Hydrogen: The Most Versatile Fuel for the Future of Clean Energy
Introduction
Hydrogen is the most abundant element in the universe. It is the first element on the periodic table and the building block for much of the matter that surrounds us here on Earth — think of all the H2O that covers 71% of the earth’s surface. In the energy sector, the hydrogen element has been intertwined with just about every major combustible fuel source in the form of hydrocarbons. Petroleum is made up of hydrogen and carbon atoms. Natural gas is made up of hydrogen and carbon. Even coal, which is mostly carbon, has small amounts of hydrogen in it. Of course, the problem with these legacy energy sources is the vast amounts of carbon-based greenhouse gases (GHGs) they emit when burned, leading to our world’s existential threat of climate change.
The hydrogen element seems to be synonymous with energy, so what if we could harness its power without generating toxic emissions? Enter the purest form of a hydrogen-based fuel: hydrogen gas/H2/hydrogen. When hydrogen (H2) is burned or used in a fuel cell, it combines with oxygen to produce water vapor as the only byproduct. Using hydrogen as a fuel circumvents the problematic GHG emissions of carbon dioxide (CO2) and methane. Even more impressively, hydrogen can produce more energy per kg than any other nonnuclear fuel source known to man — hydrogen can produce approximately 3x as much energy per kg as gasoline.
Hydrogen will have an important role to play in the future of clean energy. Our energy sector is complex, with different industries requiring different end-uses for energy, infrastructure, demand timing, and storage requirements, among other factors. Due to this variety of needs, there are certain industries where hydrogen can provide distinct value over other clean alternatives. I predict that hydrogen technology will become the dominant means of decarbonizing the following sectors: heavy-duty transportation, aviation, industrial heat, commercial & residential heat, and long-term energy storage.
How we produce hydrogen
Hydrogen doesn’t occur naturally the same way oil and natural gas do. While that’s okay because harvesting natural resources for fuel is inherently unsustainable, this does mean resources and energy need to go into producing hydrogen. A shocking and unfortunate reality about the current state of the hydrogen industry is that 98% of our world’s hydrogen supply comes from fossil fuels. This method, coined “grey hydrogen” production, most commonly sources hydrogen from methane (CH4) and releases CO2 into the atmosphere as part of the process. In fact, grey hydrogen production emits 830 million metric tons of CO2 every year, which translates to 2% of total global emissions. Grey hydrogen dominates the industry today because of its low cost. However, methods for producing hydrogen without CO2 emissions are evolving and growing in use.
The primary means for producing “green hydrogen” (hydrogen produced without emitting CO2) is electrolysis. Electrolysis is a renewable process in which electricity is used to split H2O into hydrogen and oxygen. The challenges with electrolysis today are its high costs and its need for a 100% clean electricity source. The US electric grid is only about 40% clean today. However, companies can choose to power their electrolyzers on 100% renewable sources with the right planning.
In addition to electrolysis, new innovative methods for green hydrogen production are being developed to help decarbonize the industry. A company I co-founded called Hydrova is developing one of these methods. The falling cost of electrolysis in combination with the commercialization of new methods like Hydrova’s will lead to an abundant clean supply of hydrogen gas in the future. This green hydrogen advancement will unlock the many opportunities for hydrogen to realize its full clean energy potential.
The status of hydrogen today
While hydrogen has many exciting clean energy applications on the road ahead, it is also used in a large capacity in mature industrial markets. Hydrogen is used in oil refining, ammonia production, methanol production, metal processing, and various other chemical and industrial applications. 95% of hydrogen produced today is used as a chemical feedstock or reactant in these chemical/industrial processes. These processes consume 11.4 million metric tons of hydrogen per year in the US, and contribute to a $117.5 billion global hydrogen generation market.
Springboarding off of its mature use in chemical and industrial markets, hydrogen is beginning to penetrate the energy sector at a rapid rate. As an example of this growth, the market for hydrogen fuel cell vehicles has a 66.9% compound annual growth rate (CAGR). Fuel cell passenger cars only scratch the surface, though, of the possibilities for hydrogen. Hydrogen can offer an alternative approach to electrification in terms of how we decarbonize many different hard-to-electrify sectors.
This introduces a critical differentiator of hydrogen as an energy-carrying molecule in comparison to an electricity-generating source such as solar and wind. Solar PV cells and wind turbines harness renewable energy and create electrons as an output. Those electrons are a valuable currency for creating the residential and commercial conveniences we’re accustomed to today — like powering appliances and lighting. However, electrons can’t power everything. In fact, the electricity sector only accounts for 17% of total energy consumption per year. Meanwhile, transportation accounts for 37% of energy consumption, and industry accounts for 35%. These two sectors today primarily don’t use electrons as their energy currency; they instead use combustible fuels like petroleum or natural gas. Contrasting with electricity, hydrogen is an energy currency that comes in the form of a molecule (much like petroleum or natural gas). On top of that, hydrogen has much more versatility in how its energy can be unleashed. Hydrogen can be combusted to produce heat, can be used as a chemical feedstock to produce other valuable molecules/fuels, and yes, can even produce electricity via a fuel cell. This versatility in energy use is what makes hydrogen valuable in a wider umbrella of energy markets and is why hydrogen is set to revolutionize our world’s energy sector.
Sectors like transportation and industry already use combustible fuels today, and converting these sectors to be electron-powered would introduce massive infrastructural challenges. For these reasons, hydrogen can provide a great “drop-in” solution that makes the decarbonization transition easy. In transport, the majority of vehicles used for road, rail, air, or water transportation today burn fossil fuels on board to create their power. In the industrial sector, large amounts of emissions are generated from the combustion of fuels to create high heats. Take cement production, for example — a single product that alone creates 8% of our world’s emissions. These emissions largely come from burning fossil fuels to generate the 1,450°C temperatures necessary to produce clinker (the main constituent of cement). What if we had an energy-dense, zero emissions, combustible fuel that could replace the carbon-emitting fuels we use to power transportation and industry today? Hydrogen can do just that.
Where hydrogen can create the most value
1. Heavy Duty Transport
Transportation is currently responsible for 27% of GHG emissions in the US due largely to the prevalence of the internal combustion engine (ICE). Road transport is responsible for 71% of our world’s transportation industry energy usage, so cleaning up the vehicles we have on the road is paramount. Luckily for the environment, battery-powered electric vehicles (BEVs) and hydrogen-powered fuel cell electric vehicles (FCEVs) are two zero-emissions solutions that are on the market and gaining traction. For passenger cars, BEVs have been around for a little over 12 years and already gained nearly 2% of market share in the US. And in Norway, BEVs already have an astounding 30% market share. FCEVs had a later entry to the market (beginning about 4 years ago), but are now growing in sales at a rapid rate. In the US, over 7,600 FCEVs are on the road already — most of which are in California since the state has the largest refueling station network. Though the FCEV market is young, the technology has some key advantages in that refueling a FCEV with hydrogen gas only takes about 5 minutes (compared to hours for a BEV) and FCEVs have superior range.
When it comes to heavy-duty transportation vehicles like buses and trucks, FCEVs have an unfair advantage, which will likely make them dominate this sector in a decarbonized economy. BEV range constraints and long recharging times are greatly magnified when the vehicle is as large as a bus/truck. Moreover, the companies and governments that operate these vehicles rely on high-utilization of their fleets. Every hour a truck is idle is an operational expense. Thus being able to quickly refuel is key and is something in which hydrogen blows battery recharging out of the water. For example, while a BEV truck will require 1 hour and 10 minutes to recharge its batteries for just 120 miles worth of range, a FCEV hydrogen truck will be able to refuel 500–750 miles worth of range in just 20 minutes. That compounds to hydrogen trucks requiring as little as 1/22 the time electric trucks spend on refueling, increasing utilization and range dramatically. Furthermore, hydrogen can be deployed to trucks and buses as a fuel, the exact same way diesel is. Meanwhile, recharging electric trucks would introduce infrastructural shock. Aurora Energy Research found that recharging a Tesla Semi would be the equivalent of 4,000 new homes hitting the grid at once. This would be an enormous stress to existing grid infrastructure. Refueling trucks via hydrogen as a molecule circumvents this challenge.
Fuel cell bus fleets are just beginning to roll out internationally with 83 buses in operation in Europe, 44 in North America, and 100 in Japan. Gaining millions of miles of operational experience, these hydrogen-powered buses are building the foundation for a future hydrogen-driven public transport industry. China recognizes this future and announced in 2019 that they are cutting subsidies for BEVs in order to allocate more investment towards FCEVs. China’s goal now is to have 1 million FCEVs on the road by 2030. Multiple municipalities in California (including San Francisco, Irvine, and Orange County) have invested in their first fuel cell buses for public transport, which are on the road today. Additionally, large corporations like FedEx and Ryder are investing in heavy-duty FCEVs. Hiringa Energy recently placed an order of 1,500 fuel cell trucks from Hyzon Motors, an American FCEV manufacturer. Hyundai is manufacturing a fuel cell truck (the Xcient) and delivered its first units in late 2020, which are now on the road in Europe. Many other large vehicle manufacturers, including Toyota, GM, and Navistar are investing heavily in building fuel cell trucks. The FCEV market is in its infancy but is on the verge of a boom due to hydrogen’s unfair advantages as a heavy-duty transportation fuel.
2. Aviation
The aviation sector is responsible for 12% of global transportation energy usage. The International Civil Aviation Organization is taking action by capping global aviation emissions at 2020 levels. To fulfill this commitment, significant advancements in lower/zero-emissions aviation propulsion need to be made. Currently, our options appear to be battery/hybrid power, biofuels/synthetic fuels, and hydrogen. Battery electric aircrafts have many hurdles to overcome. The obstacle boils down to energy density and the difficulty of packing as much electrical potential as possible into a finite amount of space, while not substantially weighing the plane down with batteries. On the biofuels front, the FAA has played a significant role in developing, testing, and commercially approving jet fuels made of everything from sugars to municipal waste to agricultural waste. The challenge with these fuels, however, is that they’re lower emissions but not emissions-free.
Liquid hydrogen offers an emissions-free alternative that doesn’t suffer from the same weight challenges as batteries. As the most gravimetrically energy-dense fuel known to man, liquid hydrogen can generate the same amount of energy as kerosene jet fuel with ⅓ the weight. However, as a less volumetrically energy-dense fuel, liquid hydrogen requires 4 times the space as kerosene for the same amount of energy. For this reason, airplanes must be redesigned to accommodate greater fuel storage space. Luckily, this is a surmountable challenge. A team of British engineers has proposed two potential passenger aircraft designs to account for the greater space and low temperatures liquid hydrogen requires. Additionally, Airbus recently announced designs for three future passenger aircrafts that run on hydrogen. They aim to bring these aircrafts to market by 2035. This announcement from one of the two major global aircraft manufacturers sends a powerful message about the important role hydrogen will play in the future of aviation. And this isn’t just a future vision. A startup called ZeroAvia has already completed successful test flights of its zero-emissions, hydrogen-powered aircraft, which it plans on offering commercially in 2023.
The consensus among experts is that hydrogen is our only hope when it comes to decarbonizing aviation. Paul Eremenko, the former CTO of Airbus, stated that “hydrogen is the only viable path for aviation to reach Paris Agreement targets and help limit global warming.” Paul left Airbus to start a company called Universal Hydrogen, which recently raised a $20.5M Series A to develop hydrogen storage solutions and conversion kits for commercial aircraft. The company plans to bring its solution to market by 2025.
3. Industrial Heat
Industry accounts for 22% of GHG emissions in the US. These emissions mostly come from the high-temperature heat needed to fuel industrial processes like aforementioned cement production. Coal and natural gas dominate industrial heating today due to their low cost. These combustible fuel sources also allow heat to be generated on-demand and quickly ramped up and down. For this reason, industry is considered to be a sector that can’t easily be decarbonized via electrification. Thus, hydrogen might be our best hope for decarbonizing industry because it can be combusted on demand to produce high heats in the same way coal and natural gas can. Because of hydrogen’s similarities to natural gas especially, existing infrastructure could be modified to function with hydrogen, avoiding massive new capital expenditures. The Rocky Mountain Institute, a long-standing thought leader in clean energy research, sees hydrogen as the only viable pathway to decarbonizing industrial heat.
To transition such a massive sector from fossil fuels to hydrogen, demonstration projects and cost improvements will be critical. Earlier this year in Sweden, steel smelting was successfully fueled by hydrogen heat for the first time on a commercial scale. Steel production is traditionally fueled by coal or natural gas, so achieving this same process by substituting in hydrogen is a major milestone. In the US, a steel plant technology firm called Midrex is pioneering direct reduction of iron ore using hydrogen and aims to help major US steel producers like Nucor make the transition. With water vapor as its only byproduct, hydrogen provides a sustainable and efficient heat source that could very well fuel steel production and other industrial applications in the future.
4. Commercial and Residential Heating
Commercial and residential settings require heat as well. The temperatures are lower than those used in an industrial setting, however, the challenge remains the same with emissions deriving from our current use of fossil fuels. In 2018, the overall commercial and residential sectors accounted for 12% of greenhouse gas emissions, with the majority of those coming from heating. One way we can decarbonize this sector is by electrifying appliances that traditionally use gas. While this is feasible and a powerful tool for new homes and buildings, we need to decarbonize existing homes and buildings as well that rely on the gas grid for heating. Hydrogen will play a critical role in accomplishing this. Industry experts have identified three key strategies in which hydrogen can support this decarbonization transition. 1) We can blend hydrogen with natural gas to supply the gas grid with little infrastructural change required 2) We can upgrade gas pipeline infrastructure in order to transfer to a gas grid made up of 100% hydrogen. 3) we can produce synthetic natural gas using hydrogen in combination with captured CO2. These strategies can be introduced in phases to ease the transition. Scotland recently announced it will be doing just that, outlining a strategy to blend hydrogen into the gas grid by 2030 and then transition to a 100% hydrogen gas grid by 2050.
5. Long Term Energy Storage
As the deployment of renewables like solar and wind expands, energy storage is becoming increasingly critical to balance supply and demand. Hydrogen can be an excellent medium for storing energy. In peak solar and wind hours, surplus electricity can be run through electrolyzers to generate green hydrogen. That hydrogen can be stored and then run through a fuel cell to generate electricity when there is high demand but low solar and wind generation. Hydrogen energy storage doesn’t rely on finite geographical resources as pumped hydro does. It also doesn’t discharge over time in the same way electrochemical batteries like lithium-ion do; since hydrogen is a molecular energy carrier, its energy potential can essentially be stored indefinitely with the right storage conditions. This makes hydrogen uniquely powerful in long-duration energy storage and even seasonal energy storage. Hydrogen can additionally be stored in more volumetrically dense substances like liquid hydrogen or ammonia to save space.
Large hydrogen energy storage projects are being developed globally. The Advanced Clean Energy Storage (ACES) project in Utah is one example, in which up to 1,000 megawatts of clean power storage will be available via electrolysis. To handle the subsequent massive volume of hydrogen, ACES will make use of an underground geological formation called a salt dome. Salt domes have already long been used for storing large quantities of liquid fuel, which means hydrogen can springboard off of existing infrastructure. The ACES facility will initially be capable of powering 150,000 households for one year and is scheduled to be in operation by 2025. Hydrogen storage in salt caverns is being investigated in many European countries as well. Researchers in Germany found that Europe has enough salt caverns to handle a hydrogen storage capacity of up to 84.8 PWh. The unique spatial solution of salt caverns just goes to show that the benefits of hydrogen power storage can scale to the level we would need in a 100% renewable electricity grid.
Challenges of hydrogen
As is the case with any burgeoning clean energy technology, there are some overarching challenges facing hydrogen, which are important to address. First, it is too expensive to produce cleanly right now. Producing hydrogen via electrolysis today is 3 to 5 times as expensive as doing so via steam methane reforming (the dominant fossil fuel method). Cost-effective production of green hydrogen will be paramount for the industry. New method innovations, like Hydrova’s, and economies of scale for electrolyzer manufacturing will help realize this necessity. If we see the same type of investment in green hydrogen as we saw in solar and wind over the last decade, we’re going to see a similarly successful outcome where green hydrogen becomes more economical than grey hydrogen. We will likely also see hydrogen become market competitive with fuels like natural gas and petroleum (on an energy output per cost basis). Industry experts project electrolysis could become cost-competitive with grey hydrogen as soon as 2030.
Another overarching challenge for hydrogen is its volumetric energy density. Even when stored as a liquid, hydrogen requires about 4 times as much volumetric space as an equivalent energy supply of gasoline. This introduces greater engineering challenges when the amount of space in an application is limited. However, this barrier is not insurmountable as we’ve seen with the achievable design of a hydrogen-powered aircraft.
Additionally, the success of hydrogen vehicles faces a major obstacle with refueling infrastructure. Internal combustion engine vehicles have become and remain ubiquitous because of the hundreds of thousands of gas stations that fuel them. To make FCEVs as convenient to operate as ICEs, an extensive network of hydrogen refueling stations will need to be developed. This presents a dilemma since consumers will not want to purchase FCEVs if they can’t easily refuel them yet; however, a company will be equally unlikely to create a hydrogen fueling station if it doesn’t believe the FCEV customers exist yet. This is a dilemma that needs to be overcome in order to realize the benefits of FCEV technology. California has been able to begin to overcome this challenge by introducing government subsidies on both the vehicle and fueling station sides. More states and the federal government will need to take similar action to catalyze this progress.
Conclusion
Hydrogen is an incredibly powerful and versatile tool for combating climate change. With the ability to be combusted to produce heat, synthesized to produce other valuable molecules, and run through a fuel cell to generate electricity, hydrogen is uniquely suited to decarbonize some of the world’s highest emitting sectors. There is no doubt that hydrogen will have a role to play in powering the future of heavy-duty transport, aviation, industrial heating, residential and commercial heating, and long-term energy storage. As more is learned about its potential, hydrogen’s applications will only expand from there. The future looks bright for the hydrogen industry, and that makes our climate’s future look bright as well.
