with the presence of an ignition source, potential explosions. Preventing these risks is one of the main challenges of high-pressure hydrogen storage solutions.
METAL HYDRIDES AS THE LOW-PRESSURE SOLUTION
As an alternative to high-pressure storage systems, metal hydrides are a safe and controllable technology to store hydrogen at lower pressures in small spaces. This low-pressure concept works because the hydrogen molecules are chemically bonded within the metal compound structure and remain stable and nonhazardous at atmospheric pressure. Metal hydride storage systems typically operate at 10-40 bars, which is twenty times less than typical high-pressure systems. Once the hydrogen is needed, the desorption process begins by feeding thermal heat (45 – 65°C) so gas begins to flow outward. At this stage, pressures are down to around one to two bars.
Conventional hydrogen storage tanks are large in size or are under high pressure, both of which are safety risks. GKN Powder Metallurgy's Hy2Green storage tanks put you on the safe side while effectively storing energy.
The storage capacity of the metal hydride storage is at 1.5kg - or 50 kWh energy - hydrogen per 100kg of the metal hydride compound material. As a comparison, this is close to the energy capacity of a standard Lithium Ion battery offered in a Tesla Model 3 vehicle.
The metal hydride storage technology is sustainable due to its material resources and is completely recyclable. High-pressure vessels made from carbon fiber-reinforced plastic are not 100 percent recyclable, and electrochemical electric battery storage systems lack recycling efforts while exhausting the resources for raw materials.
WHERE METAL HYDRIDE SYSTEMS CREATE BIG IMPACT
Metal hydride storage is ideal for situations where hydrogen is produced onsite from renewable electrolysis and is stored over extended periods. Once power is needed, it can instantly be recovered as hydrogen gas or in the form of electric or thermal energy when re-converted through a fuel cell.
Metal hydride storage combines the benefits of low-pressure tanks for safe operations with its high-power density capabilities. The technology excels in applications with high safety requirements and where CO2 emissions need to be reduced from coal or gasoline power generation.
The sizing of the metal hydride storage systems is determined by specification application need. GKN Powder Metallurgy covers the energy storage range from 80 kWh to 66MWh. A complete system requires equipment modules like electrolysis, fuel cells and other alternative equipment blocks. The system's modularity and integration capabilities enable a high level of flexibility.
Our current market projects and inquiries cover:
- UPS/back-up power systems for safety-critical infrastructures like radio stations, hospitals, and IT infrastructure
- Off-grid locations and ‘green’ buildings
- Alternative drives for maritime and heavy-duty mobility
The hydrogen infrastructure is still young and evolving. As industrialization continues and the need grows, cost and efficiency improvements for major technology equipment will follow.