What does it take to make low-emission hydrogen and ammonia?
Today, 80% of global final energy demand is met by unabated fossil fuels, which release carbon dioxide and other harmful pollutants into the atmosphere when burned. Electrification and the expansion of clean electricity will play a critical role in decarbonizing most of this demand, but the remaining hard-to-electrify industries, including steel manufacturing, petrochemicals and marine shipping, will need zero-carbon substitutes to reach full decarbonization.
In these cases, zero-carbon fuels like low-emissions hydrogen or ammonia, which contain no carbon and produce no carbon dioxide when combusted or used in a fuel cell, can play a valuable role in decarbonizing the global economy.
Today’s industry already uses hydrogen for fertilizer, chemical, and conventional fuel production. In fact, the U.S. and European Union (EU) currently produce 10 million tonnes per annum (TPA) of hydrogen respectively for these purposes. The problem? The industry isn’t generating this hydrogen in a climate beneficial way. Today’s hydrogen mostly comes from reacting natural gas with steam, a process known as steam methane reforming, and is responsible for more than 900 million tonnes of carbon emissions per year. This makes switching to low-emission production methods a top priority. We can do this by ensuring steam methane reforming uses carbon capture and storage (often referred to as ‘blue’ hydrogen) or by using low-carbon electricity to split water into hydrogen and oxygen, a process known as electrolysis (also often referred to as ‘green’ hydrogen).
Many governments have recognized this need for more low-emissions hydrogen and have announced plans to rapidly scale production. In the U.S., the Department of Energy (DOE) aims to increase low-emissions hydrogen production from nearly zero today to 10 million tonnes per annum (TPA) by 2030. The EU has announced even more aggressive targets, planning to produce 10 million TPA of hydrogen domestically and import 10 million TPA of renewable hydrogen by 2030.
But while recognition of the decarbonization potential that low-emissions hydrogen offers is on the rise, the material requirements of low-emissions hydrogen production, whether through electrolysis or steam methane reforming with carbon capture, are less broadly understood. That is why CATF created the Hydrogen Production Calculator, an interactive tool that gives users a better understanding of the quantities of natural gas, water, and electricity required to produce different amounts of hydrogen, as well as the by-products from these processes. Just plug in your desired amount of hydrogen, and the calculator will present the resource quantities that you will need.
So, what goes into producing a given amount of low-emissions hydrogen? To help answer this question, we put our calculator to work, below:
Hydrogen Produced with Natural Gas and Carbon Capture (‘Blue’ Hydrogen)
A typical steam methane reformer — without carbon capture — produces around 10,000 kilograms per hour (kg/hr) of hydrogen. If we input this production amount into the calculator, we see that a similarly sized steam methane reformer with carbon capture would consume 1800 MMBTU (530 MWh) of natural gas per hour, which is around what 230,000 U.S homes consume in an hour.1 The plant would also consume around 200 gallons of water per minute, which is around what 1000 U.S. homes consume each minute.2
Hydrogen Produced from Electrolysis with Renewable Electricity (‘Green’ Hydrogen)
If we input the 10,000 kg/hr of hydrogen produced by a typical steam methane reformer, we find that a similarly sized electrolysis plant would consume 530 MWh of electricity each hour — or around what 440,000 U.S. homes consume in an hour.3 The electrolysis plant would also consume 440 gallons of water per minute, which is around what 2,100 U.S. homes consume each minute.2
Whether using steam methane reforming with carbon capture or electrolysis, producing hydrogen will be a resource-intensive enterprise. This insight becomes even more important as we consider the scale of inputs required to meet the world’s low emissions hydrogen demand.
Meeting DOE’s target of 10 million TPA, for example, solely through hydrogen produced with renewable energy would require at least 60 GW of low-carbon electricity and electrolyzer capacity — this number is significantly higher if the source of clean electricity is variable in nature (e.g. solar, wind). To put this into perspective, the U.S. installed 24.5 GW of new solar and wind in 2020. This was higher in 2021 at 28.7 GW.
The scenario described above where anticipated hydrogen needs are met only by renewably-generated hydrogen could be challenging to implement. While renewable energy growth is accelerating globally, the bulk of the new renewable capacity will be dedicated to decarbonizing the existing grid.
Thankfully, there are a variety of potential technologies and deployment strategies that can maximize the success of a low-emissions hydrogen economy. On the one hand, clean, always-available power, also known as 24/7 power, such as nuclear energy or superhot rock geothermal energy could help by increasing the capacity factor for electrolytic hydrogen production. There is also more than one way to produce low-emissions hydrogen; “blue” hydrogen can help scale production alongside “green” hydrogen. However, this option is not without its own challenges that must be addressed, namely scaling the carbon capture infrastructure needed to capture, deliver, and sequester the carbon and ensuring that there is rigorous fugitive emissions tracking and abatement for the upstream natural gas supply.
All means of low-emissions hydrogen production have their own obstacles, and developing as many of these options as possible will ensure the world has access to a suite of complementary climate tools that can be deployed and adapted to a variety of geographies, business models, resource constraints, and climate conditions.
1 Please note that consumption varies depending upon whether electricity is used instead of natural gas for common end uses like heating, cooking, and clothes drying. Using EIA data, CATF calculations show natural gas consumption per U.S. residential customer was 5,392 standard cubic feet per month in 2021. This is around 5.63 million British thermal units (MMBTU) or 1649 kilowatt-hours (kWh) per month.
2 The readily available water at a facility may require additional processing to meet the stringent quality requirements for steam methane reforming or electrolysis. As a result, actual raw water consumption may vary depending upon available quality. The calculations listed above assume that the water is already treated to the required quality and does not include cooling water considerations for auxiliary equipment. According to the EPA, the average U.S household water consumption was 300 gallons (1136 liters) per day in 2016. For additional information on how actual raw water consumption may vary depending upon available quality, see GHD’s webpage.
3 Please note that the number quoted above is for the electricity consumed, not the amount of generation capacity required to power the electrolysis plant. The generation capacity required will depend upon how often the electricity is available during the day, otherwise known as the capacity factor. The capacity factor varies for different renewable energy technologies, typically being 10-20% for solar PV and 30-50% for offshore wind. This factor can be changed in the tool to demonstrate the value of having clean, firm power that’s available 24/7. EIA data shows the average household electricity consumption was 10,632 kWh/year.