Journal: Energy & Environmental Science

Abbreviation

Energy Environ. Sci.

Publisher

Royal Society of Chemistry

Journal Volumes

ISSN

1754-5692
1754-5706

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2010 - 2019492020 - 202526
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Publications 1 - 10 of 75
  • The carbon footprint of the carbon feedstock CO2
    Item type: Journal Article
    Müller, Leonard J.; Kätelhön, Arne; Bringezu, Stefan; et al. (2020)
    Energy & Environmental Science
    Capturing and utilizing CO2 as carbon feedstock for chemicals, fuels, or polymers is frequently discussed to replace fossil carbon and thereby help mitigate climate change. Emission reductions by Carbon Capture and Utilization (CCU) depend strongly on the choice of the CO2 source because CO2 sources differ in CO2 concentration and the resulting energy demand for capture. From a climate-change perspective, CO2 should be captured at the CO2 source with the lowest CO2 emissions from capture. However, reported carbon footprints differ widely for CO2 captured, from strongly negative to strongly positive for the same source. The differences are due to methodological ambiguity in the treatment of multifunctionality in current assessment practice. This paper reviews methodological approaches for determining the carbon footprint of captured CO2 as carbon feedstock, and shows why some approaches lead to suboptimal choices of CO2 sources and that increased consistency in life cycle assessment (LCA) studies on CCU is needed. Based on strict application of Life Cycle Assessment (LCA) standards and guidelines, it is shown that substitution should be applied to avoid suboptimal choices of CO2 sources. The resulting methodological recommendations are applied to estimate the carbon footprint of feedstock CO2 for current CO2 sources in Europe and for future CO2 sources in a scenario for a low carbon economy. For all CO2 sources, the cradle-to-gate footprint of captured CO2 is negative ranging from −0.95 to −0.59 kg CO2 eq. per kg of feedstock CO2 today and from −0.99 to −0.98 kg CO2 eq. in a low carbon economy. The carbon footprints of different CO2 sources differ mainly due to their energy demands. The presented assessment method and the carbon footprints of the CO2 feedstocks CO2 provide the basis for future assessments of carbon capture and utilization processes.
  • Outstanding Reviewers for Energy & Environmental Science in 2019
    Item type: Other Journal Item
    Bell, Alexis; Deretzis, Ioannis; Donat, Felix; et al. (2020)
    Energy & Environmental Science
  • Thermally controlled growth of photoactive FAPbI3 films for highly stable perovskite solar cells
    Item type: Journal Article
    Sánchez, Sandy; Cacovich, Stefania; Vidon, Guillaume; et al. (2022)
    Energy & Environmental Science
    We employ flash infrared annealing to investigate the phase transition of formamidinium lead triiodide (FAPbI3) thin films for their solar cell applications. Measuring the enthalpy changes of the FAPbI3 composition at different heating rates allows us to calculate an activation energy of 1.8 eV for the black perovskite phase transition. We explore different heating regimes for triggering the phase transformation and analyze the evolution of the microstructure with an empirical calculation of the average crystal growth velocity required to form a compact film on the micron and submicron scales. The films were then optoelectronically and structurally correlated by mapping the typical spherulite microstructure of grain domains, indicating a direct relationship between film homogeneity and higher crystal growth rate. Accordingly, we manufactured highly stable black FAPbI3-based perovskite solar cells using the optimal film crystallization processing parameters, with an annealing time of just 640 ms. We achieve a power conversion efficiency (PCE) of 18.5% using the champion device in the absence of any additives, incurring merely a 10% loss in the PCE during maximum power point tracking for 1500 h under full solar intensity exposure of the devices.
  • Molecular design of metal-free D-pi-A substituted sensitizers for dye-sensitized solar cells
    Item type: Journal Article
    Alibabaei, L.; Kim, J.-H.; Wang, M.; et al. (2010)
    Energy & Environmental Science
  • Thermodynamic limits of extractable energy by pressure retarded osmosis
    Item type: Journal Article
    Lin, Shihong; Straub, Anthony P.; Elimelech, Menachem (2014)
    Energy & Environmental Science
    Salinity gradient energy, which is released upon mixing two solutions of different concentrations, is considered to be a promising source of sustainable power. Of the methods available to harvest the salinity gradient energy, pressure retarded osmosis (PRO) has been one of the most widely investigated processes. In this study, we identify the thermodynamic limits of the PRO process by evaluating the obtainable specific energy, or extractable energy per total volume of the mixed solutions. Three distinct operation modes are analyzed: an ideal case for a reversible process, and constant-pressure operations with either co-current or counter-current flow in a membrane module. For module-scale operation, counter-current flow mode is shown to be more efficient than co-current flow mode. Additionally, two distinct thermodynamically limiting operation regimes are identified in counter-current flow mode—the draw limiting regime and the feed limiting regime. We derive analytical expressions to quantify the maximum specific energy extractable and the corresponding optimal feed flow rate fraction and applied pressure for each operation mode. Using the analytical expressions, we determine that maximum extractable energy in constant-pressure PRO with seawater (0.6 M NaCl) as a draw solution and river water (0.015 M NaCl) as a feed solution is 0.192 kW h per cubic meter of mixed solution (75% of the maximum specific Gibbs free energy of mixing). Considering that this is the theoretical upper bound of extractable energy by the PRO process, we discuss further efficiency losses and energy requirements (e.g., pretreatment and pumping) that may render it difficult to extract a sizable net specific energy from a seawater and river water solution pairing. We analyze alternative source waters that provide a higher salinity difference and hence greater extractable specific energy, such as reverse osmosis brine paired with treated wastewater effluent, which allow for a more immediately viable PRO process.
  • Solar-driven gasification of carbonaceous feedstock-a review
    Item type: Journal Article
    Piatkowski, Nicolas; Wieckert, Christian; Weimer, Alan W.; et al. (2011)
    Energy & Environmental Science
  • Topological and network analysis of lithium ion battery components: the importance of pore space connectivity for cell operation
    Item type: Journal Article
    Lagadec, Marie-Francine; Zahn, Raphael; Müller, Simon; et al. (2018)
    Energy & Environmental Science
    The structure of lithium ion battery components, such as electrodes and separators, are commonly characterised in terms of their porosity and tortuosity. The ratio of these values gives the effective transport coefficient of lithium ions in the electrolyte-filled pore spaces, which can be used to determine the ionic resistivity and corresponding voltage losses. Here, we show that these microstructural characteristics are not sufficient. Analysis of tomographic data of commercial separators reveals that different polyolefin separators have similar porosity and through-plane tortuosity, which, in the homogenised picture of lithium ion cell operation, would imply that these different separators exhibit similar performance. However, numerical diffusion simulations indicate that this is not the case. We demonstrate that the extent to which lithium ion concentration gradients are induced or smoothed by the separator structure is linked to pore space connectivity, a parameter that can be determined by topological or network based analysis of separators. These findings enable us to propose how to design separator microstructures that are safer and accommodate fast charge and discharge.
  • Correction: Powering sustainable development within planetary boundaries
    Item type: Other Journal Item
    Algunaibet, Ibrahim M.; Pozo, Carlos; Galán Martín, Ángel; et al. (2019)
    Energy & Environmental Science
    Correction for ‘Powering sustainable development within planetary boundaries’ by Ibrahim M. Algunaibet et al., Energy Environ. Sci., 2019, 12, 1890–1900.
  • The Effect of the Gas-Solid Contacting Pattern in a High-Temperature Thermochemical Energy Storage on the Performance of a Concentrated Solar Power Plant
    Item type: Journal Article
    Ströhle, Stefan; Haselbacher, Andreas; Jovanovic, Zoran R.; et al. (2016)
    Energy & Environmental Science
  • Large-scale hydrogen production via water electrolysis: a techno-economic and environmental assessment
    Item type: Journal Article
    Terlouw, Tom Mike; Bauer, Christian; McKenna, Russell; et al. (2022)
    Energy & Environmental Science
    Low-carbon (green) hydrogen can be generated via water electrolysis using photovoltaic, wind, hydropower, or decarbonized grid electricity. This work quantifies current and future costs as well as environmental burdens of large-scale hydrogen production systems on geographical islands, which exhibit high renewable energy potentials and could act as hydrogen export hubs. Different hydrogen production configurations are examined, considering a daily hydrogen production rate of 10 tonnes, on hydrogen production costs, life cycle greenhouse gas emissions, material utilization, and land transformation. The results demonstrate that electrolytic hydrogen production costs of 3.7 Euro per kg H-2 are within reach today and that a reduction to 2 Euro per kg H-2 in year 2040 is likely, hence approaching cost parity with hydrogen from natural gas reforming even when applying "historical" natural gas prices. The recent surge of natural gas prices shows that cost parity between green and grey hydrogen can already be achieved today. Producing hydrogen via water electrolysis with low costs and low GHG emissions is only possible at very specific locations nowadays. Hybrid configurations using different electricity supply options demonstrate the best economic performance in combination with low environmental burdens. Autonomous hydrogen production systems are especially effective to produce low-carbon hydrogen, although the production of larger sized system components can exhibit significant environmental burdens and investments. Some materials (especially iridium) and the availability of land can be limiting factors when scaling up green hydrogen production with polymer electrolyte membrane (PEM) electrolyzers. This implies that decision-makers should consider aspects beyond costs and GHG emissions when designing large-scale hydrogen production systems to avoid risks coming along with the supply of, for example, scarce materials.
Publications 1 - 10 of 75