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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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Alkali-activated materials

This paper, which forms part of the UNEP White Papers series on Eco-Efficient Cements, provides a brief discussion of the class of cementing materials known as ‘alkali-activated binders’, which are identified to have potential for utilization as a key component of a sustainable future global construction materials industry. These cements are not expected to offer a like-for-like replacement of Portland cement across its full range of applications, for reasons related to supply chain limitations, practical challenges in some modes of application, and the need for careful control of formulation and curing. However, when produced using locally-available raw materials, with well-formulated mix designs (including in particular consideration of the environmental footprint of the alkaline activator) and production under adequate levels of quality control, alkali-activated binders are potentially an important and cost-effective component of the future toolkit of sustainable construction materials.

36 MATERIALS SCIENCE↗

Carbon dioxide reduction potential in the global cement industry by 2050

This paper, which is a contribution to the UNEP series on Eco-Efficient Cements, examines the role of material-based solutions to reducing CO{sub 2} emissions from cement production considering factors that could influence implementation. Global urbanization has led to an increase in demand for cement and cement-based materials. With its growth in consumption, the associated CO{sub 2} emissions from its production are raising concern. However, the role of mitigation strategies in a global context that account for regional material availability and degree of market adoption have yet to be considered. This work shows that the 2 °C scenario targets for 2050 can be met through increased use of calcined clay and engineered filler with dispersants. The introduction of new Portland clinker-based cement alternatives, use of alkali-activated materials, and improvement of efficiency of cement use could further contribute to reduction goals. There are currently-available technologies for reduction that could be rapidly implemented.

36 MATERIALS SCIENCE↗

Eco-efficient cements: Potential economically viable solutions for a low-CO2 cement-based materials industry

The main conclusions of an analysis of low-CO{sub 2}, eco-efficient cement-based materials, carried out by a multi-stakeholder working group initiated by the United Nations Environment Program Sustainable Building and Climate Initiative (UNEP-SBCI) are presented, based on the white papers published in this special issue. We believe that Portland-based cement approaches will dominate in the near future due to economies of scale, levels of process optimisation, availability of raw materials and market confidence. Two product-based approaches can deliver substantial additional reductions in their global CO{sub 2} emissions, reducing the need for costly investment in carbon capture and storage (CCS) over the next 20–30 years:1.Increased use of low-CO{sub 2} supplements (SCMs) as partial replacements for Portland cement clinker. 2.More efficient use of Portland cement clinker in mortars and concretes. However, other emerging technologies could also play an important role in emissions mitigation in the longer term, and thus merit further investigation.

36 MATERIALS SCIENCE↗

An editorial to the Special Issue on “Severe climate Risks”

The history of this Special Issue (https://www.sciencedirect.com/special-issue/10JD7LNJNQ0) indirectly dates back to the early 1990s, when the signature of the United Nations Framework Convention on Climate Change kicked-off an international political process based on one overarching and foundational principle: to avoid “dangerous anthropogenic interference with the climate system” at the global level. More than three decades later, such a principle remains central, though complementary aims made their way through the climate negotiation process, such as the importance of ensuring equity and justice, to give just one example here. Scientific knowledge also considerably progressed and we know more about the range of risks that climate change imposes and will continue to impose to the biosphere and humankind, worldwide and at all territorial levels. It is also clear that societal responses to these risks —“climate adaptation” as we know it— are increasingly happening, but definitely not at the pace of climate risk trends (Berrang-Ford et al., 2021, Erisken et al., 2021, Olazabal and Ruiz De Gopegui, 2021, Magnan et al., 2023a, Reckien et al., 2023, UNEP, 2023). As a result, concerns have emerged over the recent years in both the scientific and policy arenas around the idea that societies may not be able to address all climate risks, and that limits to adaptation and induced residual risks need to be considered more seriously. Such concerns further highlight the continuing importance of the imperative to minimise dangerous anthropogenic interference with the climate system, at any scale. But what does “dangerous interference” mean? How can we decide that we are entering the “dangerous” space, compared to a broader range of climate risks that would qualify as problematic but not necessarily “dangerous”? Who should make such a decision? Which conditions drive risk severity over time, including in the future? And what would be the environmental, economic, social and cultural implications of prioritising some climate risks over others? The Intergovernmental Panel on Climate Change (IPCC) was a pioneer in addressing such questions through the development of the “Key Risks” framing that describes those climate risks having the potential to become dangerous or “severe” over the course of this century (Schellnhuber et al., 2006, Schneider et al., 2007, Oppenheimer et al., 2014, O’Neill et al., 2022). The Fifth and Sixth assessment cycles (AR5 and AR6) went a step further by identifying about 120 Key Risks across regions and sectors, and clustering them into 8 “Representative Key Risks” covering a range of geographical systems (low-lying coasts, and to terrestrial and ocean ecosystems), sectors (critical infrastructure, living standards, human health, food security, and water security) and human dimensions (peace and mobility) (Oppenheimer et al., 2014, O’Neill et al., 2022). This Special Issue was born of the efforts of a range of authors, during the development of the IPCC AR6 main Assessment Report between 2019 and 2022, to characterise Key Risks and Representative Key Risks, and advance knowledge on what shapes “severe climate risks” conceptually as well as in the real-world. The series of papers forming this Special Issue is not intended to cover the topic exhaustively, but rather to give readers an overview through the following narrative: defining “severe climate risks” is highly challenging (Magnan et al., 2023b), but knowledge is expanding on the driving climate hazards (Tebaldi et al., 2023) and their implications on geographical systems, sectors and human dimensions, using here food security (Mirzabaev et al., 2023), human mobility (Gilmore et al., 2024) and peace (Buhaug et al., 2023) as illustrative examples. The overall intention is to support especially decision-makers, whatever the scale or sector considered, in asking severity-driven questions to identify sector- and context-specific “priority” risks from climate change.

54 ENVIRONMENTAL SCIENCES↗

Cost-Benefit Analysis for Energy Efficient Refrigerators and Freezers in Uganda

Refrigeration appliances and equipment available on the market are manufactured with a wide range of energy performance. The goal of this report is to perform a cost-benefit analysis, providing policy recommendations to develop standards and labels for refrigerators in Uganda: in particular, an analysis of the cost-effectiveness of adopting the UNEP U4E MRG for refrigerators given the local context in Uganda.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Assessment of Seasonal Energy Performance for Room Air Conditioners in Multiple Climates

This report provides a general approach for adopting a seasonal energy efficiency metric by examining the climate-specific temperature bin distribution for air conditioner use, the seasonal energy efficiency results according to International Standards Organization (ISO) 16358 by climate region, and the relationships in seasonal energy efficiency across regional metrics. This approach could make the seasonal efficiency metric values comparable with those from other countries with standards consistent with ISO 16358. Policy action and market transformation can be accelerated and effectively harmonized with other regional or international efforts by adopting a seasonal energy efficiency metric. The framework and methodology described in this report have been applied in the following publications: Shaffie et al. 2022, Park et al. 2021, Park et al. 2019, and UNEP 2019a.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗