Abstract
Hydrogen and ammonia have been promoted as energy carriers for exporting energy from renewables-rich countries. This article presents a life cycle assessment on the export of hydrogen and ammonia from New Zealand to Japan. It encompasses production of hydrogen by electrolysis in New Zealand, conversion to ammonia (where applicable), liquefaction, transport to Japan and combustion in a thermal power station.
The life cycle greenhouse gas emissions of energy carriers under present conditions are 0.61 kg CO2eq per kWhe output. This is higher than the carbon intensity of Japan's current electricity generation, so energy carriers provide no climate benefit for electricity generation. The emissions are largely from the supply of electricity for production: for every 1 kWhe output at the power station where the energy carrier is burnt, 5.1 kWhe input is needed for energy carrier production due to energy losses. The findings underscore the importance of decarbonizing the electricity grid in the exporting country if genuine carbon savings are to be realised.
•Carbon emissions quantified for New Zealand to Japan energy carrier trade.•New Zealand electricity supply is the main contributor to emissions.•Carbon savings are achieved if New Zealand electricity is decarbonised.