Net Zero Carbon Emissions Research Articles

Unlocking underground hydrogen storage potential: Geochemical characterization of North Dakota's geological formation

Underground hydrogen storage offers a promising solution for sustainable energy, with geologic formations such as salt caverns, aquifers, and depleted hydrocarbon reservoirs identified as suitable options for safely storing hydrogen. Some studies have been carried out to investigate hydrogen-rock-fluid interactions. However, none have simultaneously combined experimental analysis and geochemical modeling of the equilibrium and kinetic reactions using a well-characterized North Dakota carbonate formation as a case study to investigate its geochemical characterization and implications. This research explores the mineralogical and fluid composition of specific depleted hydrocarbon reservoirs in North Dakota while investigating the intricate geochemical interplays between hydrogen gas, fluid, and rock formations. This study focused on the Red River Formation, a primary hydrocarbon-producing entity in North Dakota, to unveil its potential for underground hydrogen storage (UHS). This formation's stratigraphic complexity and extensive hydrocarbon yield underscores its significance. We conducted experiments combining analytical tests and geochemical modeling using core samples from the Red River Formation. X-ray diffraction (XRD), X-ray fluorescence (XRF) spectroscopy, and scanning electron microscopy (SEM) techniques were employed to decipher mineralogical and elemental constituents. This study covers areas such as the Bicentennial, Coyote Creek, Horse Creek, and Medicine Poll Hills Fields and identified common minerals such as calcite, dolomite, anhydrite, and quartz, along with essential elements such as oxygen, magnesium, aluminum, and silicon. Geochemical simulations were also performed to evaluate the equilibrium and kinetic reactions expected during hydrogen gas injection into this formation. Our findings revealed stable mineral phases, the absence of detrimental environmental impacts, promising prospects for hydrogen storage in the studied carbonate reservoirs without geochemical alterations and promising a sustainable pathway toward net-zero carbon emissions.

Use of Sustainable Energy Systems in Educational Institutions

Educational institutions like other public and private organizations should try to eliminate their carbon footprint for the achievement of the ambitious 2050 target of net-zero carbon emissions. Several mature, reliable and cost-effective sustainable energy technologies can be used in these institutions replacing the use of fossil fuels and reducing their carbon emissions. Solar energy, wind energy and biomass can be used for heat and electricity generation replacing the use of oil, gas and grid electricity. Additionally, various low-carbon emission technologies including heat pumps, co-generation systems, fuel cells, district heating systems and power storage technologies can be also used in them. The combined use of these technologies in schools, colleges and universities can replace the current use of conventional energy sources reducing or completely eliminating their carbon emissions. The abovementioned benign energy technologies are already used commercially in several sectors proving their reliability and cost-effectiveness. It has been indicated that a plethora of green energy technologies can be used in educational institutions eliminating their carbon footprint achieving the desired global 2050 target of net-zero carbon emissions. Our results could be useful to policy makers and to the authorities of schools, colleges and universities who are willing to promote their environmental sustainability, achieving economic benefits and offering valuable educational opportunities to students.

Observed carbon decoupling of subnational production insufficient for net-zero goal by 2050

Historically, economic growth has been closely coupled to carbon emissions responsible for climate change, but to stabilize global mean temperature, net-zero carbon emissions are necessary. Some economies have begun to reduce emissions while continuing to grow, but this decoupling is not fast enough to achieve global climate targets. Subnational climate actions seem to be crucial for the achievement of these targets. Here, we uncover the effectiveness of subnational efforts by estimating decoupling rates and CO2 emission intensities over the last three decades for over 1,500 subnational regions, encompassing 85% of global emissions, using global data on reported economic output and gridded production-based emissions. Thirty percent of regions with available data have fully decoupled, with higher-income and historically carbon-intensive regions exhibiting higher rates of decoupling and declining emission intensity. Countries of the Organization for Economic Co-operation and Development with greater spending on subnational climate actions show higher decoupling rates, as do subnational regions in EU countries where climate policies have been implemented, highlighting the effectiveness of subnational policies. Moreover, subnational analysis reveals greater variance of decoupling rates within national boundaries than between them and that countries with weaker governance typically show higher variance of decoupling within their borders. If recent rates of production-based carbon decoupling continue, less than half of subnational regions would reach net-zero before 2050, even when accounting for observed acceleration via socioeconomic development and assuming no interregional carbon leakage.

Distrust and reflexive impotence in the net zero transition: findings from a longitudinal deliberative mini-public

Responding to climate change requires that people engage in different forms of climate citizenship. These span from individual consumption choices, to taking part in forms of collective action to steer the behaviour of governments and in the private sector. Here we analyse data from the Net Zero Diaries project to explore how attitudes to different forms of climate citizenship develop as people become more aware about the scale of societal change required to reach net zero carbon emissions by 2050. The Net Zero Diaries project was a deliberative mini-public, composed of 41 citizens broadly representative of the UK adult population, which convened over five months between 2021 and 2022 to debate the UK policies for reaching net zero emissions by 2050. We show that people identify government as the prime actor needed to drive the transition, but doubt that they will act due to a range of constraints vis-à-vis the public and private sector. This tension provides a novel explanation for why some people prioritise forms of individual and consumption focused climate citizenship, whilst also doubting the efficacy of such actions. We conclude by suggesting that efforts to drive more engaged forms of climate citizenship need to attend to underlying feelings about state efficacy, rather than focus on just how the issue of climate change is framed.

On the chemistry of the global warming potential of hydrogen

Hydrogen (H2) is considered a promising fuel to contribute to net-zero carbon emission goals. While hydrogen itself is not a greenhouse gas, leakage of hydrogen fuels causes indirect warming due to hydrogen’s influence on methane, tropospheric ozone, and stratospheric water vapor, with the methane term dominating the impact. Some studies consider a simple four-equation box model to explore the climate consequences of leakage from hydrogen fuel use relative to methane, while others have employed much more detailed global photochemical models. Here we use a comprehensive photochemical box model including 66 reactions to show and quantify how the analogous four-equation system is missing a critical OH feedback, leading it to overestimate the time-integrated methane response to a pulse of hydrogen by over 100%. We estimate a hydrogen global warming potential (GWP) relative to carbon dioxide of 28−11+18 on the 20-year time horizon and 10−4+7 on the 100-year time horizon based on the 66-reaction model and information from the literature. GWPs provide a measure of the relative global warming impact of emission of one gas compared to a selected reference gas per unit mass emitted. While CO2 is generally chosen for the reference, any gas can be used. We present the GWP of H2 using CH4 as the reference, as this choice cancels out some uncertainties that are common to both H2 and CH4. The GWP for H2 relative to CH4 from fossil fuel sources is 0.35−0.06+0.13 on time horizons beyond 15 years; put differently, we find that relative to an equivalent mass of emission of fossil CH4, hydrogen emission has a climate impact about three times smaller. These global warming potentials underscore that hydrogen leakage does contribute to climate change, emphasizing the importance of limiting both hydrogen and methane leakage if global net-zero greenhouse gas emissions are to be achieved by 2050.

Evaluation of the Properties and Compositions of Blended Bio-jet Fuels Derived from Fast Pyrolysis Bio-oil made from Wood According to Aging Test

AbstractThe aviation industry has set ambitious goals for reducing carbon emissions, with the International Civil Aviation Organization targeting net-zero carbon emissions by 2050. Bio-jet fuel is expected to play a crucial role in achieving this target, and the demand for bio-jet fuel is projected to rapidly increase. Bio-oil from fast pyrolysis of lignin, such as waste wood, is considered a promising alternative for production of bio-jet fuel through processes such as hydrodeoxygenation. In this study, the physical properties and compositions of bio-jet fuel produced from wood-derived pyrolysis bio-oil blended with petroleum-based jet fuel as well as their changes during 16 weeks storage were investigated. Consistently, 0%, 10%, 50%, and 100% blended bio-jet fuels were prepared. After 16 weeks of aging, the total acid number of the all-blended bio-jet fuel showed a sharp increase from 12 weeks, reaching over 0.1 mg KOH/g. Additionally, kinematic viscosity showed a steady increase over 16 weeks whereas oxidative stability decreased by approximately 20% at 16 weeks for the 100% bio-jet fuel alone. The final boiling point increased by up to 20% in higher blends of bio-jet fuel and the average molecular weight increased. Bio-jet fuel has a high olefin content, which can further increase during storage, leading to a decrease in the combustion characteristics. This study suggests that using up to 10% the bio-jet fuel in aircraft is safe considering storage stability, but further research is required to confirm this finding.

Pathways to Net-Zero—Innovations and Challenges in Achieving Carbon Neutrality

The global pursuit of net-zero carbon emissions has become one of the most critical challenges of the 21st century, as extreme climate events, rising temperatures, and environmental degradation force a reckoning with the carbon-intensive practices that define many of our industrial, agricultural, and energy systems [...]

Mineralization reaction between CO2 and coal ash produced from underground coal gasification: Implication for in situ carbon sequestration

Underground coal gasification (UCG) represents a promising clean and low-carbon energy technology, which could create a suitable cavity for in situ carbon sequestration by mineralization reaction between CO2 and coal ash produced from UCG. This may assist in achieving a net-zero carbon emission goal for UCG projects. To determine the carbonation efficiency and mineralization potential of CO2 mineral sequestration in abandoned UCG cavity, coal ash produced from the gasification of three different low-rank coal samples was used in this study. A comparative experiment was conducted using a group of high-calcium fly ash from a coal-fired power plant. All mineralization reaction experiments were performed in a high-temperature and high-pressure reactor, with CO2 pressures ranging from 2 to 8 MPa and temperatures ranging from 40 to 80°C. These conditions were selected to simulate the sequestration conditions in the UCG cavity. Real-time monitoring of CO2 pressure in the reactor was used to assess the impact of solid-to-water ratio, temperature, and pressure on the CO2 mineralization. X-ray diffraction and scanning electron microscopy were employed to identify the presence of newly formed carbonate minerals associated with mineralization reaction. The results indicated that the coal ash produced by gasification pretreatment at 900°C contains a substantial quantity of alkaline-earth oxides, such as calcium oxide (CaO), with a relative mass fraction reaching 25.9%. It provided an adequate supply of alkali metal ions for the mineralization reaction, which exhibited comparable efficacy in mineralizing CO2 to that observed in high-calcium fly ash. Without stirring, at lower solid-to-water ratio, the maximum amount of CO2 consumed through mineralization was increased by up to 74.12%. Carbonation efficiency decreased with rising temperatures below 70°C due to the limited dissolution of CO2 in water, it increased with elevated pressure but decreased in the supercritical state, potentially attributable to the dissolution of carbonate minerals in a supercritical CO2 environment. The process of mineralization reaction between CO2 and coal ash aligned well with the Surface Coverage Model (R2 values ranging from 0.92 to 0.99). A preliminary estimation based on Chinese coal reserves revealed that the potential of CO2 sequestration capacity in UCG cavities by mineralization ranging from 29 to 102 Gt, an additional 517 Gt CO2 may be stored when filled with fly ash. This paper provides theoretical bases for predicting the maximum carbonation efficiency under high-pressure and high-temperature conditions in UCG cavities, and research directions for achieving a net-zero carbon emission goal for UCG projects.

A Review of the Sustainability of Helium: An Assessment of Its Past, Present and a Zero-Carbon Future

Helium, as a by-product of the natural gas industry, will be impacted by the decline in consumption of fossil fuels as the world moves towards net-zero carbon emissions. In September 2022, all assets relating to the US government’s previous helium industry were sold. In the US, helium is now only available from private suppliers. In June 2022, Russia banned the export of helium to “unfriendly” countries, highlighting the geopolitical issues surrounding the industry. In the past, helium was popularized, and the industry was supported by its military applications (filling dirigible aircraft, welding fighter jets and purging rocket engines). It also plays an important role in supporting present-day technologies (e.g., MRI machines and spectroscopy) and will also be important for a high-tech future (e.g., in quantum computing, fusion power, and space exploration). Shortages of helium will inevitably cause skyrocketing prices and consequently lead to significant challenges for research and development (as has happened in the past) and technological progress, as well as a slowdown in world economic growth and prosperity. Anticipated declines in natural gas production, associated with moves towards net-zero carbon emissions targets, make helium less accessible. While this is problematic for industry in the short term, it perhaps preserves some low entropy helium within the ground, making it more accessible to future generations. Given anticipated limitations to the future supply of helium, technological developments are currently focused on a few areas: the replacement of helium by other gases in industrial applications, changing technological approaches to not require helium, and reducing the cost of obtaining helium from the atmosphere. This paper explores the past, present and future of helium, focusing on the sustainability of the helium industry.

An Analysis of the Global EV Market: Sustainable Pathways to Net Zero Emissions

The rising urgency to address climate change has positioned electric vehicles (EVs) as a critical solution for achieving the United Nations' net-zero carbon emission targets. As human activities increase greenhouse gas emissions, the average global temperature continues to rise, leading to severe natural disasters in many regions. This situation underscores the urgent need to limit pollutant emissions and pursue sustainable resource management. This study analyzes the global EV market's trajectory towards sustainability, focusing on the interplay of policy frameworks and consumer engagement strategies in major EV markets, including the USA, the European Union, and China. The transition to EVs must be considered in conjunction with policy frameworks and the broader social environment. Using mixed methods and statistical models, we assess how different policies influence EV adoption and their alignment with sustainability goals. As the concept of sustainable development becomes more ingrained in society, it is promising that, through sustained policy implementation and resource development, the shift from ICE vehicles to EVs will make a crucial contribution to reducing carbon emissions. The findings provide actionable insights for optimizing policies and refining marketing strategies, offering a comprehensive blueprint for guiding the global EV market towards a sustainable future.

The impact of regional resources and technology availability on carbon dioxide removal potential in the United States

Abstract To achieve net zero carbon emissions by mid-century, the United States may need to rely on carbon dioxide removal (CDR) to offset emissions from difficult-to-decarbonize sectors and/or shortfalls in near-term mitigation efforts. CDR can be delivered using many approaches with different requirements for land, water, geologic carbon storage capacity, energy, and other resources. The availability of these resources varies by region in the U.S. suggesting that CDR deployment will be uneven across the country. Using the Global Change Analysis Model for the United States (GCAM-USA), we modeled six classes of CDR and explored their potential using four scenarios: a scenario where all the CDR pathways are available (Full Portfolio), a scenario with restricted geologic carbon storage (Low CCS), a scenario where the availability of bio-based CDR options is limited (Low Bio), and a scenario with constraints on enhanced rock weathering (ERW) capabilities (Low ERW). We find that by employing a diverse set of CDR approaches, the U.S. could remove between 1 and 1.9 GtCO2/yr by midcentury. In the Full Portfolio scenario, direct air carbon capture and storage (DACCS) predominates, delivering approximately 50% of CO2 removal, with bioenergy with carbon capture and storage (BECCS) contributing 25%, and ERW delivering 11.5%. Texas and the agricultural Midwest lead in CDR deployment due to their abundant agricultural land and geological storage availability. In the Low CCS scenario, reliance on DACCS decreases, easing pressure on energy systems but increasing pressure on the land. In all cases CDR deployment was found to drive important impacts on energy, land, or materials supply chains (for example for ERW) and these effects were generally more pronounced when fewer CDR technologies were available.

Exploring multimetal interactions between FeNi3 alloy and Lu3Ga5O12 metal oxide for improved water splitting performance

The production of energy from fossil fuels generates greenhouse gases, leading to global warming and various environmental impacts. Extensive research into sustainable alternative fuels has identified hydrogen (H2) as a viable option. With net zero carbon emissions, hydrogen presents a promising solution for sustainable and renewable energy. This study employs a simple gel-matrix method to fabricate Ni-Fe alloy-based nanocomposites in alkaline media (1 M KOH). Achieving outstanding performance in hydrogen generation through the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with impressive turn-over frequencies (TOF) of 2.98 s−1 at 177 mV and 1.48 s−1 at 219 mV. Nanocomposite’s unique structure enhances electroactive surface area (347.5 cm2/gram), extending electrocatalytic active sites and durability to 60 h. It shows excellent performance, characterized by low Tafel slopes of 50 mV/dec and 37 mV/dec, and minimal overpotentials of 219 mV for the oxygen evolution reaction (OER) and 177 mV for the hydrogen evolution reaction (HER), reaching a current density of 10 mA cm−2. This study presents a method for synthesizing high-performance, sustainable metal-alloy/garnet hybrid electrocatalysts, offering a new frontier in design of next-generation materials for advanced energy conversion technologies.

Impacts of a sustainable aviation fuel mandate on airline competition — Full-service carrier vs. low-cost carrier

The aviation industry has proposed the collective goal of achieving net-zero carbon emissions by 2050. In addition to the existing market-based methods (MBMs), the use of renewable energies, in particular, sustainable aviation fuel (SAF), could be one of the most promising means for achieving this long-term target. This paper investigates how an SAF mandate from the government can lead to heterogeneous impacts on two types of airlines, namely, full-service carriers (FSCs) and low-cost carriers (LCCs), that compete in the same markets. A game-theoretic economic model is constructed that accounts for the different service quality levels and cost structures (i.e., fuel efficiency) between FSCs and LCCs. Our analytical results suggest that the SAF mandate favors LCCs over FSCs. The share of SAF blended into fuel raises the airfares of both types of airlines while reducing the traffic and profit of FSCs. The impacts on the LCC traffic and profit depend on its fuel efficiency relative to that of FSC. When LCCs are sufficiently fuel efficient, the SAF mandate can increase their traffic and profit. The government subsidy on airline's SAF use is also analyzed, deriving the optimal subsidy levels for FSC and LCC respectively to achieve pareto-improvement in social welfare and consumer surplus. We also examine how air passengers’ environmental awareness affects the outcomes of SAF mandate implementation. Our economic model also accounts for passengers’ heterogeneous preferences in terms of service quality and price sensitivity.

Carbon Footprint Assessment Based on Agricultural Traceability System Records: A Case Study of Onion Production in Southern Taiwan

This study proposes an improved methodology based on life cycle assessment (LCA), which is used to calculate the carbon footprint of agriculture, provides a simple and feasible calculation path, and constructs a streamlined framework for calculating the carbon footprint based on the agricultural traceability system records. Using important economic crop (Onion) as research subject, and choose the largest planting area in R.O.C. (southern Taiwan) as a case study. A total of 64 farm production history records have been collected, includes all of farms certified with a traceable agricultural products (TAP) label. Through a detailed analysis of the traditional carbon footprint calculation method, found that agricultural traceability system records could replace the data source in carbon footprint verification (CFV) process, and system records could be used as activity data after being organized. With our method, no need to go through a complicated CFV process, just download the existing data on agricultural traceability system, can start calculating carbon footprint as soon as possible. To compared to traditional assessment method, results show a margin of error is less than 6% compared to traditional assessment methods. Advantages of improved method were be found, such as easy data acquisition, simplified calculation steps, and improved data transparency and accuracy. From statistical data, show that at least seven categories of carbon emission sources for carbon footprints, the most significant of carbon emission impact are fertilizers. The result of improved methodology based on life cycle assessment (LCA), show that using the improved methods can help promote the carbon footprint management efficiency of agricultural organizations such as Farmers’ Association or Agricultural Production Marketing Group, promptly monitor the carbon footprint status of their fields and adjust strategies to reduce carbon footprints in real-time, advancing towards the goal of net-zero carbon emissions.

An Examination of the Sustainability Activities of Global Airline Collaborations within the Scope of IATA's Sustainability Goals

This study aims to evaluate the sustainability activities of the global airline alliances Star Alliance, SkyTeam, and OneWorld within the framework of the International Air Transport Association's (IATA) sustainability goals. Specifically, it focuses on key areas such as achieving net-zero carbon emissions by 2050, promoting new aircraft technologies, enabling greener travel (in terms of noise and air quality), enhancing energy, resource, and operational efficiency, managing cabin waste and recycling, adopting sustainable aviation fuels (SAF), and protecting biodiversity. Using a content analysis methodology, data were gathered from publicly available sources, including airline sustainability reports, annual reports, and information from the IATA website. This systematic analysis provides an objective evaluation of how well these airline alliances are aligning their strategies with IATA’s sustainability goals. The findings reveal significant disparities in the alliances’ commitments. For instance, Star Alliance and OneWorld members exhibit deficiencies in biodiversity conservation, while SkyTeam members show slower progress towards achieving the net-zero carbon emissions target. Additionally, all three alliances demonstrate varying degrees of success in adopting SAF and implementing other sustainable practices, such as waste management and the promotion of new aircraft technologies. By identifying the strengths and weaknesses across the alliances, this research offers critical insights into how the aviation sector can more effectively contribute to global sustainability efforts.

Role of environmental, social, and governance (ESG) investment and natural capital stocks in achieving net-zero carbon emission

This study investigates the role of environmental, social, and governance (ESG) investment and natural capital stocks in achieving net-zero carbon emissions, focusing on the Chinese economy. This study uses the data from 2013 to 2022 and applies correlation analysis, quantile process estimation, quantile-factor augmented vector autoregressive, quantile dimension regression, and robustness analysis techniques. The results confirmed that ESG investment has a significant role in net-zero carbon emission and fosters natural capital stocks in the Chinese ecosystem. The results further established that natural capital stocks significantly benefit the Chinese ecosystem and reduce greenhouse gas emissions, CO2 emission – gaseous fuel, CO2 emission – solid fuel, and carbon intensity. Moreover, natural capital stocks have a significant role in achieving net-zero carbon emissions and it accelerates gross tree cover and green agricultural yield. The study is of great interest to corporations, Chinese banks, and the government in planning and achieving net-zero carbon emissions as per Prudential Financial regulation and accounting reporting systems. Achieving net-zero carbon emission is a process-based approach; therefore, the study recommends that policymakers customize investment mechanisms and natural capital accounting standards as per the territorial requirements and execute an ecological control system to make it sustainable.

Why path dependence leads to a fossilized Alberta: regionalism and the climate transition in Canada

ABSTRACT Canada is the world’s fourth largest producer of oil and fifth largest producer of natural gas. Yet, the country faces a ‘twin’ challenge in tackling the climate crisis. On the one hand, Canada’s federal climate goals state that it must achieve net-zero carbon emissions by 2050. On the other hand, regionalism stronghold in fossil-producing provinces lead to difficult trade-offs between an ambitious climate transition and reluctant actors supporting the fossil fuel industry. This situation is characterized as ‘fossilized’ petro-provinces by political scientist Angela Carter. This article explores how Alberta, Canada’s largest oil and natural gas producer, became fossilized. The article develops a path dependence argument organized around the role of regionalism in Alberta’s political development. Regionalism is a crucial persistent feature of Alberta to explain its fossilization because it influenced the formation of an interdependence between the government and the industry, a distinct political culture, and a conservative-led party system.

Multi-Fidelity Aeromechanical Design Framework for High Flow Speed Multistage Axial Compressors

Abstract The development of novel engine architectures is vital in achieving the aviation sector’s net-zero carbon emission target by 2050. With today’s digital decade providing support for an accelerated technology maturation, the challenge for turbomachinery design remains to significantly push the limits of current performance within an ambitious development lead time. In this context, it is essential to adopt a design framework where the predictive models or simulations employed target a sufficiently reliable performance assessment. These models must be tailored to the dynamics of evolving industrial design processes, and therefore continuously balance required design flexibility, robust evaluation, appropriate fidelity (i.e. the level of detail and accuracy they provide), and resulting evaluation time. This paper discusses a framework for designing axial compressors and its application to the aeromechanical optimisation of a high-speed compressor rotor. The design environment integrates geometry parametrisation, modular evaluation with different levels of fidelity for the aerodynamic and structural models, and surrogate-based optimisation (SBO) capabilities. It is shown how the combination of a modular sequencing of the different models and the acceleration enabled by high-performance computing (HPC) and machine learning allows for a more advanced preliminary design. A significant gain in isentropic efficiency is attained while satisfying all structural constraints. At the same time, it is demonstrated that the framework is compatible with the characteristics of the preliminary design phase: both in its ability to adapt to cycle and design changes as well as regarding the turnaround time of the optimisation itself.

Understanding human responses to air source heat pump noise: examining tonal changes and operating cycles

Air Source Heat Pumps are pivotal in the Government of the United Kingdom's target of achieving net zero carbon emissions by 2050. However, their widespread adoption faces challenges, with noise being among the main barriers to entry and a restricting factor at the planning stages. This study addresses concerns regarding noise propagation from outdoor units to indoor environments through a two-part experiment, aiming to capture human responses to Air Source Heat Pump noise based on the changes in the characteristics of noise emissions at various operating conditions, background noise levels, and source distances. The first part evaluates peoples' responses under static operating conditions to 20-second recordings, using the Self-Assessment Manikin scale and an annoyance scale. Following each recording, they used the Self-Assessment Manikin pictorial scale and an annoyance scale to report their response. In the second part, responses to transient Air Source Heat Pump operation cycles are assessed using 60-second recordings. Participants evaluated each recording at two points: after a transition in the operating cycle and at the end of the recording. The findings of the study provide insights into the human response to heat pump noise, essential for developing strategies to facilitate wider Air Source Heat Pump adoption.

Feasibility of Photonuclear Transmutation of Long-Lived Fission Products Extracted from Used Nuclear Fuel

To achieve the goal of net-zero carbon emission in energy production, nuclear power capacity and waste generation are expected to expand significantly in the next few decades. In the condition of continuous fuel recycling, long-lived fission products (LLFPs) are dominant contributors to the disposal impacts of nuclear waste. In this study, six LLFPs, including 99Tc, 129I, 135Cs, 126Sn, 93Zr, and 79Se, were identified as the primary contributors to more than 99% of long-term radiotoxicity of disposed nuclear waste across a wide range of fuel cycle scenarios. To reduce the amounts of LLFPs sent to geological repositories, the nuclear transmutation of LLFPs is being pursued. Specifically, this work systematically assessed the feasibility of transmuting LLFPs via photonuclear reactions. Photon transmutation is physically viable for the identified primary LLFPs except for 99Tc. For the five transmutable LLFPs, the achievable photon transmutation performance without isotopic separation was evaluated based on scoping calculations and consideration of nuclear data uncertainties. Using an extremely intense laser Compton photon source of 1019 γ /s, the effective transmutation half-life can be reduced to a few years. However, the absolute transmutation rates of LLFPs remain below 1 kg/yr. The energy required to power the photon source for transmuting all LLFPs produced in a nuclear reactor exceeds the net energy output of the reactor. Several potential strategies for improving photon transmutation performance were analyzed. None can substantially enhance the performance to make it practical for industrial applications.