• Energy Research

In the 21st century the carbon emissions, material consumption, and impact on planetary boundaries associated with clothing have increased dramatically, driven in large part by fast fashion. The UK represents a typical, affluent, import-reliant Global North country, with clothing consumption per capita at double the global average and the impacts largely offshored. Progress towards a sustainable, circular clothing economy in the UK has been sluggish, as it has been globally. Here, we develop scenarios exploring how, over the coming two decades, the UK clothing economy could achieve the ambitious reductions in environmental impacts necessary to bring humanity's impact back within planetary boundaries. The scenarios consider the impacts of production- and consumption-focused changes, and the modelling uses material flow analysis to develop an assessment of energy consumption, carbon emissions, water consumption, and land use. We find that cleaner production and recycling alone could provide significant benefits for land and water use, reducing footprints by 60–70% by 2040. But to meaningfully reduce energy use, transformational changes will be required throughout supply chains at consumer and post-consumer stages. The same is true if the UK clothing economy is to be on track for net-zero by 2050, which requires these changes to be well under way within the next decade in order to halve emissions. Given the scale of change required, it seems highly unlikely that current clothing business models are compatible with a sustainable future.

Here we investigate the increasingly complex relationship between the resource recovery practices of the UK concrete industry and ongoing low-carbon transitions taking place in electricity and steel. Reductions in UK coal-based electricity and primary steel production are reducing domestic availability of residues – coal ash and steel slag – that are used to replace cement in concrete; for decarbonisation purposes and to increase concrete quality. This is leading to an unusual mass-transportation of ‘wastes’ from the Global South to Global North. Focusing closely upon the mitigation pathways of concrete producers, we develop an inter-industry model of material flows, and a diversity of scenarios and sensitivity tests, to consider how resource recovery practices and carbon emissions of the three sectors may evolve. A continuation of domestic shortages in waste-derived cement substitutes appears inevitable and future international shortages possible. But even if foreign producers supplied enough cement substitutes to meet UK demand, the broader carbon implications of such trade may be far from benign. Using a revenue-based approach to allocate emissions to coal ash leads to a wide range of embodied carbon estimates – from relatively low (0.15 t.CO₂/t.ash) to exceeding that of traditional Portland cement (1 t.CO₂/t.ash). However, the carbon associated with internationally traded recovered resources currently stands behind a ‘double-blind’ system of accounting: emissions do not register in the conventional territorial accounts of the importing country and they may be hidden from its consumption-based accounts as well. The impacts of such trade and related carbon accounting conventions are unclear and we emphasise the need for further investigation. To this end, our results demonstrate the importance of incorporating highly interconnected sectors and international trade into analyses of low-carbon transitions, and highlight the challenges this presents for designing appropriate policies, accounting frameworks, and interdisciplinary impact assessment methods that look beyond sectorial and national horizons.

Small-scale wind turbine operations within the urban environment are exposed to high levels of gusts and turbulence compared to flows over less rough surfaces. There is therefore a need for such systems to not only cope with, but to thrive under such fluctuating flow conditions. This paper addresses the potential importance of gust tracking technologies within the urban environment via the analysis of the additional energy present in the gusty wind resource using high resolution measurements at two urban roof-top locations. Results demonstrate significant additional energy present in the gusty wind resource at high temporal resolution. This energy is usually under-represented by the use of mean wind speeds in quantifying the power in the wind over longer averaging times. The results support the promise of capturing a portion of this extra energy through gust tracking solutions. The sensitivity of this “additional” wind energy to averaging time interval is also explored, providing useful information for the design of gust tracking or dynamic control algorithms for small-scale turbines. Relationships between turbulence intensity and excess energy available are drawn. Thus, an analytical model is proposed which may prove useful in predicting the excess energy available across wide areas from, for example, boundary layer turbulence models.

The IEA has estimated that over the next four decades US$31 trillion will be required to promote energy efficiency in buildings. However, the opportunities to make such investments are often constrained, particularly in contexts of austerity. We consider the potential of revolving funds as an innovative financing mechanism that could reduce investment requirements and enhance investment impacts by recovering and reinvesting some of the savings generated by early investments. Such funds have been created in various contexts, but there has never been a formal academic evaluation of their potential to contribute to low carbon transitions. To address this, we propose a generic revolving fund model and apply it using data on the costs and benefits of domestic sector retrofit in the UK. We find that a revolving fund could reduce the costs of domestic sector retrofit in the UK by 26%, or £9 billion, whilst also making such a scheme cost-neutral, albeit with significant up-front investments that would only pay for themselves over an extended period of time. We conclude that revolving funds could enable countries with limited resources to invest more heavily and more effectively in low carbon development, even in contexts of austerity.

ABSTRACTThe predictability of above roof wind resource (three‐dimensional mean wind speed) in the roughness and inertial sublayers over idealized urban arrays has been studied using data previously obtained from wind tunnel experiments and a validated large eddy simulation. Both uniform arrays and arrays of heterogeneous heights (representing suburban and more complex urban areas, respectively) were considered. Firstly, the spatial variation of the wind resource within the roughness sublayers over the more complex heterogeneous array was assessed, and suggestions for ideal rooftop turbine placement in this type of geometry were made. It was found that the spatially averaged wind profile can be considered to be a lower bound for the available wind resource at the most viable turbine locations. Secondly, available methods of estimating spatially averaged wind profiles above urban‐like surfaces were discussed, and bearing in mind the uncertainties inherent in these methods, a typical wind resource prediction methodology was followed. Significant uncertainties were found to occur at each stage of the prediction, but it was found that the errors occurring because of the typical methods used to parameterize surface aerodynamics are potentially the most significant. Therefore, to increase the accuracy of these prediction methodologies, it is necessary to improve the methods of parameterizing surface aerodynamics and estimating roughness sublayers spatial averages for urban‐like surfaces. Copyright © 2011 John Wiley & Sons, Ltd.

AbstractEconomic inequality and climate change are pressing issues that have climbed high up the political agenda, yet action to mitigate both remains slow. As income is a key determinant of ecological impacts, the Global North—and wealthier classes elsewhere—are the primary drivers of global carbon emissions, while the least well off have contributed the least yet are set to be hit hardest by climate impacts. These inequalities are clearly unjust, but the interrelations between economic inequality and ecological impacts are complex, leaving open the question of whether reducing the former would mitigate the latter, in the absence of reductions in total economic output. Here, we contribute to these debates by estimating the carbon-footprint implications of reducing income (and hence expenditure) inequalities within 32 countries of the Global North to the levels people consider to befair; levels that are substantially smaller than currently exist. We find that realising these levels of economic inequality brings comparable reductions in carbon-footprint inequalities. However, in isolation, implementingfairinequalities has a negligible impact upon total emissions. In contrast, recomposing consumption—by reducing inequalities in household expenditure and the overall levels, then reallocating the reductions to public services—reduces carbon footprint by up to 30% in individual countries and 16% overall and, crucially, still allows the consumption of those at the bottom to rise. Such reductions could be significant on a global level, and they would be additional to the full range of conventional technological and demand-side measures to reduce carbon emissions.

The transition from coal-based electricity to ‘carbon neutral’ biofuels derived from forests has catalysed a debate largely centred upon whether woody-biofuels drive deforestation. Consequently, a crucial point is often missed. Most wood pellets used in electricity production are derived from waste-wood; a practice considered acceptable by many otherwise strongly opposed to the industry. We highlight that, precisely because waste-wood is a ‘waste’, its carbon-neutral credentials should be questioned. We then examine a parallel development occurring within the same industrial system; the recovery of electricity producers’ combustion-ash residues for concrete production. Contrasting how accounting practices allocate upstream carbon to these ‘wastes’ in the cases of wood pellets and coal-ash reveals how decisions are shaped by industry imperatives, rather than established lifecycle techniques. If the politics of emissions allocation continue to evolve in this way, it may become increasingly difficult to distinguish where progress towards a low-carbon, environmentally sustainable and circular economy is real, from where it is an artefact of biased and inconsistent accounting practices.