# Ammonia, methanol and e-fuels: Engineering and performance Why turning fuel back into electricity wastes most of it Source page: https://www.materialinsights.org/energy/e_efuels_store/sg-eng/ What this tab covers Engineering and operating performance: round-trip efficiency, whether power and energy can be scaled separately, footprint and siting, and safety. E-fuels are easy to store and ship but convert electricity back to electricity at poor efficiency; they make most sense where the fuel is used directly as fuel or feedstock. #### Round-trip efficiency Unfavourable The Royal Society estimated overall efficiency from renewable power to useful output of 28-39% for ammonia used in a solid oxide fuel cell, 17-24% in an engine and 15-25% if ammonia is cracked back to hydrogen for a fuel cell, against 26-35% for hydrogen used directly in a fuel cell. Cracking ammonia has a theoretical minimum loss of about 7%. Carbon-based fuels add a CO2 capture step and synthesis losses.^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) Ammonia to solid oxide fuel cell 28-39%^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) Ammonia to engine 17-24%^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) Ammonia cracked to H2 then PEM fuel cell 15-25%^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) #### Power and energy decoupling Favourable Fully decoupled: electrolysers and synthesis plants set charging rate, tanks set energy, and turbines, engines or fuel cells set output. Tanks are cheap per unit of energy: a 10,000 tonne refrigerated ammonia tank costs GBP 20-40 million, or about GBP 2,000-4,000 per tonne stored (calculated).^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) 10,000 t refrigerated ammonia tank GBP 20-40 million^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) Per tonne stored about GBP 2,000-4,000 (calculated)^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) #### Footprint and siting flexibility Favourable Production is best sited where solar and wind are cheap and land is available, as in India, where one 2025 auction contract supplies a fertiliser plant in Madhya Pradesh. The liquid fuels then move through existing ports, tankers and pipelines. E-methane can use existing LNG export plants, as in a Cameron, Louisiana project announced by Japanese gas utilities and Mitsubishi in 2023.^[3](https://www.pv-magazine-india.com/2025/08/05/secis-latest-auction-yields-green-ammonia-price-of-inr-51-8-per-kg/)^[8](https://argusmedia.com/en/news-and-insights/latest-market-news/2520845-viewpoint-co2-counting-key-to-japan-s-e-methane-plan) Planned Cameron e-methane exports to Japan (2023 plan) 130,000 t/yr by 2030^[8](https://argusmedia.com/en/news-and-insights/latest-market-news/2520845-viewpoint-co2-counting-key-to-japan-s-e-methane-plan) #### Safety and thermal runaway risk Mixed No thermal runaway, but toxic and flammable hazards. Under the EU Seveso III directive on major accidents, sites holding 50 t of anhydrous ammonia fall under lower-tier rules and 200 t under upper-tier rules; for methanol the thresholds are 500 t and 5,000 t, and for petroleum products and alternative fuels 2,500 t and 25,000 t. Ammonia combustion must also be controlled to avoid nitrogen oxides and nitrous oxide.^[1](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf)^[10](https://www.legislation.gov.uk/cy/eudr/2012/18/annexes/2012-07-04) Seveso III ammonia thresholds 50 t lower tier; 200 t upper tier^[10](https://www.legislation.gov.uk/cy/eudr/2012/18/annexes/2012-07-04) Seveso III methanol thresholds 500 t; 5,000 t^[10](https://www.legislation.gov.uk/cy/eudr/2012/18/annexes/2012-07-04) #### Sources 1. [Ammonia: zero-carbon fertiliser, fuel and energy store (policy briefing)](https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf) The Royal Society, 2020 2. [SECI's latest auction yields green ammonia price of INR 51.8 per kg](https://www.pv-magazine-india.com/2025/08/05/secis-latest-auction-yields-green-ammonia-price-of-inr-51-8-per-kg/) pv magazine India, 2025 3. [Viewpoint: CO2 counting key to Japan's e-methane plan](https://argusmedia.com/en/news-and-insights/latest-market-news/2520845-viewpoint-co2-counting-key-to-japan-s-e-methane-plan) Argus Media, 2023 4. [Directive 2012/18/EU (Seveso III), Annex I](https://www.legislation.gov.uk/cy/eudr/2012/18/annexes/2012-07-04) legislation.gov.uk (EU directive text as adopted), 2012 ## Other sections - [Summary](https://www.materialinsights.org/energy/e_efuels_store/index.md) - [Overview](https://www.materialinsights.org/energy/e_efuels_store/overview/index.md) - [Correlation](https://www.materialinsights.org/energy/e_efuels_store/correlation/index.md) - [Science and technology](https://www.materialinsights.org/energy/e_efuels_store/sg-sci/index.md) - [Economics](https://www.materialinsights.org/energy/e_efuels_store/sg-econ/index.md) - [Impact and additionality](https://www.materialinsights.org/energy/e_efuels_store/sg-impact/index.md) - [What to track](https://www.materialinsights.org/energy/e_efuels_store/tracking/index.md) - [Relationships](https://www.materialinsights.org/energy/e_efuels_store/links/index.md)