Study Shows Residual Emissions from Hydrogen

September 8, 2026

Source: E & M powernews

A study by Ifeu and Germanwatch shows that hydrogen and e-fuels can significantly reduce emissions. However, to achieve climate neutrality, industry must also adopt climate-neutral production methods.

Hydrogen and synthetic fuels (e-fuels) can significantly reduce greenhouse gas emissions compared to fossil fuel-based reference products. This is shown by a study conducted by the Heidelberg Institute for Energy and Environmental Research (Ifeu) and the environmental and development organization Germanwatch. According to the researchers, reductions of up to 90 percent were possible in the value chains examined.

The study was conducted as part of the NEET project commissioned by the Federal Environment Agency (UBA). IFEU and Germanwatch analyzed various production and transportation methods for hydrogen and hydrogen-based hydrocarbons. In doing so, they examined the environmental impacts along the entire value chain and identified areas with particularly high emissions.

Infrastructure Causes Residual Emissions

According to the study, greenhouse gas emissions persist even with optimized value chains. For some of the pathways examined, these emissions amount to approximately 10 to 20 percent of those from fossil-based reference products. The study cites the production of the necessary equipment and infrastructure as a major cause.

These include, among other things, wind turbines, photovoltaic modules, and electrolysers, as well as chemical reactors and transportation vehicles. Their production still relies on fossil fuels and raw materials today. Therefore, according to the researchers, completely avoiding these upstream emissions requires industrial production that is largely defossilized.

“The defossilization of the energy supply and the defossilization of industry must go hand in hand,” concludes Thomas Fröhlich, project leader and head of the Resources Division at Ifeu. Daniel Münter, Program Director for Basic Industries at Germanwatch, therefore calls for a stronger focus on the manufacture of the necessary equipment and components.

Criticism of E-Fuel Requirements

The study also identifies a need for action regarding the regulatory framework. According to the researchers, the European Renewable Energy Directive (RED) effectively treats renewable electricity as climate-neutral. The study, however, also takes into account the environmental impacts and greenhouse gas emissions associated with the generation of wind and solar power.

The authors also take a critical view of the current requirements for greenhouse gas reductions in renewable fuels. The RED currently mandates a reduction of at least 70 percent compared to fossil fuel reference products. According to the researchers, this target is insufficient to achieve climate neutrality in the long term.

Furthermore, regulatory requirements have so far focused largely on greenhouse gas emissions. Other environmental impacts, however, have been given insufficient consideration.

Blue Hydrogen Faces Significant Challenges

The researchers also examined blue hydrogen. In this process, natural gas is reformed, and the resulting carbon dioxide is captured and stored. According to the study, under certain conditions, the environmental impacts can be as low as those of green hydrogen.

However, this would require meeting several stringent requirements simultaneously. These include the near-complete elimination of methane emissions throughout the natural gas supply chain and a CO₂ capture rate of more than 98 percent. In addition, the captured CO₂ must be stored safely and permanently, and all process steps must be powered by renewable electricity.

Biogenic CO₂ sources are limited

The production processes for synthetic hydrocarbons require carbon in addition to hydrogen. The study compares various CO2 sources for this purpose, including CO2 from the atmosphere, industrial exhaust gases, and biogenic sources. According to the researchers, biogenic CO₂ can offer advantages because the carbon was previously removed from the atmosphere.

The study identifies biogenic residues and waste materials as particularly suitable. However, their availability is limited, as some of these materials are already being used for other purposes. Additionally, increased demand could trigger displacement effects. For example, mineral fertilizers might be used more extensively, or wood residues could be replaced by virgin wood.

The researchers see the greatest potential in industrial facilities that generate concentrated biogenic CO₂ streams. These include, for example, ethanol production, the pulp industry, and the thermal treatment of municipal solid waste.

The IFEU project NEET is available online.

Author: Susanne Harmsen