Impact of fly ash content and fly ash transportation distance on embodied greenhouse gas emissions and water consumption in concrete

Background, aim and scope Fly ash, a by-product of coal-fired power stations, is substituted for Portland cement to improve the properties of concrete and reduce the embodied greenhouse gas (GHG) emissions. Much of the world's fly ash is currently disposed of as a waste product. While replacing some Portland cement with fly ash can reduce production costs and the embodied emissions of concrete, the relationship between fly ash content and embodied GHG emissions in concrete has not been quantified. The impact of fly ash content on embodied water is also unknown. Furthermore, it is not known whether a global trade in fly ash for use in concrete is feasible from a carbon balance perspective, or if transport over long distances would eliminate any CO(2) savings. This paper aims to quantify GHG emissions and water embodied in concrete (f'(c)= 32 MPa) as a function of fly ash content and to determine the critical fly ash transportation distance, beyond which use of fly ash in concrete increases embodied GHG emissions

Cellulase recycling in biorefineriesis : is it possible?

On a near future, bio-based economy will assume a key role in our lives. Lignocellulosic materials (e.g., agroforestry residues, industrial/solid wastes) represent a cheaper and environmentally friendly option to fossil fuels. Indeed, following suitable processing, they can be metabolized by different microorganisms to produce a wide range of compounds currently obtained by chemical synthesis. However, due to the recalcitrant nature of these materials, they cannot be directly used by microorganisms, the conversion of polysaccharides into simpler sugars being thus required. This conversion, which is usually undertaken enzymatically, represents a significant part on the final cost of the process. This fact has driven intense efforts on the reduction of the enzyme cost following different strategies. Here, we describe the fundamentals of the enzyme recycling technology, more specifically, cellulase recycling. We focus on the main strategies available for the recovery of both the liquid- and solid-bound enzyme fractions and discuss the relevant operational parameters (e.g., composition, temperature, additives, and pH). Although the efforts from the industry and enzyme suppliers are primarily oriented toward the development of enzyme cocktails able to quickly and effectively process biomass, it seems clear by now that enzyme recycling is technically possible.Financial support from FEDER and Fundação para a Ciência e a Tecnologia (FCT): GlycoCBMs Project PTDC/AGR-FOR/3090/2012–FCOMP-01-0124- FEDER-027948 and Strategic Project PEst-OE/EQB/LA0023/2013, Project BBioInd-Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028 Cofunded by the Programa Operacional Regional do Norte (ON.2–O Novo Norte), QREN, FEDER and the PhD grant to DG (SFRH/BD/88623/ 2012) and ACR (SFRH/BD/89547/2012)

An assessment of the diversity in scenario-based tsunami forecasts for the Indian Ocean

This work examines the extent to which tsunami forecasts from different numerical forecast systems might be expected to differ under real-time conditions. This is done through comparing tsunami amplitudes from a number of existing tsunami scenario databases for eight different hypothetical tsunami events within the Indian Ocean. Forecasts of maximum tsunami amplitude are examined at 10 output points distributed throughout the Indian Ocean at a range of depths. The results show that there is considerable variability in the forecasts and on average, the standard deviation of the maximum amplitudes is approximately 62 of the mean value. It is also shown that a significant portion of this diversity can be attributed to the different lengths of the scenario time series. These results have implications for the interoperability of Regional Tsunami Service Providers in the Indian Ocean. © 2013 Elsevier Ltd