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The selection of product portfolios, processing routes and the combination of technologies to obtain a sustainable biorefinery design according to economic and environmental criteria represents a challenge to process engineering. The aim of this research is to generate a robust methodology that assists process engineers to conceptually optimise the environmental and economic performances of biorefinery systems. A novel economic value and environmental impact (EVEI) analysis methodology is presented in this paper. The EVEI analysis is a tool that emerges from the combination of the value analysis method for the evaluation of economic potential with environmental footprinting for impact analysis. The methodology has been effectively demonstrated by providing insights into the performance of a bioethanol plant as a case study. The systematisation of the methodology allowed its implementation and integration into a computer-aided process engineering (CAPE) tool in the spreadsheet environment. © 2013 The Institution of Chemical Engineers.

The UK whole-wheat bioethanol and straw and DDGS-based combined heat and power (CHP) generation systems were assessed for environmental sustainability using a range of impact categories or characterisations (IC): cumulative primary fossil energy (CPE), land use, life cycle global warming potential over 100 years (GWP), acidification potential (AP), eutrophication potential (EP) and abiotic resources use (ARU). The European Union (EU) Renewable Energy Directive's target of greenhouse gas (GHG) emission saving of 60% in comparison to an equivalent fossil-based system by 2020 seems to be very challenging for stand-alone wheat bioethanol system. However, the whole-wheat integrated system, wherein the CHP from the excess straw grown in the same season and from the same land is utilised in the wheat bioethanol plant, can be demonstrated for potential sustainability improvement, achieving 85% emission reduction and 97% CPE saving compared to reference fossil systems. The net bioenergy from this system and from 172,370 ha of grade 3 land is 12.1 PJ y providing land to energy yield of 70 GJ ha y. The use of DDGS as an animal feed replacing soy meal incurs environmental emission credit, whilst its use in heat or CHP generation saves CPE. The hot spots in whole system identified under each impact category are as follows: bioethanol plant and wheat cultivation for CPE (50% and 48%), as well as for ARU (46% and 52%). EP and GWP are distributed among wheat cultivation (49% and 37%), CHP plant (26% and 30%) and bioethanol plant (25%, and 33%), respectively. © 2013 Elsevier Ltd.

A biorefinery involving internal stream reuse and recycling (including products and co-products) should result in better biomass resource utilisation, leading to a system with increased efficiency, flexibility, profitability and sustainability. To benefit from those advantages, process integration methodologies need to be applied to understand, analyse and design highly integrated biorefineries. A bioethanol integration approach based on mass pinch analysis is presented in this work for the analysis and design of product exchange networks formed in biorefinery pathways featuring a set of processing units (sources and demands) producing or utilising bioethanol. The method is useful to identify system debottleneck opportunities and alternatives for bioethanol network integration that improve utilisation efficiency in biorefineries with added value co-products. This is demonstrated by a case study using a biorefinery producing bioethanol from wheat with arabinoxylan (AX) co-production using bioethanol for AX precipitation. The final integrated bioethanol network design allowed the reduction of bioethanol product utilisation by 94%, avoiding significant revenue losses. © 2012 Elsevier Ltd.