Hydrogen Fuel – Green or Blue?
Hydrogen and the Rainbow – What do they Have in Common?
Rainbows are spectral reflections of light passing through atmospheric hydrogen (and other gases), but hydrogen does not come from rainbows. It is abundant in the atmosphere, but to turn it into an energy source it requires a reaction. The only thing hydrogen has in common with the rainbow is two colours: blue and green… and maybe yellow, but too early to tell. The colour refers to how the hydrogen is produced.
What is blue or green hydrogen?
Hydrogen in its abundant form is usually found in methane (CH4) and water (H2O). To use it as a fuel hydrogen must be separated from the other compounds. There are different ways of extracting hydrogen from its source. The source can be natural gas, coal, biomass, or water. According to the Green Hydrogen Coalition, the carbon footprint of how the hydrogen is produced defines its colour. In other words, the source and the process gives the hydrogen its name sake colour.
The most common hydrogen today is that which is produced from natural gas and is extracted through a chemical reaction. There is some hydrogen produced from gasification of solid fossil fuels such as coal. However, it seems over 90% of the hydrogen produced today is sourced from natural gas. Natural gas is methane. The methane is reacted with steam in a process called reforming or steam methane reforming (SMR). This is a thermochemical conversion where the methane reacts with high temperature steam. This conversion produces hydrogen, carbon monoxide, and a small amount of carbon dioxide. The carbon monoxide is then further reacted with water to produce more hydrogen and some carbon dioxide. This type of process requires a supply of high heat. There are still carbon emissions associated with the process of natural gas derived hydrogen. Because of the heat requirement and use of fossil fuels, this type of hydrogen is called grey hydrogen. When the resulting carbon dioxide is removed, captured, and permanently stored underground (like conventional carbon injection into rock formations) then it is called blue hydrogen. Blue hydrogen is considered a low-carbon alternative, whereas grey hydrogen is not. In between blue and grey there is brown hydrogen, which is more carbon intensive since it uses solid fossil fuels like coal as the feedstock.
When natural gas is used to produce hydrogen for energy, it is not combusted. In combustion, the carbon from the methane is not combined with oxygen to create CO2 that is released into the atmosphere. In hydrogen production, the natural gas reacts in a catalyst with added oxygen from steam; therefore, the emissions associated with natural gas combustion do not apply to hydrogen for energy production. Moreover, it is more efficient to produce electricity from blue hydrogen, than it is to directly combust natural gas into energy. A gas-fired plant may be about 42 percent efficient in converting heat to energy, whereas hydrogen power generation could be as much as 60 percent efficient. This means you will get more kWh per volume of natural gas reacted than per volume of natural gas combusted. As such, using blue hydrogen for energy production is a low-carbon alternative and is considered a decarbonization solution.
Green hydrogen is produced from renewable sources such as solar and wind. In this case, hydrogen from renewable sources is produced through electrolysis which uses an electric current to split water into hydrogen and oxygen. The source of the electricity must be renewable energy to be deemed green hydrogen. Hydrogen produced using electrolysis does not have the emissions associated with reforming – there is no carbon dioxide by-product.
Green hydrogen can also be produced from:
- Biogas using SMR.
- Fermented biomass, where bacteria breaks down organic matter to produce hydrogen.
- Municipal waste gasification.
Different colour hydrogen has a different carbon intensity per kilogram of hydrogen produced:
As new forms of hydrogen production develop, we will see other colours referenced such as turquoise hydrogen which uses pyrolysis which breaks down natural gas into hydrogen and solid carbon. However, the major obstacle remains: cost.
How much does it cost to produce hydrogen, and which is the cheapest option?
Overall, production of hydrogen is expensive, which makes it less competitive with conventional fuels. Reforming from natural gas is the cheapest way of producing hydrogen. It makes use of existing pipeline infrastructure and the steam methane reforming technology has already scaled and is a mature process. Because it makes use of existing infrastructure, fossil fuel producers can make a shift to producing hydrogen.
According to the International Energy Agency (IEA), the main driver for the price of hydrogen is natural gas. They estimate the cost of grey hydrogen around EUR 1.50 per kilo. The price increases for blue hydrogen due to the carbon capture and storage component, which costs between EUR 50 to EUR 70 per tonne of CO2. According to the IEA, as the price of carbon increases and the cost between grey and blue will narrow. This is because grey hydrogen will have a greater cost associated with the carbon, making it more financially attractive to invest in CCS (i.e. going from grey to blue). On the other hand, as blue hydrogen technology develops, the cost of producing it and the emissions associated will also reduce. A spin-off startup of Hall Labs (you know, the ones that turned carbon into a diamond?) is looking at this very question of reducing cost and emissions from blue hydrogen by 30 percent.
Green hydrogen adoption is hindered by the cost and availability of electrolysis capacity. Moreover, the cost of green hydrogen will also depend on the cost of the renewable source and its availability. Most grid electricity is not 100% renewables based and may be energy intensive. Adopting more renewable technologies can potentially overcome this obstacle for green hydrogen production.
So, what is next for hydrogen?
As stated above, production of hydrogen is expensive, but there is mature technology that could allow hydrogen to play an important role in the transition to cleaner energy alongside the adoption of fuel cell technology.
Beyond cars and hydrogen fuel cell vehicles, hydrogen can be used for power generation. We are “At the Dawn of the Hydrogen Economy”. There is an increasing interest and growing demand on hydrogen to facilitate the transition to clean energy. There are still critical technical barriers to the development of the hydrogen economy. Our article on fuel cells highlighted some companies that will enable the use of hydrogen, are providing enabling solutions like backup power solutions, engine components, etc.
H2 International stated “hydrogen, as one of several sources in the future energy mix, could meet up to 24 percent of electric power demand across the European Union in 2050”.
Fuel Cell technology allows power to be generated where it will be consumed. This could make it cost efficient and reliable. It also allows energy to be stored and used as needed. Unlike battery storage, there is no need to recharge – as long as there is a supply of hydrogen, there is power generation. Bloom Energy’s Energy Server Platform is an advanced, distributed power generation system that can use natural gas or biogas for power generation. The platform, running on natural gas, produces nearly 60% less carbon emissions compared to the average of U.S. combustion power generation.
Ceres Power Holdings plc, develops SteelCell, a perforated sheet of steel with special screen-printed ceramic layers that converts fuel directly into electrical power. Its products are applied in commercial, data center, automotive, and residential markets.
ITM Power is enabling electrolysis with their products based around a Proton Exchange Membrane technology and its electrolysers are modular allowing customers to customize their electrolyser output capacity for their specific needs. In 2019, ITM Power agreed to lease a new factory in the UK with an electrolyser capacity of 1,000 MW per year, the largest in the world.
NextEra Energy acquires, manages, and own contracted clean energy projects. As of 01 December 2019, the company owned and operated 756 MW worth of solar parks, and 4575 MW of wind farms in the United States. More recently, the company announced it will be investing in a $65 million pilot plant for Florida Power & Light – its first green hydrogen plant.