Joint use of attribute importance rankings and non-attendance data in choice experiments

The joint and alternative uses of attribute non-attendance and importance ranking data within discrete choice experiments are investigated using data from Lebanon examining consumers’ preferences for safety certification in food. We find that both types of information; attribute non-attendance and importance rankings, improve estimates of respondent utility. We introduce a method of integrating both types of information simultaneously and find that this outperforms models where either importance ranking or non-attendance data are used alone. As in previous studies, stated non-attendance of attributes was not found to be consistent with respondents having zero marginal utility for those attribute

Energy self-sufficiency, grid demand variability and consumer costs: Integrating solar PV, Stirling engine CHP and battery storage

Global uptake of solar PV has risen significantly over the past four years, motivated by increased economic feasibility and the desire for electricity self-sufficiency. However, significant uptake of solar PV could cause grid balancing issues. A system comprising Stirling engine combined heat and power, solar PV and battery storage (SECHP-PV-battery) may further improve self-sufficiency, satisfying both heat and electricity demand as well as mitigating potential negative grid effects. This paper presents the results of a simulation of 30 households with different energy demand profiles using this system, in order to determine: the degree of household electricity self-sufficiency achieved; resultant grid demand profiles; and the consumer economic costs and benefits. The results indicate that, even though PV and SECHP collectively produced 30% more electricity than the average demand of 3300. kWh/yr, households still had to import 28% of their electricity demand from the grid with a 6. kWh battery. This work shows that SECHP is much more effective in increasing self-sufficiency than PV, with the households consuming on average 49% of electricity generated (not including battery contribution), compared to 28% for PV. The addition of a 6. kWh battery to PV and SECHP improves the grid demand profile by 28% in terms of grid demand ramp-up requirement and 40% for ramp-downs. However, the variability of the grid demand profile is still greater than for the conventional system comprising a standard gas boiler and electricity from the grid. These moderate improvements must be weighed against the consumer cost: with current incentives, the system is only financially beneficial for households with high electricity demand (<4300. kWh/yr). A capital grant of 24% of the installed cost of the whole micro-generation system is required to make the system financially viable for households with an average electricity demand (3300. kWh/yr)

Life cycle environmental impacts of natural gas drivetrains used in UK road freighting and impacts to UK emission targets

Using natural gas as a fuel in the road freight sector instead of diesel could cut greenhouse gas and air quality emissions but the switch alone is not enough to meet UK climate targets. A life cycle assessment (LCA) has been conducted comparing natural gas trucks to diesel, biodiesel, dimethyl ether and electric trucks on impacts to climate change, land use change, air quality, human health and resource depletion. This is the first LCA to consider a full suite of environmental impacts and is the first study to estimate what impact natural gas could have on reducing emissions form the UK freight sector. If LNG is used, climate change impacts could be up to 33% lower per km and up to 12% lower per kWh engine output. However, methane emissions will eliminate any benefits if they exceed 1.5–3.5% of throughput for typical fuel consumption. For non-climate impacts, natural gas exhibits lower emissions (11–66%) than diesel for all indicators. Thus, for natural gas climate benefits are modest. However, emissions of CO, methane and particulate matter are over air quality limits set for UK trucks. Of the other options, electric and biodiesel trucks perform best in climate change, but are the worst with respect to land use change (which could have significant impacts on overall climate change benefits), air quality, human toxicity and metals depletion indicators. Natural gas could help reduce the sector's emissions but deeper decarbonization options are required to meet 2030 climate targets, thus the window for beneficial utilisation is short

Methane regulation in the EU: Stakeholder perspectives on MRV and emissions reductions

Published online 19 September 2022Methane is potent greenhouse gas (GHG) accounting for 11% of all EU emissions, but in contrast to CO2 it has received relatively little attention. Although methane is regulated under the EU Effort Sharing framework, this policy lacks methane-specific regulations or targets, leaving the Member States considerable discretion over whether to prioritize methane reduction or not. The European Commission presented a proposal for EU methane regulation on 15 December 2021. However, our understanding of how to design measurement, reporting and verification (MRV) regulation for methane is limited. MRV involves many stakeholders at different steps in the process (policymakers, industry, civil society, MRV service providers, etc.), whose perspectives may differ, and our study aims to gain an insight into what constitutes an effective MRV by garnering the different stakeholders’ perspectives. The study reveals that: (1) the limits of voluntary MRV initiatives justify regulatory intervention, (2) the major barrier to the implementation of methane-specific MRV is not economic, but relates to an incomplete understanding of methane sources and available measurement technologies, (3) verification is likely to be the most challenging MRV element to implement, partly due to the limited number of accredited verifiers and overlapping tasks (4) MRV needs to be accompanied by methane mitigation policies incentivising continuous improvement of companies’ performance. The study recommends enhancing the proposed regulation by: introducing equal requirements for operated and non-operated assets; an obligation to report measurement uncertainties; a closer integration of MRV and LDAR; clear verification rules; and an introduction of minimum and optimum methane control standards

How to decarbonise international shipping: Options for fuels, technologies and policies

International shipping provides 80–90% of global trade, but strict environmental regulations around NOX, SOX and greenhouse gas (GHG) emissions are set to cause major technological shifts. The pathway to achieving the international target of 50% GHG reduction by 2050 is unclear, but numerous promising options exist. This study provides a holistic assessment of these options and their combined potential to decarbonise international shipping, from a technology, environmental and policy perspective. Liquefied natural gas (LNG) is reaching mainstream and provides 20–30% CO2 reductions whilst minimising SOX and other emissions. Costs are favourable, but GHG benefits are reduced by methane slip, which varies across engine types. Biofuels, hydrogen, nuclear and carbon capture and storage (CCS) could all decarbonise much further, but each faces significant barriers around their economics, resource potentials and public acceptability. Regarding efficiency measures, considerable fuel and GHG savings could be attained by slow-steaming, ship design changes and utilising renewable resources. There is clearly no single route and a multifaceted response is required for deep decarbonisation. The scale of this challenge is explored by estimating the combined decarbonisation potential of multiple options. Achieving 50% decarbonisation with LNG or electric propulsion would likely require 4 or more complementary efficiency measures to be applied simultaneously. Broadly, larger GHG reductions require stronger policy and may differentiate between short- and long-term approaches. With LNG being economically feasible and offering moderate environmental benefits, this may have short-term promise with minor policy intervention. Longer term, deeper decarbonisation will require strong financial incentives. Lowest-cost policy options should be fuel- or technology-agnostic, internationally applied and will require action now to ensure targets are met by 2050

Modelling gender perception of quality in interurban bus services

This paper models how women and men perceive the quality of interurban bus services and proposes a new methodology for detecting the highest priority service variables to act on. Service quality perception was modelled using both ordered logit and ordered probit models using data from revealed preference surveys. The methodology for detecting different priority levels uses the graphic representation of the relationships between influence in the model and average evaluation by users. The modification of certain variables increases the knowledge of how woman evaluate quality in bus services to help promote the use of interurban public transport. Statistical analysis of the data provides some conclusions such as: the proportion of users increases as age decreases for both men and women; and women seem to make shorter and more frequent trips than men. The best model for this data set was ordered logit. As expected, the most relevant variable is the relationship between quality and price. Other important variables are the condition of the bus and the frequency of service

Organic waste to energy: Resource potential and barriers to uptake in Chile

Achieving net-zero greenhouse gas emissions by 2050 requires a step-change in resource management, and the utilisation of organic waste is currently an untapped opportunity in Latin America. This study carries out a quantitative and qualitative assessment of organic waste-to-energy potentials for the Chilean context. First, it produces a comprehensive quantification of organic waste, including annual crop residues, horticulture residues, livestock manure and OFMSW by region; then it estimates the energy potential of these bioresources; and finally, it conducts a series of stakeholder interviews determining barriers to greater waste-to-energy utilisation. The results show that the total bioenergy potential from waste is estimated at 78 PJ/yr (3.3% of annual energy demand), being livestock manure (41%) and annual crop residues (28%) the main sources, arising mostly from three regions. The stakeholder elicitation concluded that financial, technical, and institutional barriers prevent waste utilisation, highlighting the needs to address elevated investment costs and high reliance on landfilling practices, which together with public policies could enable the full exploitation of these resources to ensure energy security and resource efficiency.This research was supported by the Sustainable Gas Institute at Imperial College London and by Universidad de Santiago de Chile through the DICYT (Dirección de Investigación Científica y Tecnológica) grant 021812GL. X. Schmidt Rivera is supported by the Institutional QR Global Challenges Research Fund. F. Jalil-Vega acknowledges the support of ANID through Complex Engineering Systems Institute PIA/BASAL AFB180003, and through ANID/FONDAP/15110019 SERC-Chile