Decarbonization and sustainability programs are happening in nearly every process, company and industry around the world. And this change continues to accelerate—whether due to financial incentives to do more with less, growing environmental regulations or pressure from customers.
Although there are many tiers of responses to this challenge, most often they involve removing the combustion of hydrocarbons. Some businesses are looking to electrification to become sustainable, relying on battery technologies to meet their energy storage demands.
What is not discussed as much is the interest in hydrogen as a replacement fuel.
The hydrogen atom is the most common substance in the universe and provides many advantages over fossil fuels used today for aerospace, energy generation and industrial processes. When used in fuel cells, the only emission is water vapor from the hydrogen reattaching with oxygen from the atmosphere. Hydrogen also has the highest specific energy of any non-nuclear power source, burning hotter and more efficiently than any of the alternative fuels. It can even be used as a direct replacement in some processes with minimal retrofitting. All of this is possible from a fuel that can be made from water and electricity. Unfortunately, deploying it at scale comes with challenges. Hydrogen could revolutionize our energy systems, but before that happens, engineers will need the best digital tools to remove the roadblocks.
There Are Still Challenges
Challenge number one in deploying hydrogen for energy storage is meeting the scale required to manufacture hydrogen sustainably. While hydrogen can be produced through many different processes, the only green option is doing so via electrolysis – splitting hydrogen off from oxygen by running a current through water. The most common process today is to use steam methane reformation, using natural gas as the feedstock, but the carbon emissions negate the benefits of using hydrogen in the first place. Green hydrogen will require a massive increase in electrolysis facilities and an abundance of renewable energy to power the process.
With a stable supply of green hydrogen, using it effectively is still a major challenge. It is an incredibly flammable gas, the element with the smallest atomic radius, and storing it at pressure will embrittle the storage tank if not properly designed. Deploying hydrogen at the scale to make an impact will require building out infrastructure and logistics networks to properly transport the fuel where it is needed most.
Either of these challenges would be enough on their own, but hydrogen as energy storage also suffers the early adopter tax. There are few applications today that can effectively use the fuel and those that can are met with high costs from the complexity of manufacture and delivery. The simple solution is to create a larger market for hydrogen on the demand side of the equation, and many companies have released products doing so, but getting there will require complex engineering with comprehensive digital tools.
Promising Applications for Hydrogen
The market for hydrogen is entirely dependent on the applications for it as a replacement fuel, an energy storage medium and as a part of a global commodity. Hydrogen production will not scale without a clear and present need from product demand. Fortunately, there are more than a handful of technologies, products, and processes set to create that need.
1. Energy generation and storage
Possibly the furthest along in deploying hydrogen as an energy source is the energy industry. Our sister company, Siemens Energy, is already manufacturing and selling grid-scale flexible-fuel gas turbines. These massive turbines are an iteration of their designs for natural gas (methane) combustion but can be switched to hydrogen as the feedstock with minimal retrofitting. This capability makes the turbines valuable during the shift to hydrogen and more sustainable energy. Utilities can purchase equipment today that will still be operational in the coming years when it is more effective to run on hydrogen.
These devices will also act as a learning opportunity to further characterize the physics of hydrogen combustion. We have had many years to understand the intricacies on methane combustion. To reach that level of understanding with hydrogen quickly, we will need the power of the digital twin to design, simulate and validate the best hydrogen-specific turbines. We already know that hydrogen burns hotter and can embrittle metals similar to oxidation reactions, but the impact of these properties on the internals of a multi-ton turbine spinning at a high number of rotations per minute is not entirely clear. Hydrogen will likely wear parts more rapidly, but how rapidly is an important answer to have, as well as how to avoid it altogether.
The perceived demand for future hydrogen is driving innovation across the energy sector. Existing natural gas facilities are investigating subsurface steam reformation processes that leave CO2 byproducts in the reservoir. And with the emergence of small modular nuclear reactors, using nuclear energy to produce a stable supply of hydrogen fuel is another growing conversation among energy companies. Hydrogen as storage for renewables and as fuel derived from sustainable sourcing is driving change in the energy supply chain.
For long-haul aircraft, long-range ground vehicles and marine vessels, the benefits of hydrogen over traditional fossil fuels and even battery electrification are great. Transportation in remote environments will be an important application of hydrogen as an energy source, but it will require more infrastructural improvements to get moving. There will be some design decisions early on because there are two competing technologies to release the chemical energy potential from hydrogen – combustion and fuel cells. Combustion releases far more energy than fuel cells per kilogram of hydrogen, but the amount of heat generated in this method can go to waste.
A car design may opt for fuel cell technologies to power electric motors, while an aircraft may choose combustion because it can harness more energy with jet engines. Implementing hydrogen in transportation will be application-specific.. Transportation networks are far less centralized than energy generation applications, by design. Some applications will be easier with smaller networks. Aircraft have very few paths relative to automobiles, which could make it a great test-case for the hydrogen transition if the big questions can be answered. Combustion or fuel-cell? How to store the fuel? And what shape will the product take?
3. Industrial Processes
The third, and possibly most disparate, application of hydrogen in decarbonization and sustainable business practices is with industrial processes. Many modern manufacturing processes require high-temperature phases. Traditionally this is achieved by burning fossil fuels, but as the world decarbonizes, new solutions are needed. Some metal smelting and high temperature processes can be done with electricity, but the efficiency of the resistive heaters in these solutions is too low for the energy required. As with gas turbines, hydrogen can be a replacement fuel, but just like transportation networks the number of facilities that will need access to the hydrogen will be too great for today’s infrastructure.
There are also far greater development needs to make some of these processes carbon neutral than solely switching fuels. Traditional cement manufacturing, for example, emits carbon dioxide in two distinct phases – first is during the firing stage in the cement kiln to create the clinker (a major portion of cement mixtures), from the burned fossil fuel. The second phase, which is not solved by using hydrogen, is that when breaking down the limestone into clinker, carbon dioxide and other gases are released. While this is not an impossible problem to solve on the path to decarbonization, it will require extra thought and engineering work to limit carbon emissions.
Scaling the best solutions
Scale is everything if hydrogen is going to take off as an alternative energy stream. It determines not just the availability of the fuel to deploy it in new products and technologies, but it also creates the cost incentive for more businesses to switch. A flex-fuel turbine can use hydrogen, but unless it is more profitable, there is little incentive to do so for a business. Once some scale is achieved, businesses deploying hydrogen will have the incentive to make consumption more efficient, just like business decisions today in respect to energy and material costs.
Eryn Devola is vice president of sustainability for Siemens Digital Industries, where she leads the Sustainability horizontal market to manage the strategy for profitable sustainability for Siemens and our customers.
Main photo: Flexible fuel turbines reduce material needs when it is time to transition to hydrogen.