Comparative life cycle assessment of integrated renewable energy-based power systems.

Integrated renewable-based power cycles should be employed to produce more sustainable electricity. This is a comparative life cycle assessment (LCA) of three combined power plants, encompassing: case 1 involving combined geothermal and wind, case 2 featuring combined geothermal and solar, and case 3 integrating wind and solar systems. The base case perovskite solar cell (PSC) modelling assumes a 3-year lifespan and a power conversion efficiency of 17 %. However, diverse scenarios are evaluated through a sensitivity assessment involving enhancements in lifetime and efficiency. The base case evaluation emphasizes that the phases with the most significant negative environmental effects which includes the drilling of geothermal wells, construction of wind plants, and manufacturing and installation of PSCs. The midpoint findings indicate that boosting the power conversion efficiency of PSC from 17 % to 35 % yields a notable decrease in environmental impact. Moreover, extending the lifetime from 3 to 15 years led to reduction in CO2 emissions from 0.0373 and 0.0185 kg CO2 eq/kWh to 0.026 and 0.0079 kg CO2 eq/kWh in cases 2 and 3, respectively. Assessing worst and best-case scenarios highlights significant declines in certain impact categories. In case 3, terrestrial ecotoxicity (TE), photochemical oxidant formation (POF), human toxicity (HT), marine ecotoxicity (ME), and marine eutrophication (MU) saw reductions exceeding 88 % compared to worst-case results. The environmental effects observed in cases 2 and 3 stem from toxicity and metal depletion, mainly linked to the PSC. Endpoint results revealed that when considering a PSC lifespan of 10 years or more, the detrimental ecosystem impacts of cases 2 and 3 become less severe than those of case 1. Uncertainty assessment has been done for different cases and impact categories. The study's results are also novel in which it evaluated the innovative PSC technology when integrated with other renewable resources, contrasting it with other integrated plants.

Heat pump supply chain environmental impact reduction to improve the UK energy sustainability, resiliency and security.

Various heat pump technologies are examined from an environmental perspective using a life cycle assessment approach. The investigated heat pump systems utilize air, ground, and water as their energy sources. Additionally, an innovative heat pump powered by green hydrogen is investigated in this study, to evaluate its environmental impacts and potential to commercialise on a large scale. A range of supply chain scenarios is explored, considering the main suppliers of the UK market. The reshoring heat pump industry and supply chain are evaluated to enhance energy resilience and security within the UK. The findings indicate that the hydrogen-based heat pump presents a promising option for the UK market, offering the advantages of reducing stress on the national grid network and minimizing the environmental impacts associated with the supply chain. Furthermore, a forecasting analysis is conducted based on the UK's net-zero emission plan to provide insight into future developments.

Evaluating sustainable development practices in a zero­carbon university campus: A pre and post-COVID-19 pandemic recovery study.

This paper aims to understand the critical areas for sustainable behavioural change on a university campus in order to achieve the net zero­carbon ambition pre- and post-COVID-19 pandemic recovery. For this purpose, the current empirical study is the first attempt to statistically examine the whole campus as a system, considering staff and student views (campus users), by developing an index measuring propensity for sustainable behavioural change to achieve a net zero­carbon campus. The novelty of this study is based on the following: (i) The impact of environmental sustainability measures due to COVID-19 is examined on three themes: physical activity routines on a daily basis, research, and teaching and learning, and (ii) the index that is compatible with quantifying the behavioural change. A multi-indicator questionnaire is used to collect empirical data for each of the three themes. Based on 630 responses, descriptive statistical analysis, normality tests, significance tests, and t-tests are performed using statistical and graphical software, and conducting uncertainty and sensitivity analyses on this quantitative data. The study found that 95 % of campus users agreed to use reusable materials on campus, and 74 % were willing to pay more for sustainable products. In addition, 88 % agreed to seek alternative and sustainable transportation for short research trips, while 71 % prioritised online conferences and project meetings for sustainable hybrid working. Moreover, the COVID-19 pandemic had a negative impact on the frequency of reusable material usage among campus users, as indicated by the index analysis, which showed a significant decrease from 0.8536 to 0.3921. The statistical findings show that campus users are more likely to initiate and endorse environmental sustainability measures in research and daily life than in teaching and learning, and there is no difference in their propensity for change. This research provides net zero­carbon sustainability researchers and leaders with a crucial baseline for scientific advances in the sustainability field. It also offers practical guidelines for implementing a net zero­carbon campus, engaging users from various disciplines, which has important implications and contributions.

Identification of 'carbon hot-spots' and quantification of GHG intensities in the biodiesel supply chain using hybrid LCA and structural path analysis.

It is expected that biodiesel production in the EU will remain the dominant contributor as part of a 10% minimum binding target for biofuel in transportation fuel by 2020 within the 20% renewable energy target in the overall EU energy mix. Life cycle assessments (LCA) of biodiesel to evaluate its environmental impacts have, however, remained questionable, mainly because of the adoption of a traditional process analysis approach resulting in system boundary truncation and because of issues regarding the impacts of land use change and N(2)O emissions from fertilizer application. In this study, a hybrid LCA methodology is used to evaluate the life cycle CO(2) equivalent emissions of rape methyl ester (RME) biodiesel. The methodology uses input-output analysis to estimate upstream indirect emissions in order to complement traditional process LCA in a hybrid framework. It was estimated that traditional LCA accounted for 2.7 kg CO(2)-eq per kg of RME or 36.6% of total life cycle emissions of the RME supply chin. Further to the inclusion of upstream indirect impacts in the LCA system (which accounted for 23% of the total life cycle emissions), emissions due to direct land use change (6%) and indirect land use change (16.5%) and N(2)O emissions from fertilizer applications (17.9%) were also calculated. Structural path analysis is used to decompose upstream indirect emissions paths of the biodiesel supply chain in order to identify, quantify, and rank high carbon emissions paths or 'hot-spots' in the biodiesel supply chain. It was shown, for instance, that inputs from the 'Other Chemical Products' sector (identified as phosphoric acid, H(3)PO(4)) into the biodiesel production process represented the highest carbon emission path (or hot-spot) with 5.35% of total upstream indirect emissions of the RME biodiesel supply chain.