Storing energy as hydrogen is seen by many as a critical part of the energy transition and the road to net-zero emissions. That goes for hard-to-electrify transport applications as well as a wide range of industrial and domestic heating, cooking and other applications.
A new study and Well-to-Tank (WTT) model by Element Energy, commissioned by Zemo Partnership, identifies a range of pathways for the production, distribution and dispensing of low carbon hydrogen to transport end-users. It shows the energy requirements and greenhouse gas emissions resulting from each potential pathway, as well as the infrastructure requirements related to each choice.
The research looks at a combination of six production configurations, three distribution pathways, and two dispensing options – a total of 32 potential pathway combinations.
The work identifies the greenhouse gas emissions associated with each hydrogen supply chain pathway, based on technologies available today, as well as those expected to be commercialised in the medium-term such as offshore electrolysis, gas reformation with carbon capture and storage (CCS) and waste gasification with CCS.
It shows that fundamental choices exist in terms of the production of ‘green’ hydrogen using electrolysis powered by renewable electricity or ‘blue’ hydrogen, primarily produced by reforming fossil natural gas combined with CCS. It also looked at the implications of using biomethane in place of fossil gas and hydrogen derived entirely from biogenic waste.
The study also considers the energy use together with emissions arising along the full production, distribution and dispensing pathway, including unavoidable – or fugitive – emissions likely to arise during the process. It shows that there is a wide variation in the emissions associated with each of the alternative pathways, depending on the carbon footprint of the energy and feedstocks used.
Carbon negative possible
The work suggests that renewables-based electrolysis is expected to represent one of the lowest emissions pathways in the medium-term. Natural gas reformation using emerging autothermal (ATR) technology with CCS could also significantly reduce emissions compared to current industrial steam methane reforming (SMR) process for so called ‘grey’ hydrogen. There are even potential pathways to generate carbon-negative hydrogen when biomethane is used, or through the gasification of waste, allied with CCS.
Whilst the study showed GHG emissions can be almost eliminated, improvements in the efficiency of the process of electrolysis are expected to contribute to a modest reduction in the energy intensity of this pathway in the medium-term. There are opportunities to co-locate hydrogen production with renewable energy, using surplus or currently curtailed energy at times of high production/low demand.
The study provides a detailed model allowing new pathways to be assessed and gives an overview of the quality of the data used in the analysis, identifying areas where further work and monitoring is needed.