• Energy Research
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Recent biodiversity–ecosystem functioning experiments in temperate grasslands have shown that productivity positively correlates with plant species richness. Resource partitioning (in particular, nitrogen [N] partitioning) has been proposed as one possible mechanism to explain this pattern. There is evidence for interspecific differences in chemical form, soil depth, and timing of N uptake. However, it has rarely been tested whether such differences result in increased N exploitation at the plant community level. Using 15N‐labeled litter that was mixed into different soil layers, we tested whether eight common grasses and forbs grown in communities of one, two, or four species differ with respect to the proportions of N taken up from different soil depths (N niche), and how this affects the total N uptake of plant communities. We calculated proportional similarity between species (niche overlap) with regard to N uptake from the labeled soil layers; we further calculated an a priori measure of community N uptake based on species N uptake in monoculture (community niche). Interestingly, however, plant community N uptake was not affected by species richness, possibly because community‐level N uptake was determined by (diversity‐independent) soil N mineralization rates. We nevertheless observed a positive effect of species richness on productivity due to increased aboveground biomass : N ratios. This may indicate increased competition for light, resulting in increased amounts of comparably N‐poor stem tissue. However, community N content and biomass were positively correlated with the community niche, a measure which is strongly linked to species composition. Thus, our results suggest that the studied species are generalists rather than specialists regarding N uptake depth, and that species composition was more important than species richness in determining community N uptake. Overall, N partitioning may be a less important driver of positive biodiversity–productivity effects in temperate grasslands than previously assumed.

In 2012, heavy rainfall resulted in flooding and devastating impacts across West Africa. With many people highly vulnerable to such events in this region, this study investigates whether anthropogenic climate change has influenced such heavy precipitation events. We use a probabilistic event attribution approach to assess the contribution of anthropogenic greenhouse gas emissions, by comparing the probability of such an event occurring in climate model simulations with all known climate forcings to those where natural forcings only are simulated. An ensemble of simulations from 10 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) is compared to two much larger ensembles of atmosphere-only simulations, from the Met Office model HadGEM3-A and from climateprediction.net (a regional version of HadAM3P). These are used to assess whether the choice of model ensemble influences the attribution statement that can be made. Results show that anthropogenic greenhouse gas emissions have decreased the probability of high precipitation across most of the model ensembles, although the magnitude and confidence intervals of the decrease depend on the ensemble used, with more certainty in the atmosphere-only model ensembles. An increase in probability of high precipitation in HadGEM3-A using the observed trend in SSTs for natural simulations highlights the need to ensure that estimates of natural SSTs are consistent with observed trends in order for results to be robust. Further work is needed to establish how anthropogenic forcings are affecting the rainfall processes in these simulations in order to better understand the differences in the overall effect.

Abstract Despite a series of transport decarbonisation initiatives, transport carbon emissions have been growing in both absolute and relative terms since 1990, and this is contributing to climate change. This study scrutinises the decoupling experiences of transport carbon emissions in 16 selected countries, including both developed and developing countries, over a 29-year timeframe (1990–2018). Resting upon the concept of socio-ecological resilience, collaborative planning and policy-implementation gap, a new conceptual framework is proposed to understand transport decarbonisation policies. In doing so, data of transport carbon emissions and Real Gross National Income in Purchasing Power Parity (based 2017) are first analysed. Progress of decoupling is then categorized for each country in every five-year period (a total of 96 data points). We then select consecutive periods when a country moves towards absolute decoupling (i.e. improvement) or deviates from it (i.e. worsening) and identify relevant policy instruments implemented based on a nine-component strategic framework that addresses the policy-implementation gap. Results indicate that defining clear sectoral objectives in action plans and integrating a holistic policy package to reinforce sustainable transport is pivotal. While there are no magic bullets to achieve transport decarbonisation, the strategic framework can help enhance policy effectiveness by formulating context-specific strategies.

In this paper we investigate household electricity use, electric vehicle (EV) home-charging and distributed photovoltaic (PV) power production in a case study for the city of Westminster, London. Since it is economically beneficial to maximize PV power self-consumption in the UK context the power consumption/production patterns with/without introducing EV home-charging on the household level is investigated. Additionally, since this might have an effect on the electricity use on an aggregate of households a large-scale introduction of EV charging and PV power production in the entire city of Westminster is also investigated. Household electricity consumption and EV home-charging are modeled with a Markov-chain model. PV power production is estimated from solar irradiation data from Meteonorm for the location of Westminster combined with a model for photovoltaic power production on tilted planes. The available rooftop area is estimated from the UK map geographic information database. EV home-charging increases the household electricity use mainly during evening with a maximum during winter whereas PV produces power during daytime with maximum during summer. On the household level this mismatch introduces variability in power consumption/production, which is shown to be less prominent for the large-scale scenario of the entire city of Westminster.

This thesis shows how the Process Analysis Method (PAM) can be applied to assess technologies used to mitigate arsenic from drinking water in rural India, using a set of sustainability indicators. Stakeholder perspectives, gathered from a fieldwork survey of 933 households in West Bengal in 2012, played a significant role in this assessment. This research found that the ‘Most Important’ issues as specified by the technology users are cost, trust, distance from their home to the clean water source (an indicator of convenience), and understanding the health effects of arsenic. It was also found that none of the ten technologies evaluated are economically viable, as many do not charge user-fees, which creates reliance upon donations to meet recurring costs. Utilisation of a technology is strongly related to sociocultural capital, but in many cases, features that contribute to sociocultural value, like regular testing of the treated water, are not included in the financial budget. It is suggested that increased awareness might change attitudes to arsenic-rich waste and its disposal protocols. This waste is often currently discarded in an uncontrolled manner in the local environment, giving rise to the possibility of point-source recontamination. All technologies proved to have difficulties in dealing with waste, except the Tipot and Dug wells which produce no waste. Of the methods considered, the BESU technology scored highest, but still only with 47-62% of the maximum scores achievable within each domain. This explains the widespread failure of mitigation projects across the region. The indicators and metrics show where improvements can be made. A model scheme based on these findings is outlined which could be applied with the objective of increasing utilisation and improving sustainability. It can be concluded that a product stewardship approach should be taken in regard to design, implementation and operation of the technologies, including the creation of a regulated toxic waste collection and disposal industry.

Abstract This paper concentrates on ‘middles’ and ‘middle actors’ in energy systems and introduces a “middle-out” framework for examining and supporting systemic change to a lower carbon society. We propose this “middle-out” approach as a complement to “top-down” and “bottom-up” strategies. Our approach suggests that two essential elements for successful systemic change are actors’ agency and capacity, where ‘agency’ refers to actors’ abilities to make their own free choices, and ‘capacity’ refers to actors’ abilities to perform the choices they made. We argue that due to their position between top and bottom actors and between technology and implementation, middle actors play crucial functions in the transition process. Their abilities are based to their own agency and capacity which they can exercise to influence the agency and/or capacity of other actors. The paper discusses middle actors vis-a-vis ‘intermediaries’ and demonstrates the value of the middle-out approach. Through elaborated examples of three middle actors – congregations, building professionals, and commercial building communities – it shows how middles exert influence upstream (to top actors), downstream (to bottom actors) and sideways (to other middle actors) through mediating, enabling and aggregating both themselves and others. A few weaknesses of this approach are discussed as well.

Space-heating accounts for more than 40% of residential energy consumption in some countries (e.g. the UK and the US) and thus is a key area to address for energy efficiency improvement. To do so, ...

Hydroelectricity provides approximately 65% of Brazil’s power generating capacity, making the country vulnerable to droughts, which are becoming increasingly frequent. Current energy law and policy responses to the problem rely on a sectorial approach and prioritise energy security and market regulation. Brazil has opted to increase energy security levels during periods of hydrological variability with national grid interconnection and thermal plants backup. Additionally, Brazil has created the Energy Reallocation Mechanism (MRE) to manage the generators’ financial impacts in times of insufficient water. This policy, however, was unable to avoid the high financial exposure of generators in the spot market during the severe droughts experienced in the period 2013-2017. To explore how a more diversified electricity matrix can contribute to reducing hydrological risk, this article uses Integrated Assessment Modelling (IAM) techniques to analyse future macroeconomic and energy scenarios for Brazil in a global context, aligned with the Brazilian Nationally Determined Contributions (NDC) under the 2015 Paris Agreement on Climate Change. We show that the addition of non-hydro renewables is an advantage from the integrated Water-Energy-Food nexus perspective because it reduces trade-offs amongst the water and energy sectors. Our conclusions suggest that a nexus perspective can provide useful insights on how to design energy laws and policies.