Energy Transition

Role of hydrogen in low-carbon energy transition

Abstract: Dr Sergey Paltsev discussed the role of hydrogen as a low carbon solution in reducing emissions across various sectors of the economy including transportation, industrial uses, and for energy storage. He acknowledged hydrogen’s potential benefits, but also noted substantial challenges, such as the high costs and infrastructural demands associated with its production and use. Dr Paltsev recognised the unique context of New Zealand, noting that with our light vehicle fleet, hydrogen may not be the ideal solution for transportation decarbonisation, suggesting instead that New Zealand’s air and maritime traffic sectors might benefit from alternative strategies. Considering factors like New Zealand’s energy security and high electricity costs, Dr Paltsev highlighted the need for significant financial backing and thoughtful consideration before focusing on hydrogen in the energy transition.

Climate and Air Quality Impact of Using Ammonia as an Alternative Shipping Fuel

Abstract: As carbon-free fuel, ammonia has been proposed as an alternative fuel to facilitate maritime decarbonization. Deployment of ammonia-powered ships is proposed as soon as 2024. However, NOx, NH3 and N2O from ammonia combustion could impact air quality and climate. In this study, we assess whether and under what conditions switching to ammonia fuel might affect climate and air quality. We use a bottom–up approach combining ammonia engine experiment results and ship track data to estimate global tailpipe NOx, NH3 and N2O emissions from ammonia-powered ships with two possible engine technologies (NH3–H2 (high NOx, low NH3 emissions) vs pure NH3 (low NOx, very high NH3 emissions) combustion) under three emission regulation scenarios (with corresponding assumptions in emission control technologies), and simulate their air quality impacts using GEOS–Chem High Performance global chemical transport model.

We find that the tailpipe N2O emissions from ammonia-powered ships have climate impacts equivalent to 5.8% of current shipping CO2 emissions. Globally, switching to NH3–H2 engines avoids 16,900 mortalities from PM2.5 and 16,200 mortalities from O3 annually, while the unburnt NH3 emissions (82.0 Tg NH3 yr-1) from pure NH3 engines could lead to 668,100 additional mortalities from PM2.5 annually under current legislation. Requiring NH3 scrubbing within current Emission Control Areas leads to smaller improvements in PM2.5-related mortalities (22,100 avoided mortalities for NH3–H2 and 623,900 additional mortalities for pure NH3 annually), while extending both Tier III NOx standard and NH3 scrubbing requirements globally leads to larger improvement in PM2.5-related mortalities associated with a switch to ammonia-powered ships (66,500 avoided mortalities for NH3–H2 and 1,200 additional mortalities for pure NH3 annually).

Our findings suggest that while switching to ammonia fuel would reduce tailpipe greenhouse gas emissions from shipping, stringent ammonia emission control is required to mitigate the potential adverse effects on air quality.

Mutual Reinforcement of Land-based Carbon Dioxide Removal and International Emissions Trading in Deep Decarbonization Scenarios

Abstract: Carbon dioxide removal (CDR) technologies and international emissions trading are both widely represented in climate change mitigation scenarios, but the interplay among them has not been closely examined.

By systematically varying key policy and technology assumptions in a global energy-economic model, we find that CDR and international emissions trading are mutually reinforcing in deep decarbonization scenarios.

This occurs because CDR potential is not evenly distributed geographically, allowing trade to unlock this potential, and because trading in a net-zero emissions world requires negative emissions, allowing CDR to enable trade. Since carbon prices change in the opposite direction as the quantity of permits traded and CDR deployed, we find that the total amount spent on emissions trading and the revenue received by CDR producers do not vary strongly with constraints on emissions trading or CDR. However, spending is more efficient and GDP is higher when both CDR and trading are available.

Summary: This project aims to build an integrated modeling framework that links highly resolved sectoral models for agriculture and water with the MIT Integrated Global System Model (IGSM), which represents global economic and climate systems. This novel global framework will capture (a) global, inter-regional and inter-sectoral dynamics, (b) highly-resolved local and sectoral dynamics of water and agricultural systems, and (c) multiple channels of climate impacts on the economy.

Food security in Africa under a changing climate – Navigating the energy and agricultural transition to net zero
Drivers and implications of alternative routes to fuels decarbonization in net-zero energy systems

Abstract: Energy transition scenarios are characterized by increasing electrification and improving efficiency of energy end uses, rapid decarbonization of the electric power sector, and deployment of carbon dioxide removal (CDR) technologies to offset remaining emissions. Although hydrocarbon fuels typically decline in such scenarios, significant volumes remain in many scenarios even at the time of net-zero emissions. While scenarios rely on different approaches for decarbonizing remaining fuels, the underlying drivers for these differences are unclear.

Here we develop several illustrative net-zero systems in a simple structural energy model and show that, for a given set of final energy demands, assumptions about the use of biomass and CO2 sequestration drive key differences in how emissions from remaining fuels are mitigated.

Limiting one resource may increase reliance on another, implying that decisions about using or restricting resources in pursuit of net-zero objectives could have significant tradeoffs that will need to be evaluated and managed.

Pages

Subscribe to Energy Transition