Environmental sustainability analysis of UK whole wheat bioethanol and CHP systems

7 The UK whole-wheat bioethanol and straw and DDGS based combined heat and power 8 (CHP) generation systems were assessed for environmental sustainability using a range of 9 impact categories or characterisations (IC): cumulative primary fossil energy (CPE), land use, 10 life cycle global warming potential over 100 years (GWP100), acidification potential (AP), 11 eutrophication potential (EP) and abiotic resources use (ARU). The European Union (EU) 12 Renewable Energy Directive’s target of greenhouse gas (GHG) emission saving of 60% in 13 comparison to an equivalent fossil based system by 2020 seems to be very challenging for 14 stand-alone wheat bioethanol system. However, the whole-wheat integrated system, wherein 15 the CHP from the excess straw grown in the same season and from the same land is utilised 16 in the wheat bioethanol plant, can be demonstrated for potential sustainability improvement, 17 achieving 85% emission reduction and 97% CPE saving compared to reference fossil 18 systems. The net bioenergy from this system and from 172370 ha of grade 3 land is 12.1 PJ 19 y –1 providing land to energy yield of 70 GJ ha –1 y –1 . The use of DDGS as an animal feed 20 replacing soy meal incurs environmental emission credit, whilst its use in heat or CHP 21 generation saves CPE. The hot spots in whole-system identified under each impact category 22 are as follows: bioethanol plant and wheat cultivation for CPE (50% and 48%), as well as for 23 ARU (46% and 52%). EP and GWP100 are distributed among wheat cultivation (49% and 24 37%), CHP plant (26% and 30%) and bioethanol plant (25%, and 33%), respectively. 25