Special Focus: Fuel Cell Applications

N. LAWRENCE, Ceres, Horsham, England

While many fuel cell variants have been developed, their commercialization still faces challenges despite the technology’s clear potential. Intermediate temperature, steel-supported solid oxide technology is a potential game-changer for fuel cell and electrolyzer applications.

Developers of this technology aim to overcome the barriers that have hindered the advancement of the hydrogen (H₂) industry to date and deliver the efficiency, robustness and longevity needed to make it an affordable alternative for clean energy and H₂ production.   

This reversible technology has the potential to efficiently generate green H₂ to decarbonize heavy industry (e.g., fertilizers, eFuels, steel making) and provide clean energy to alleviate grid constraints, enabling scale and maintaining pace with the growth of data centers and manufacturing.

Global demand. The global push for electrification is accelerating—consumption is predicted to at least double by 2050. Electricity will be the largest source of energy by 2050, with increased consumption coming from traditional sectors (e.g., buildings) and newer sectors like data centers, electric vehicles and green H₂.

The digital economy's expansion has led to an unprecedented growth in data centers, which are the backbone of cloud computing, data storage and online services. These facilities consume vast quantities of electricity to power servers, support data processing and maintain optimal operating conditions through cooling systems. In the race for artificial intelligence (AI) supremacy, waiting for power and grid connections is a prohibitive factor. 

The combined impact of these trends is placing greater pressure on energy infrastructure to meet the rising electricity demand. This has implications for energy generation, distribution and the need for sustainable and renewable energy sources to ensure a reliable and environmentally friendly electricity supply. 

A similar picture is emerging around the use of H₂ for industrial decarbonization. While H₂ was viewed 20 yr ago only as a contender for automotive transportation, its use in heavy industrial applications is set to accelerate. Between 2030 and 2050, the use of H₂ is expected to double each decade as its applications expand across steel, chemicals, cement and large-scale manufacturing.

It should be noted that even existing use-cases for H₂ present a major decarbonization challenge and a large opportunity, with the  forecast 100–MMtpy demand requiring approximately 450 gigawatts (GW)–600 GW of electrolyzer capacity, depending on the technology chosen (FIG. 1).

Types of cell technology. The development of fuel cells and electrolyzers has separated into three distinct channels—proton exchange membrane (PEM), alkaline and solid oxide—since the modern era of research began in the 1960s. Each presents its own advantages and suitability for different applications. The development of each type of cell involves trade-offs between operational efficiency, lifetime and cost. 

Low-temperature fuel cell technologies tend to suffer from slow reaction rates and poor conductivity. They usually require expensive and specialist catalysts to operate efficiently and high-purity fuels to prevent these catalysts from being poisoned. Heat also must be removed from these cells to maintain low temperatures, further impacting efficiency. However, low-temperature fuel cells are robust, and can be cycled easily. 

High-temperature fuel cells operate far more efficiently because reaction rates are higher, materials conduct better and all catalysts work more efficiently. Gases also diffuse and move more easily, and system losses are much lower. These high temperatures, however, come at a price: expensive and sometimes exotic high-temperature materials are required, such as ceramics, which can be fragile and difficult to cycle.

The long-sought-after “goldilocks” (one-size-fits-all) solution is a cell that operates at moderate temperatures, with high efficiency, requires no expensive catalysts, and has good longevity and low build costs as specialist materials are not required.   

PEM cells. In fuel cell mode, PEM cells have the advantage of quick startup times and responsiveness to load changes. They are also relatively compact via high-power density and operate at relatively low temperatures of around 80°C (176°F). These attributes have made them a popular option for H₂-powered road vehicles, and PEM cells have been adopted by major automotive companies such as Toyota, Hyundai and Honda.   

The limiting factors are cost related, due to the need for expensive catalysts, usually platinum. This also introduces the risk of catalyst contamination where the performance is degraded by the trace presence of sulfur dioxide (SO₂), ammonia (NH₃), hydrogen sulfide (H₂S) or hydrocarbons in the H₂. This necessitates the need for ultra-high-purity H₂, typically > 99.999% pure, which is extremely expensive.  

Regarding H₂ production (electrolysis), PEM cells are known for high-purity production and dynamic response to demand at low-temperature operation, but also suffer the same requirement for high-purity feedstock and expensive catalysts.

Alkaline. The alkaline fuel cell is probably most famous for its role in power generation for the NASA (U.S.) Apollo space missions and shuttles. It has proven reliable in operation, and the fact that it does not require expensive catalysts, high-temperature operation or high-purity H₂ has made it popular for some applications.  

The main limitations, for both fuel cell and H₂ production applications, come from the highly corrosive liquid electrolyte that is inherent in the cell design, which leads to maintenance and operational challenges. It is also slower to react to dynamic load applications compared to other technologies.   

High-temperature solid oxide. Research into solid oxide cells pre-dates both PEM and alkaline technologies, but it has been the latest fuel cell and electrolyzer technology to be commercialized. Traditionally, solid oxide fuel cells (SOFCs) have required high operating temperatures of 800°C–1,000°C (1,472°F–1,832°F) that proved challenging to engineer due to the specialized components needed to combat material degradation and shorter lifespans because of thermal cycling. High temperatures also necessitated longer startup times and required complex thermal management and insulation.   

However, the benefits were substantial. SOFCs are capable of surpassing 60% in electricity generation and up to 90% in heat and power co-generation. They also provide fuel selection flexibility and enable natural gas, biogas, H₂ and other future fuels to be used.

There is no shortage of natural gas in the world, but there is a clear determination to stop its combustion in turbines. SOFCs could enable natural gas to continue to be used as a major global fuel, but now in a clean way with efficient carbon capture of the concentrated stream of carbon dioxide (CO₂) from the SOFC system.

These high efficiencies also apply when solid oxide is used in electrolyzer cells (SOECs), especially when integrated with waste heat from an industrial process.

The intermediate temperature “goldilocks” solution. The author’s company’s variant on traditional solid oxide technology^a uses a compound of ceria in the electrolyte to dramatically cut the cell temperature to just 450°C–630°C (842°F–1,166°F), without compromising efficiency or fuel flexibility. 

Equally applied to SOFC and SOEC applications, this reduced operating temperature means the chemistry can be printed onto a steel substrate, providing superior mechanical strength compared to ceramic cells. Additionally, commodity steels and seals can be used in the stack’s construction, further improving robustness, tolerance to vibration and cost. 

First pioneered by research groups at Imperial College in London, England, the company now licenses its technology in a series of products that are being brought to market by some of the world’s largest industrial companies, including Doosan (South Korea), Denso (Japan), Thermax (India) and Delta (Taiwan). 

These large-scale manufacturers promise to not only bring the benefits of SOFCs and SOECsa to the world, but substantially reduce costs further through efficiencies in manufacturing.

Powering the energy transition. The rise in the use of fuel cells and electrolyzers has important ramifications for the global energy transition and reducing the rate of climate change. 

SOFCs provide an efficient and robust means to generate electricity for data centers and microgrid applications from natural gas, bio-methane and many future fuels, ensuring the world can meet the energy challenges of AI and growth in domestic demand. Shipping and static power could also be converted to clean generation to cut greenhouse gasses and diesel particulates that pollute our atmosphere.  

SOECs have the potential to radically change our industrial landscape using green H₂ in fertilizer production, steel manufacturing and other industrial applications. 

Takeaway. The importance of SOFC and SOEC technology is not only its clean credentials, but also the fact that it can deliver energy resilience, energy sustainability and energy security. Countries that are major importers of energy have weathered worrying perturbations in supply and extreme volatility in cost in recent years. The introduction of a robust technology that can be used for the industrial production of H₂ and the generation of electrical power with H₂ is an extremely attractive proposition. H₂T 

About the author

NICK LAWRENCE is the Chief Product Officer at Ceres. He joined the company in 2016 and has since been a driving force behind the acceleration of Ceres’ ambition to become a world leader in solid oxide technology.

Lawrence has experience across several technology disciplines, including engineering, digitalization, modelling and AI. As a member of Ceres’ Executive Team, he leads the company’s talented product organization in delivering best-in-class products for current and future partners. Lawrence is a chartered engineer, a member of the Institution of Mechanical Engineers and holds an MS degree in engineering science from the University of Oxford.

Note 

^a Ceres SteelCell^®