Hydrogen Production
- [Hydrogen Production - US Department of Energy]
- Overview
Hydrogen can be produced from diverse, domestic resources including fossil fuels, biomass, and water electrolysis with electricity. The environmental impact and energy efficiency of hydrogen depends on how it is produced. Several projects are underway to decrease costs associated with hydrogen production.
Currently, most hydrogen is produced from fossil fuels, specifically natural gas. Electricity -- from the grid or from renewable sources such as wind, solar, geothermal, or biomass -- is also currently used to produce hydrogen. In the longer term, solar energy and biomass can be used more directly to generate hydrogen.
Today, about 95% of the hydrogen produced in the United States comes from natural gas. It’s created using steam methane reforming, which basically uses high temperatures to convert steam and methane into hydrogen gas and carbon dioxide.
- Hydrogen Gas
Hydrogen is the most basic of all Earth elements. The hydrogen atom is made up of a single proton and a single electron. As such, it is very abundant, but it doesn’t really exist as a separate form of matter. Instead, it is usually combined with other elements. To separate hydrogen gas from its companion substances takes a lot of effort, but it produces a powerful, nearly clean source of energy. As a gas, it can be used in fuel cells to power engines.
Hydrogen gas is extracted from water by a technique known as electrolysis, which involves running a high electric current through water to separate hydrogen and oxygen atoms. The electrolysis process is pretty expensive since it involves high energy expenditure.
The energy used to generate electricity in the electrolysis process is harnessed from fossil fuels like oil, natural gas or coal. It can also be tapped from renewable energy sources like solar, wind and hydropower to ensure there are no greenhouse gas emissions. Obtaining volumes of hydrogen by this method is still under research to establish a viable method of generating it domestically at a relatively low cost.
Another method of hydrogen gas extraction is steam-methane reforming or steam extraction, which entails the separation of hydrogen atoms in methane from carbon atoms. It is the current technique used to obtain hydrogen gas in vast quantities. The downside to steam-methane reforming is that it emits a lot of greenhouse gases like carbon dioxide and carbon monoxide to the atmosphere, which are recipes for global warming.
To obtain electricity from the hydrogen gas, it is conveyed to fuel cells where it combines with oxygen, and the result is a chemical reaction that generates electricity and heat. The hydrogen gas can also just be burned to power vehicle engines. The byproducts of this chemical reaction are water and carbon that is used to produce methane and coal.
- Key Hydrogen Production Pathways
Hydrogen can be produced from diverse, domestic resources including fossil fuels, biomass, and water electrolysis with electricity. The environmental impact and energy efficiency of hydrogen depends on how it is produced. Several projects are underway to decrease costs associated with hydrogen production.
Currently, most hydrogen is produced from fossil fuels, specifically natural gas. Electricity -- from the grid or from renewable sources such as wind, solar, geothermal, or biomass -- is also currently used to produce hydrogen. In the longer term, solar energy and biomass can be used more directly to generate hydrogen.
Today, about 95% of the hydrogen produced in the United States comes from natural gas. It’s created using steam methane reforming, which basically uses high temperatures to convert steam and methane into hydrogen gas and carbon dioxide.
The challenge is, global demand for hydrogen and its emerging applications could increase by a factor of ten, surpassing our current infrastructure for producing and delivering hydrogen.
- Natural Gas and Other Fossil Fuels
Fossil fuels can be reformed to release the hydrogen from their hydrocarbon molecules and are the source of most of the hydrogen currently made in the United States. Combining these processes with carbon capture, utilization, and storage will reduce the carbon dioxide emissions.
Natural gas reforming is an advanced and mature hydrogen production process that builds upon the existing natural gas infrastructure.
- Renewable and Grid Electricity
Green hydrogen is hydrogen produced by splitting water using renewable electricity. The process is called electrolysis. The electricity used to power the electrolysis comes from renewable sources like wind, water, or solar.
Green hydrogen is also called renewable hydrogen. It's the cleanest and most sustainable hydrogen because it generates no polluting emissions into the atmosphere.
Green hydrogen is used in transport, providing a sustainable mobility alternative.
Green hydrogen has significantly lower greenhouse gas emissions than grey hydrogen, which is derived from fossil fuels without carbon capture.
The carbon intensity of green hydrogen depends on the carbon neutrality of the source of electricity. The more renewable energy there is in the electricity fuel mix, the "greener" the hydrogen produced.
Green hydrogen is two to three times more expensive to produce than fossil references. Hydrogen pipelines can be 10-50% more expensive.
- Solar: Sunlight can directly or indirectly provide the energy to produce hydrogen. This resource is abundant, but it is diffuse and only available for a portion of the day.
- Biomass: Biomass is an abundant renewable resource that can be produced domestically, and it can be converted to hydrogen and other byproducts through a number of methods. Because growing biomass removes carbon dioxide from the atmosphere, the net carbon emissions of these methods can be low.
- Wind: Wind is an abundant but variable resource for generating electricity. Wind-generated electricity can power water electrolysis to produce hydrogen, which could be used to fuel vehicles, or stored and then used in fuel cells to generate electricity during times of the day when the wind resource is low.
[More to come ...]
