Hydrogen Carbon Footprinting

Globally Hydrogen as a fuel is getting lot’s of traction. Today equipment required to produce, store, and utilize hydrogen is commercially ready and global efforts to produce it at scale are ramping up.

Regulatory frameworks such as the Paris Agreement and more recently the European Green Deal, Inflation Reduction Act (IRA), India’s Green Hydrogen Mission and formation of the European Hydrogen Bank are quickly making the hydrogen industry a reality. The IRA is a strong economic enabler providing subsidies of up to $3 per kg H2. Despite significant efforts, the hydrogen industry is yet to address numerous technical, economic and policy challenges. One of these challenges revolves around hydrogen’s carbon foot-printing and color nomenclature.

Carbon footprint of energy technologies

While fossil fuel carbon footprint is known, we tend to ignore the carbon footprint of renewables over a lifetime. The majority of these emissions come from manufacturing processes, which today rely heavily on fossil fuel based #electricity or various forms of carbon for processing respective components.

For example, the #steel used in the majority of these technologies is responsible for roughly 7-9% of global carbon dioxide emissions. Also, #polysilicon production relies on coal to reduce silica and produce metallurgical grade silicon with the intention to convert it further into #solar panels or other semiconductor uses.

Some other major sources of carbon dioxide emissions in renewable power generation come from #transportation of these technologies from place of #manufacture to place of deployment. In addition, some #renewableenergy technologies may require solid foundations for deployment or additional concrete structures, as in #hydropower where reservoir-based hydropower schemes require concrete dams, spillways, and power houses.

The life cycle of greenhouse gas emissions from electricity generation from renewable energy sources and nuclear have significantly lower carbon dioxide footprint than fossil fuel-based generation, some renewable energy technologies can reach levels higher than 200 g of CO2e per kWh (Figure 1).

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Figure 1. Greenhouse gas emissions of various energy generation technologies presented as an average over their lifetime. Values are presented in grams of CO2 per kWh of energy generated. Presented data comes from NREL’s report: Nicholson, Scott and Heath, Garvin (2021) Life Cycle Emissions Factors for Electricity Generation Technologies. National Renewable Energy Laboratory.

Carbon footprint of hydrogen production per energy source:

Using these NREL numbers and assuming electrolyzer power consumption in the range of 48-58 kWh/kg H2, the carbon footprint per kg of generated hydrogen has been derived. The calculations do not include emissions from hydrogen transportation, compression, or further conversion into hydrogen derivatives. Emissions from manufacturing of electrolyzer and other relevant equipment and emissions from deployment of electrolyzer facilities have been omitted as well. As such, these numbers might be higher.

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Figure 2. Indicative carbon footprint range for hydrogen production from different energy sources. Presented numbers are based on NREL values presented in Figure 1, and assumption of electrolyzer power consumption of 48-58 kWh per kg of H2. The above values do not include emissions from hydrogen transportation, compression, or further conversion into hydrogen derivatives. Carbon footprint values for steam methane reforming and coal gasification are taken from Rocky Mountain Institute: Koch Blank, Thomas and Molly, Patrick (2020) Hydrogen’s Decarbonization Impact for Industry – Near-term Challenges and Long-term Potential. Rocky Mountain Institute.

While hydrogen production using renewable energy or nuclear has a significantly lower carbon footprint compared to hydrogen using electricity from fossil fuels, in some cases, it is difficult to call renewable hydrogen carbon-free (Figure 2). #biomass presents an interesting case, where carbon dioxide emissions vary from negative 48 up to nearly 76 kg of CO2e per kg H2. This makes produced biomass-based hydrogen either carbon negative or comparable to that of fossil fuels in terms of carbon intensity.

Certification schemes and Way Forward

There is ongoing debate around low-carbon hydrogen certification. Based on carbon footprint, hydrogen is given different color classification. Carbon intensities (1 to 5 Kg CO2e per kg H2) differ in various certification schemes across the globe. Some countries may have their own certification schemes, while for others it is still work in progress.

As we develop hydrogen projects, we need to be mindful that it is not enough to assume that hydrogen produced from renewable energy via water electrolysis will always have to be classified green or low-carbon, and that it is necessary to understand hydrogen’s carbon footprint at each step of the #valuechain.

#scope1#scope2 and #scope3 accounting and reporting by various stakeholders could play an important role to certify the color of Hydrogen.

It is possible, as more renewables come online, the carbon footprint of renewable energy generation will decrease as more renewable energy will be used to extract and process raw materials for these technologies. The same applies to transportation of equipment and deployment of renewable generation.

There is a need to develop standard global color certification scheme to avoid cross border trade disputes which may arise based on carbon intensity in hydrogen and its byproducts. As hydrogen industry matures, global standardization of certification schemes needs to be done to meet #producer#customer, and #regulators needs.

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Author: Manoj Kumar Singh (Founder- Net Zero Think Private Limited)