Hydrogen's Dark Side: Exploring Its Pollution Potential

Hydrogen is a highly flammable gas that is prone to leaking. The process of producing hydrogen is heavily polluting and can cause air pollution in neighbouring communities. The most common way to produce hydrogen is to separate it from methane gas using extremely high heat and pressure. This process, called steam-methane reformation (SMR), involves burning fossil fuels, which emit harmful pollutants like particulate matter and nitrogen oxides. These gases create smog and can damage lungs, with children being especially vulnerable due to their smaller airways and developing lungs. Additionally, injecting hydrogen into the gas system can create safety hazards in pipelines and household appliances.

Hydrogen combustion can cause NOx emissions, including nitric oxide and nitrogen dioxide, which are hazardous air pollutants

NOx formation occurs when air (which contains nitrogen and oxygen) is exposed to very high temperatures (above 1,500°C). Any type of high-temperature combustion can produce NOx, but hydrogen burns at higher temperatures than natural gas, so its combustion may result in comparably higher NOx emissions. However, hydrogen has a larger stable combustion temperature range, meaning a higher ratio of air to fuel can be used. This additional air effectively dilutes the hydrogen, which cools off the flame and results in lower-temperature combustion, thereby reducing the amount of NOx emissions produced.

The most common way to produce hydrogen is to separate it from methane gas using extremely high heat and pressure. This process is called steam-methane reformation (SMR), and it is heavily polluting. The heat comes from burning fossil fuels, which emit harmful pollutants like particulate matter and nitrogen oxides — gases that create smog and can damage your lungs.

Injecting hydrogen into our gas system could also create safety hazards in our pipelines and household appliances. Today’s gas lines and pipes were not designed for hydrogen, which can embrittle certain metals used in pipes and sealants and make them more likely to crack.

Hydrogen production through steam-methane reformation is heavily polluting, as it involves burning fossil fuels

Any type of high-temperature combustion can produce NOx, which includes nitric oxide and nitrogen dioxide, both hazardous air pollutants. Hydrogen burns at higher temperatures than natural gas, so combustion of pure hydrogen may result in higher NOx emissions. However, this may be offset by the fact that hydrogen has a larger stable combustion temperature range, meaning a higher ratio of air to fuel can be used. This additional air dilutes the hydrogen, cooling the flame and resulting in lower-temperature combustion, which reduces the amount of NOx emissions produced.

Injecting hydrogen into our gas system could also create safety hazards in our pipelines and household appliances. Today's gas lines and pipes were not designed for hydrogen, which can embrittle certain metals used in pipes and sealants, making them more likely to crack.

The process of producing hydrogen also contributes to air pollution in neighbouring communities and pumps climate pollution into our atmosphere. For example, the oil refining company Philips 66 recently entered an agreement with Linde to build the largest hydrogen production facility in the United States. The project is being constructed in St. James Parish, Louisiana, an area already known as "Cancer Alley" due to the high concentration of petrochemical plants and refineries.

Hydrogen embrittlement can make certain metals in pipes and sealants more likely to crack, creating safety hazards

Hydrogen can cause pollution in several ways. Firstly, the process of producing hydrogen can be heavily polluting. Steam-methane reformation (SMR) is the most common way to produce hydrogen, and it involves burning fossil fuels, which emit harmful pollutants like particulate matter and nitrogen oxides. These gases create smog and can damage lungs, especially in children who are more vulnerable to air pollution due to their smaller airways and developing lungs.

Secondly, hydrogen combustion can produce hazardous air pollutants such as nitric oxide (NO) and nitrogen dioxide (NO2). While hydrogen has a larger stable combustion temperature range, which can help reduce NOx emissions, the fact that it burns at higher temperatures than natural gas means that combustion of pure hydrogen may result in higher NOx emissions.

Additionally, injecting hydrogen into our gas system can create safety hazards in pipelines and household appliances. Hydrogen can cause embrittlement in certain metals used in pipes and sealants, making them more prone to cracking. This could lead to leaks and other safety issues.

Overall, while hydrogen may offer some benefits, it is important to recognise that its production and use can contribute to air pollution and pose safety risks that need to be addressed.

Hydrogen is highly flammable and prone to leaking

Today's gas lines and pipes were not designed for hydrogen, which can embrittle certain metals used in pipes and sealants and make them more likely to crack. Hydrogen can also attach to other kinds of molecules, so pure hydrogen is not naturally occurring on Earth. The most common way to produce hydrogen is to separate it from methane gas using extremely high heat and pressure. This process is called steam-methane reformation (SMR), and it is heavily polluting. The heat comes from burning fossil fuels, which emit harmful pollutants like particulate matter and nitrogen oxides — gases that create smog and can damage your lungs.

Any type of high-temperature combustion (e.g. of diesel, gasoline, natural gas, hydrogen) can produce NOx, which include nitric oxide (NO) and nitrogen dioxide (NO2), both hazardous air pollutants. Because hydrogen burns at higher temperatures than natural gas, combustion of pure hydrogen may result in comparably higher NOx emissions. However, this may be offset by the fact that hydrogen has a larger stable combustion temperature range, meaning a higher ratio of air to fuel can be used. This additional air effectively dilutes the hydrogen, which cools off the flame and results in lower-temperature combustion, thereby reducing the amount of NOx emissions produced.

Hydrogen can be dangerous for children, as they are more vulnerable to air pollution

The production of hydrogen itself also contributes to air pollution. The most common method, steam-methane reformation (SMR), involves burning fossil fuels, which emit harmful pollutants such as particulate matter and nitrogen oxides. These gases create smog and can damage lungs, posing a significant threat to human health.

Additionally, hydrogen is highly flammable and prone to leaking. Its injection into the gas system could create safety hazards in pipelines and household appliances. Today's gas lines and pipes were not designed for hydrogen, which can embrittle certain metals, making them more susceptible to cracking.

While hydrogen has a larger stable combustion temperature range, allowing for a higher ratio of air to fuel and potentially reducing NOx emissions, the combustion of pure hydrogen at extremely high temperatures can still result in higher NOx emissions.

Frequently asked questions