When considering which form of energy is going to replace fossil fuels, hydrogen is often the fuel that people think of. The portability of compressed hydrogen fits well with existing fuel infrastructure and hydrogen has been shown to fuel cars, buses, boats, trains and even aircraft.
In addition, hydrogen fuel also plays the somewhat less glamorous, but arguably more important, role of providing backup power to generators. Green hydrogen is a model fuel because it produces zero emissions.
Generating Hydrogen Fuel
There are two different methods of sourcing hydrogen fuel:
- Steam methane reforming (SMR) – a process which takes fossil fuels and generates brown hydrogen
- Water electrolysis – a process where water is split using electricity (electrolysis) to generate green hydrogen and oxygen.
The green hydrogen produced via electrolysis is cleaner than brown hydrogen. The electricity required to drive electrolysis can be sourced from renewable sources, such as solar, wind or hydroelectric, allowing the generation of purely green fuel.
Brown Hydrogen’s Environmental Impact
Using hydrogen to fuel vehicles is important to many consumers who care about their carbon dioxide footprint and to reduce their impact on the climate. However, if it is brown hydrogen produced via SMR then the environmental cost is still high.
SMR generates hydrogen from methane or coal, and the process itself generates carbon dioxide. For every 1 T of hydrogen produced by SMR, 12 T of carbon dioxide is produced, and this can be as high as 18 T in cases where coal syngas is used as the feedstock. For this reason, using brown hydrogen is actually worse for the environment than directly using fossil fuels.
Using Water Electrolysis to Produce Renewable Hydrogen
The need for new forms of renewable energy is the main factor driving investment and research in the hydrogen fueling industry. Water electrolysis, which requires just water and a renewable energy source, can produce fuel without any carbon dioxide emissions.
Vehicles powered using hydrogen fuel cells are carbon neutral and can be fueled at a faster rate than electric vehicles due to the high energy density of hydrogen, which means it provides more energy per unit weight. In addition, hydrogen fuel cells have a greater lifetime than electric batteries and can be produced at a lower cost.
Fuel Vs CO2 Emissions
||Pounds of CO2 produced per mile driven at 66 MPGe
|Green Hydrogen: Water Electrolysis via 100% Renewable Energy
|Brown Hydrogen: SMR
|Charging Electric Battery: via US Grid
|Calculations derived from EIA and EPA data
This information has been sourced, reviewed and adapted from materials provided by Nel Hydrogen.
For more information on this source, please visit Nel Hydrogen.