Cherry-stones-based activated carbons as potential adsorbents for CO2/CH4 separation: effect of the activation parameters

This is the accepted version of the following article: Álvarez-Gutiérrez, N., Victoria Gil, M., Rubiera, F. and Pevida, C. (2015), Cherry-stones-based activated carbons as potential adsorbents for CO2/CH4 separation: effect of the activation parameters. Greenhouse Gas Sci Technol, 5: 812–825. doi: 10.1002/ghg.1534, which has been published in final form at http://dx.doi.org/10.1002/ghg.1534A low-cost biomass, cherry stones (CS), was used as a carbon precursor to synthesize two activated carbons to be used for CO2/CH4 separation. Single-step activation with two activating agents, carbon dioxide and steam, was used. The activation conditions that maximize the CO2 adsorption capacity by the adsorbents at 25 ºC and atmospheric pressure were determined by response surface methodology (RSM). The optimum values were 885 ºC and 12% of solid yield when activating with carbon dioxide, but 850 ºC and 15.3% of solid yield when activating with steam. Heating rate did not show a significant effect on the CO2 uptake. CO2 adsorption capacity values up to 11.45 and 10.56 wt.% were achieved under such conditions using carbon dioxide and steam as activating agents, respectively. Carbon dioxide activation promoted the development of microporosity, whereas both micropores and mesopores were developed during steam activation. The CO2/CH4 separation performance at 3 bar of the optimum adsorbents indicated that both cherry-stones-based activated carbons could have great potential as CO2 adsorbents for CO2/CH4 separation. The adsorbent activated with carbon dioxide, CS-CO2, showed a slightly higher adsorption capacity, but the steam-activated sample, CS-H2O, had an enhanced selectivity to separate CO2 from CO2/CH4 binary mixtures.This work was carried out with financial support from the Spanish MINECO (Project ENE2011-23467), co-financed by the European Regional Development Fund (ERDF) and from the Gobierno del Principado de Asturias (PCTI-GRUPIN14-079)Peer reviewe

Fuel cells as combined heat and power systems in commercial buildings: A case study in the food-retail sector

This work investigates the viability of fuel cells (FC) as combined heat and power (CHP) prime movers in commercial buildings with a specific focus on supermarkets. Up-to-date technical data from a FC manufacturing company was obtained and applied to evaluate their viability in an existing food-retail building. A detailed optimisation model for enhancing distributed energy system management described in previous work is expanded upon to optimise the techno-economic performance of FC-CHP systems. The optimisations employ comprehensive techno-economic datasets that reflect current market trends. Outputs highlight the key factors influencing the economics of FC-CHP projects. Furthermore, a comparative analysis against a competing internal combustion engine (ICE) CHP system is performed to understand the relative techno-economic characterisitcs of each system. Results indicate that FCs are becoming financially competitive although ICEs are still a more attractive option. For supermarkets, the payback period for installing a FC system is 4.7–5.9 years vs. 4.0–5.6 years for ICEs when policies are considered. If incentives are removed, FC-CHP systems have paybacks in the range 6–10 years vs. 5–8.5 years for ICE-based systems. A sensitivity analysis under different market and policy scenarios is performed, offering insights into the performance gap fuel cells face before becoming more competitive

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This paper examines where and how claims of procedural injustice, or demands for procedural justice, might arise with respect to carbon capture and storage (CCS), taking a broad view of the CCS research, development and deployment process. It considers the principles that might govern such claims and seeks to identify where responsibility might lie for ensuring justice, or addressing contested claims of injustice. It is suggested that claims of procedural injustice arising from CCS are most likely to arise during implementation, from locally affected populations, raising concerns of inadequate information or consultation; but they may also arise from representatives of other indirectly affected groups, such as those affected by upstream impacts of coal mining, or energy market consequences of CCS policy. It is further suggested that claims are most likely to be directed at public authorities in respect of decisions over policy, strategy or authorisations for individual developments, but there are also routes by which claims may be directed at the corporations involved, especially under human rights provisions. The paper suggests a need for careful consideration of both procedural and, by implication, distributive justice matters in the emerging regulatory and support framework for CCS, with a particular imperative for moving public engagement upstream prior to deployment and indeed even to research programmes, to maximise the scope for legitimate influence on future outcomes