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P.W. Gri ffi n et al.
3.3. Improvement potential
3.2. The baseline conditions
The energy inputs to the UED pulp and paper section were based on information from the trade association (David Morgan, CPI, private communication, 2013). This covers all paper mills (51 sites) in the UK (see the Sankey-type energy fl ow diagram presented in Fig. 6), but not the manufacture of “ fi nished paper products ” that use energy in a dif- ferent manner. The information here covers the UK Standard Industrial Classi fi cation (SIC) Code (2007) 17.12 [24]. Their energy use covered around 50% of energy demand at the 3 digit SIC level (i.e., SIC 17.1 - Manufacture of pulp, paper and paperboard) , according to the UK Gov- ernment ’ s former Department of Energy and Climate Change (DECC) [25]. Output from these mills was taken from the information submitted by industrial companies as a requirement of Climate Change Agreements (CCA) and collated by AEA [26]; what is now the consultancy Ricardo Energy & Environment . CCA are voluntary agreements between UK in- dustry and the UK Government ’ s Environment Agency aimed at deli- vering reductions in energy use and GHG emissions. Operators receive a discount on the Climate Change Levy (CCL), e ff ectively a tax on energy delivered to UK non-domestic users, of 90% on electricity bills and 65% on other qualifying input fuels. The CCA for the paper sector is ad- ministered by a wholly-owned subsidiary of the CPI [27]; the Paper Sector Climate Change Management Co. Ltd . Direct GHG emissions come under the remit of the EU Emissions Trading Scheme (EU-ETS). SEC data is reported for the paper sector for some 46 UK paper mills in 2015 [27]. The basis of this information was again con fi rmed by the CPI (David Morgan, CPI, private communication, 2013), although the energy de- mand di ff ered slightly from that reported under the CCA, due to the inclusion of renewable energy sources (that is not reported under CCA). Economic output was taken from the UK Government ’ s Annual Business Survey [28]. Fuel use by CHP plants was based on reported auto-generated electricity (again via David Morgan, CPI, private communication, 2013), and sector heat-to-power (H:P) ratio was calculated from the Digest of United Kingdom Energy Statistics (DUKES) [29]. Similarly, the overall e ffi ciency of CHP was taken from DUKES. Information on ex- ported electricity from CHP was given by the CPI (Morgan, 2013). The fuel used in producing this exported electricity was calculated based on information from DUKES [29]. The Sankey diagram (shown in Fig. 6) depicts the 2010 baseline division of energy inputs (fuels and primary electricity) against comparative outputs (associated with the core paper machines and ancillary processes). The thickness of the ‘ arrows ’ , ‘ links ’ , or ‘ lines ’ is proportional to the quantity of energy. The major role of CHP plants in providing both heat and power is illustrated as an in- termediate node or process. Non-CHP fuel input is assumed to be used in steam systems, based on a report by the UK Carbon Trust (CT) [30]. The SEC of the various processes was then based on information adopted from that study [30], although they were scaled to match the total electricity demand reported by the CPI (Morgan, 2013). Using the same scaling factor for steam use yielded a boiler e ffi ciency of 82%. This is high in comparison to the average for the industrial sector, but not unreasonably so.
3.3.1. The overall context Improvement potentials were initially extracted from the CT study [30], which particularly focuses on UK paper manufacturing rather than on the pulp sub-sector. This mainly covers short-term opportunities, and so was therefore supplemented by information from alternative (international) sources that cover opportunities that involve more major changes to the production process [21,31,32]. There may be some potential for greater use of the wastes from paper production as fuels, for example, and this was considered in the UED in terms of CHP gasi fi cation. However, there was insu ffi cient technical information available to give greater consideration of this opportunity. Pulp pro- duction is comparatively small in the UK. The sector already uses both a substantial amount of recycling and imported pulp. Domestic pulp re- presents just ∼ 6% of the sector input [30], with only two integrated mills in the UK that use mechanical pulping. They could technically convert to chemical pulping, and use the products produced (so-called ‘ black liquor ’ ) to become net zero GHG emitters. Thus, pulp production was not included in the UED. 3.3.2. Fuel switching - towards a bio-economy The Confederation of European Paper Industries (CEPI) [33], a Brus- sels-based non-pro fi t-making organisation representing the European pulp and paper industry, has recommended the further conversion of industrial installations to low or zero carbon energy use, particularly from renewable sources. Bioenergy can be produced from either bio- mass (any purpose-grown material, such as crops, forestry or algae) or biogenic waste (including household, food and commercial waste, agricultural or forestry waste, and sewage sludge). Sustainable bioe- nergy is a renewable resource that is often low carbon, and potentially leads to ‘ negative emissions ’ when coupled to CCS facilities [34]. It has more recently been proposed in a Swedish context [35,36] to integrate a biore fi nery with pulp and paper mills in order to produce high value chemical products [23] alongside conventional outputs. The UK Gov- ernment ’ s UK and Global Bioenergy Resource Model (an updated feed- stock availability model) suggests that there is substantial quantities of indigenous biomass and biogenic waste available even accounting for the application of more stringent sustainability and land use criteria [37]. The total 2030 UK bioenergy resources might be equivalent to some 850 – 1120 PJ; with accessible resources of perhaps 580 – 672 PJ. But many industrial sectors will be competing for this resource along- side, for example, power generation. This is likely to, in any case, drive up biofuel prices. Nevertheless, the UK pulp and paper sector is already substantially invested in the use of biomass feedstock as both a raw material and fuel, although the CPI has advocated further government support for the expansion of UK agricultural land use for woody bio- mass. On-site residuals from paper production (such as ‘ black liquor, waste fi bre, bark and fi nes) are used to generate a biogenic replacement ( syngas ) for natural gas via gasi fi cation. This can be obtained using a variety of feedstocks: solid recovered fuel (SRF), waste wood, and other waste materials. Unfortunately, in their stakeholder engagement with the UK Government, representatives of the paper industry (via the CPI)
Fig. 6. Sankey energy fl ow diagram of the UK Pulp and Paper sector as modelled here; baseline data in 2010. Source: Gri ffi n et al. [9].
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