Challenges of scaling hydrogen infrastructure
Hydrogen provides many benefits to industrial processes and is gaining popularity as a potential source of high efficiency, low emissions energy. The fuel cell industry in particular is seeing promise in clean hydrogen energy sources and is working to increase its viability in various applications, like the following:
In automotive applications, hydrogen and proton exchange membrane (PEM) fuel cells have been used to power fuel cell electric vehicles (FCEV) like the Toyota Mirai, which has quick refuel times and a larger driving range than competing battery-powered electric vehicles. For power infrastructure applications, large stationary fuel cell stack systems have been installed globally and are providing over 800 MW of power annually across the globe.
While the implementation of hydrogen as an energy source is yielding many positive results, it hasn’t yet reached its full potential. There are a few key challenges that must be overcome before hydrogen can be adopted as a widespread clean energy source, which we discuss here.
Hydrogen production: Environmental friendliness, cost-effectiveness, and quality control
Hydrogen production is appealing due to its potential to serve as a low emissions energy source, but an estimated 96% of hydrogen is generated globally through traditional fossil fuel processes involving natural gas, coal, and crude oil. Research and development efforts within the last decade have focused on increasing the viability of green hydrogen production processes that can instead be powered by renewable wind and solar energy, such as electrolysis.
The primary challenge is that it’s expensive to switch from standard energy production methods to environmentally friendly alternatives, although steps are being taken to increase the financial viability. The US Department of Energy is currently trying to lower hydrogen costs to less than $4/kg (for the end consumer). Their short term focus is on improving established industrial processes and electrolysis, and they want to eventually transition to biomass and solar based approaches.
Another challenge is the standardization of quality control. ISO 19880-8:2019, released less than two years ago, specifies the protocol to ensure H2 quality at distribution facilities and fueling stations. However, impurities are variable between hydrogen generation processes, and more information is still needed for these protocols to be completely relevant.
Hydrogen storage: Increasing capacity, durability, and efficiency
Storage of hydrogen is a key component of the hydrogen energy infrastructure and includes both long-term storage for future distribution as well as short-term storage for transport applications such as PEM FCEVs. Hydrogen can be stored as a gas in compressed high-pressure tanks (350-700 bar) or underground caverns, as a liquid cryogenically (-253°C boiling point at 1 atm), or as a solid within a variety of powdered materials. Storage methods for both long- and short-term face a set of significant scalability challenges.
Transport/portable applications face challenges in terms of fuel storage, as they need to be able to increase onboard fuel capacity to meet demands for greater driving ranges. And although gaseous hydrogen has almost 3x the energy of gasoline fuel (120 MJ/kg vs 44 MJ/kg), it is also 4x less dense (8 MJ/L vs 32 MJ/L) – so it is important to develop robust, lightweight compressed gas containers capable of withstanding high pressures and large enough to meet consumer needs.
The primary challenge faced by fuel cell stack applications is optimizing the volume, durability, leakage, and cost of the tank. While liquid hydrogen tanks can store more hydrogen per unit-volume, research needs to be done to minimize leakage and maximize container lifetime.
Most applications using hydrogen storage require that hydrogen leaks are accurately monitored and measured. This ensures the safety of users and allows for effective assessment and improvement of process efficiency.
Hydrogen distribution: Monitoring pipelines and increasing liquefaction efficiency
There are several ways to transport hydrogen, varying by application and distance. Chemical and industrial applications tend to use pipelines, which direct the hydrogen from production sources across relatively short distances to large users. The US currently has over 2500 km of H2 pipelines and the EU plans to have 6800 km by 2030 – and it can be challenging to monitor these long stretches of pipeline for leaks and damages.
Fuel cell applications require more direct transportation by truck to stationary stacks and fueling stations. One challenge is the extremely low density of hydrogen (≈0.09 g/L at 1 atm and 0°C). For perspective, one liquid gasoline truck can hold the same amount of energy as 19 trucks of gaseous hydrogen. Fortunately, hydrogen can be stored in its liquid form in cryogenic tankers, with one tanker capable of holding enough hydrogen to match the energy in one gasoline truck. But hydrogen liquefaction is energy intensive, so a challenge is finding new lower energy, cost effective ways to compress hydrogen.
Hydrogen end-use: Increasing efficiency while decreasing cost
Hydrogen doesn’t always go directly into end-use applications – but in PEM FCEV applications, hydrogen is dispensed directly at refueling stations. The primary challenges at this stage are still to increase efficiency and to decrease cost. FCEVs face fierce competition from electric vehicles, and while they have faster fueling times and greater driving range capabilities, they need further optimization so that demand will increase and more refueling stations can be established.
Alicat Scientific supports the hydrogen fuel cell industry by selling mass flow instruments to several customers for fuel cell stack development applications. Accurate and precise measurement and control of fluids are critical for many processes, from leak checking hydrogen in fuel cells to flowing DI water for electrolysis.