The role of process intensification in cutting greenhouse gas emissions

Between 1900 and 1955 the average rate of global energy use rose from about 1 TW to 2 TW. Between 1955 and 1999 energy use rose from 2 TW to about 12 TW, and to 2006 a further 16% growth in primary energy use was recorded world-wide. There are recommendations by the UK Royal Commission on Environmental Pollution, subsequently supported by others in the UK, that we need to reduce CO2 emissions by over 50% in order to stabilise their impact on global warming (CO2 being the principal gas believed to be contributing to this phenomenon). One way in which we can address this is by judicious use of process intensification technology.Process intensification may be defined as: “Any engineering development that leads to a substantially smaller, cleaner, safer and more energy-efficient technology.” It is most often characterised by a huge reduction in plant volume – orders of magnitude – but its contribution to reducing greenhouse gas emissions may also be significant.Potential energy savings due to investment in process intensification were studied by several UK organisations in the mid 1990s, to assist the UK Government in formulating a strategy on intensification. It is relevant to the themes of the PRES 07 Conference that process integration features in these analyses. Overall plant intensification in the UK was identified as having a technical potential of 40 PJ/year (about 1 million tonnes of oil equivalent/annum). The total potential energy savings due to investment in process intensification in a range of process unit operations were predicted to be over 74 PJ/year (1 PJ =  1015 J). Projections for The Netherlands suggest that savings of 50–100 PJ/year should be achieved across chemicals and food processing by 2050. Substantial benefits to industry in the USA are highlighted by US Department of Energy studies.This paper relates by discussion and example process intensification to the main themes of the PRES 07 Conference, including process integration. It also identifies the challenges that process intensification is meeting across a range of sectors of industry and commerce, in particular as they relate to greenhouse gas control. By highlighting here the main mechanisms that ‘enhance’ heat and mass transfer in intensified plant, the reader may be stimulated to examine his/her current inefficient processes.