• Energy Research

Buildings account for over one-third of global emissions and energy use. Meeting climate pledges will require achieving high operational energy efficiency with low embodied impacts in new construction. Yet, a systematic identification of the relative influence of building design parameters on both operational and embodied efficiencies has rarely been attempted. In this paper we explore for the first time the sensitivity of a wide range of design and operation parameters in terms of embodied carbon, construction cost, as well as heating and cooling loads for multi-storey buildings. We devised a model to estimate the relative importance of a large set of input variables, describing a building’s shape, size, layout, structure, ventilation, windows, insulation, air, and use for residential and office multi-storey buildings, across different climates. We found that increasing building compactness, using steel or timber instead of concrete frames, lowering window-to-wall ratio, choosing the most suitable glazing, and employing mechanical ventilation with heat recovery are the most important measures to decrease embodied emissions and operational energy. The most significant trade-offs with construction cost were found for the choice of frame material and in the decision whether to install mechanical ventilation. We estimate that 28–44% of yearly heating and cooling energy and 6 Gt cumulative embodied CO2e until 2050 could be saved in multi-storey buildings, without employing new technologies.

We use the societal exergy analysis to identify periods and factors controlling efficiency dilution and carbon deepening of electricity in Portugal from 1900 to 2014. Besides estimating the carbon intensity of electricity production, we propose a new indicator, the carbon intensity of electricity use, which quantifies CO2/kWh of electricity derived useful exergy. Results show final to useful efficiency dilution until World War I (50% to 30%) due to a decrease in share of the high-efficiency transport sector and from mid-1940s to 1960 and mid-1990s onwards (58% to 47% and 47% to 40%) due to an increase in share of the low efficiency commercial and residential sector. Decarbonization from 1900 to mid-1960s, with carbon intensities of electricity production and use dropping respectively from 12.8 to 0.2 and from 33.6 to 0.4 kg CO2/kWh due to an increase in thermoelectricity efficiencies and an increase in share of hydro. Then, a period of carbon deepening until 1990 with carbon intensities tripling due to a shift in shares from hydro to thermoelectricity and more recently a period of decarbonization with carbon intensities decreasing to 0.35 and 0.9 kg CO2/kWh, due to the increase in renewable electricity despite a dilution in final to useful efficiency.

Understanding the size and spatial distribution of material stocks is crucial for sustainable resource 22 management and climate change mitigation. This study presents high-resolution maps of buildings and 23 mobility infrastructure stocks for the United Kingdom (UK) and the Republic of Ireland (IRL) at 10 24 meters, combining satellite-based Earth observations, OpenStreetMaps, and material intensities 25 research. Stocks in the UK and IRL amount to 19.8 Gigatons or 279 tons/cap, predominantly aggregate, 26 concrete and bricks, as well as various metals and timber. Building stocks per capita are surprisingly 27 similar across medium to high population density, with only the lowest population densities having 28 substantially larger per capita stocks. Infrastructure stocks per capita decrease with higher population 29 density. Interestingly, for a given building stock within an area, infrastructure stocks are substantially 30 larger in IRL than in the UK. These maps can provide useful insights for sustainable urban planning and 31 advancing a circular economy.

This dataset resulted from processing UK trade statistics provided by PRODCOM. It contains the input data for the Material Flow Analysis of plastics in the UK, the output plastic data flows for various stations of the UK plastics supply chain, and the code used to process it.

Abstract Heat recovery plays an important role in energy saving in the supply chain of steel products. Almost all high temperature outputs in the steel industry have their thermal energy exchanged to preheat inputs to the process. Despite the widespread development of heat recovery technologies within process stages (process heat recovery), larger savings may be obtained by using a wider integrated network of heat exchange across various processes along the supply chain (integrated heat recovery). Previous pinch analyses have been applied to optimise integrated heat recovery systems in steel plants, although a comparison between standard process heat recovery and integrated heat recovery has not yet been explored. In this paper, the potential for additional energy savings achieved by using integrated heat recovery is estimated for a typical integrated steel plant, using pinch analysis. Overall, process heat recovery saves approximately 1.8 GJ per tonne of hot rolled steel (GJ/t hrs), integrated heat recovery with conventional heat exchange could save 2.5 GJ/t hrs, and an alternative heat exchange that also recovers energy from hot steel could save 3.0 GJ/t hrs. In developing these networks, general heat recovery strategies are identified that may be applied more widely to all primary steel production to enhance heat recovery. Limited additional savings may be obtained from the integration of the steel supply chain with other industries.

Decarbonization of all sectors is needed to mitigate the impacts of climate change. To accomplish this, hydrogen use has been suggested in many industries that currently rely on fossil fuels. Yet, the emissions intensity of hydrogen depends on how it is produced and distributed. Additionally, it is unclear whether hydrogen use leads to a reduction in GHG emissions compared to alternative decarbonization options such as electrification with renewables. Here, we systematically compare the decarbonisation potential of supplying hydrogen to the United Kingdom from a wide range of global supply chains. We do this by assessing 37,000 configurations of the hydrogen supply chain from primary energy production through to end-use. We find that imports of green hydrogen production are unlikely to be compatible with the UK Low Carbon Hydrogen Standard. The maximum mitigation potential is achieved when electrification is prioritized, and hydrogen used only for applications where electrification is not viable. This leads to a reduction of up to 280 Mt CO(2)e/a across all sectors considered in the UK. In the short term, use of domestic green hydrogen infrastructure should focus on displacing existing gray hydrogen use.

Food security relies on nitrogen fertilisers, but its production and use account for approximately 5% of global greenhouse gas (GHG) emissions. Meeting climate change targets requires the identification and prioritisation of interventions across the whole lifecycle of fertilisers. Here, we have mapped the global flows of synthetic nitrogen fertilisers and manure, and their corresponding GHG emissions across their lifecycle. We have then explored the maximum mitigation potential of various interventions to reduce emissions by 2050. We found that approximately two thirds of fertiliser emissions take place after their deployment in croplands. Increasing nitrogen use efficiency is the single most effective strategy to reduce emissions. Yet, this should be combined with decarbonisation of fertiliser production. Using currently available technologies, GHG emissions of fertilisers could be reduced up to approximately one fifth of current levels by 2050.

Meeting climate targets requires profound transformations in the energy system. Most energy uses should be electrified, but where this is not feasible, hydrogen can be part of the solution. However, 98% of global hydrogen production involves greenhouse gas emissions, with an average of 12 kg CO2e/kg H2. Therefore, new hydrogen production pathways are needed in order to make hydrogen production compatible with climate targets. In this work, we fill this gap by systematically comparing the energy and emissions intensity of 173 hydrogen production pathways suitable for the UK. Scenarios include onshore and offshore pathways and the use of repurposed infrastructure. Unlike fossil-fuel based pathways, the results show that electrolytic hydrogen powered by fixed offshore wind could align with proposed emissions standards, either onshore or offshore. However, the embodied and fugitive emissions are important to consider for electrolytic pathways as they result in 10–50% of the total emissions intensity.