• Energy Research

Abstract The war in Ukraine caused Europe to more than double its imports of liquefied natural gas (LNG) in only one year. In addition, imported LNG remains a crucial source of energy for resource-poor countries, such as Japan, where LNG imports satisfy about a quarter of the country’s primary energy demand. However, an increasing number of countries are formulating stringent decarbonization plans. Liquefied hydrogen and liquefied ammonia coupled with carbon capture and storage (LH2-CCS, LNH3-CCS) are emerging as the front runners in the search for low-carbon alternatives to LNG. Yet, little is currently known about the full environmental profile of LH2-CCS and LNH3-CCS because several characteristics of the two alternatives have only been analyzed in isolation in previous work. Here we show that the potential of these fuels to reduce greenhouse gas (GHG) emissions throughout the supply chain is highly uncertain. Our best estimate is that LH2-CCS and LNH3-CCS can reduce GHG emissions by 25%–61% relative to LNG assuming a 100 year global warming potential. However, directly coupling LNG with CCS would lead to substantial GHG reductions on the order of 74%. Further, under certain conditions, emissions from LH2-CCS and LNH3-CCS could exceed those of LNG, by up to 44%. These results question the suitability of LH2-CCS and LNH3-CCS for stringent decarbonization purposes.

replying to M. N. Hayek et al. Nature Climate Change https://doi.org/10.1038/s41558-020-0766-4 (2020)

Abstract Buildings are an important contributor to China's energy consumption and attendant CO2 emissions. Measures to address energy consumption and associated emissions from the buildings sector will be an important part of strategy to reduce the country's CO2 emissions. This study presents a detailed, service-based model of China's building energy demand, nested in the GCAM (Global Change Assessment Model) integrated assessment framework. Using the model, we explored long-term pathways of China's building energy demand and identified opportunities to reduce greenhouse gas emissions. A range of different scenarios was also developed to gain insights into how China's building sector might evolve and what the implications might be for improved building energy technology and carbon policies. The analysis suggests that China's building energy growth will not wane anytime soon, although technology improvement will put downward pressure on this growth: In the reference scenarios, the sector's final energy demand will increase by 110–150% by 2050 and 160–220% by 2095 from its 2005 level. Also, regardless of the scenarios represented, the growth will involve the continued, rapid electrification of the buildings sector throughout the century, and this transition will be accelerated by the implementation of carbon policy.

Abstract This study incorporates the energy demands of water abstraction, treatment, distribution, and post-use wastewater treatment into the Global Change Analysis Model, an integrated human-Earth systems model, and analyzes a range of scenarios that estimate the future evolution of this demand of energy. The study complements research on historical and future water-for-energy, and builds on bottom-up estimates of historical energy-for-water (EFW), by integrating EFW into nation-level energy statistics, where EFW is normally categorized with other energy use in the commercial and public services, industrial, agricultural, and/or electric power sectors. This development allows more resolved projections of future energy demands in general, and in this study, allows for assessment of the energy implications of improvements in water access and water quality that are consistent with the sustainable development goals (SDGs). In our baseline scenario, EFW increases by 2.6 times from 2015 to 2050, and in the SDG scenario with enhanced water access, standards for treatment of wastewater, and irrigation, the consequent EFW demands quadruple from 2015 to 2050. The study highlights the value of integrated, multi-sector analysis in quantifying the future impacts of the SDGs and other aspirational targets.

The Paris Agreement requires countries to articulate near-term emissions reduction strategies through to 2025 or 2030 by communicating nationally determined contributions (NDCs), as well as encouraging the formulation of long-term low-emission development strategies (Article 4.19) 1 . In response, many countries have either submitted or are preparing mid-century strategies 2 . Most NDCs set high-level near-term goals—such as limits on emissions or emissions intensity 3 —which do not provide information about the extent to which they lay the foundations of technology, infrastructure and institutions for deeper reductions in the future, which is a key question for decision makers. Here, using a state-level model of the US embedded within a global integrated assessment model 4,5 , we demonstrate that although the US NDC lies on a straight-line emissions pathway towards its mid-century strategy, the resulting energy system transitions involve nonlinear transformations. The rates of capacity additions and capital investments in electricity generation beyond 2025 are more than three times the rates during the next decade. Our results demonstrate the need for global stocktaking exercises to evaluate the NDCs using metrics broader than emissions to better illuminate their effectiveness in addressing the Paris Agreement’s long-term goals 6,7 . Achieving the longer-term goals of the Paris Agreement and transformation to a low-carbon society requires an acceleration in electricity generation investment and capacity addition above that outlined in the US Nationally Determined Contribution.

AbstractThe transport sector is a crucial bottleneck in the decarbonization challenge. To study the sector’s decarbonization potential in the wider systems perspective, we couple a large-scale integrated assessment model, Regionalized Model of INvestments and Development (REMIND), to a detailed transport model, Energy Demand Generator-Transport (EDGE-T). This approach allows the analysis of mobility futures in the context of long-term and global energy sector transformations, at a high level of modal and technological granularity and internal consistency. The runtime of the coupled system increases by ~ 15–20% compared with a REMIND standalone application, and first convergence tests are promising. To illustrate the capabilities of our modeling approach, we focus on a reference pathway for Europe. Preliminary results indicate that transport service demands grow in the next decades for both passenger and freight transport. Transport system emissions are expected to decrease in the same time range, due to a shift towards electric drivetrains, advanced vehicles, more efficient modes as well as a slight increase in the share of biofuels.

This paper discusses a new U.S. building module in the MiniCAM integrated assessment model, and it presents a scenario based on that module.