Economic and European Union Environmental Sustainability Criteria Assessment of Bio-oil Based Biofuel Systems: Refinery Integration Cases

The biofuel mix in transport in the UK must be increased from currently exploited 3.33% to the EU target mix of 10% by 2020. Under the face of this huge challenge, the most viable way forward is to process infrastructure-compatible intermediate, such as bio-oil from fast pyrolysis of lignocellulosic biomass, into biofuels. New facilities may integrate multiple distributed pyrolysis units producing bio-oil from locally available biomass and centralised biofuel production platforms, such as methanol or FischerTropsch liquid synthesis utilising syngas derived from gasification of bio-oil. Alternative to bio-oil gasification is hydrotreating and hydrocracking (upgrading) of bio-oil into stable oil with reduced oxygen content. The stable oil can then be co-processed into targeted transportation fuel mix within refinery in exchange of refinery hydrogen to the upgrader. This paper focuses on the evaluation of economic and environmental sustainability of industrial scale biofuel production systems from bio-oils. An overview of bio-oil gasification based system evaluation is presented, whilst comprehensive process reaction modelling (with 40 overall bio-oil hydrocracking and hydrotreating reaction steps), simulation, integration and value analysis frameworks are illustrated for bio-oil upgrading and refinery co-processing systems. The environmental analysis shows that the former technologies are able to meet the minimum greenhouse gas (GHG) emission reduction target of 60%, to be eligible for the European Union (EU) Directive’s 2020 target of 10% renewable energy in transport, whilst at least 20% renewable energy mix from an upgrader is required for meeting the EU GHG emission reduction target. Increases in the price of biodiesel and hydrogen make co-processing of stable oils from bio-oil upgrader using refinery facilities economically more favourable than final biofuel blending from refineries and create win-win economic scenarios between the bio-oil upgrader and the refinery. The range of the cost of production (COP) of stable oil (328 MW or 0.424 t/t bio-oil), steam (49.5 MW or 0.926 t/t bio-oil) and off-gas or fuel gas (72.3 MW or 0.142 t/t bio-oil) from a bio-oil (LHV of 23.3 MJ/kg) upgrader process is 2 evaluated based on individual product energy values and global warming potential (GWP) impacts. The minimum and the maximum annualised capital charge predicted by the Discounted Cash Flow (DCF) analysis correspond to 25 operating years and 10% IRR; and 10 operating years and 20% IRR; respectively. Based on this DCF strategy and 1200 $/t of hydrogen and 540 $/t of biodiesel market prices, the selling prices of 259.32 $/t, 34.85 $/t and 174.27 $/t of the stable oil, steam and fuel gas, respectively, from the upgrader to the refinery were obtained to create win-win marginal incentive for the upgrader and refinery systems, individually. If stable oil from a bio-oil upgrader can be launched as a product potentially to be used in refinery hydrocracker (at a competitive price of 490 $/t), for the production of renewable diesel, upgrader can be operated independently, such as, purchase hydrogen from vendors at competitive price, with comparative marginal incentives. The bio-oil upgraders, either stand-alone or integrated, were designed to meet desired product specifications, diesel with specific gravity: 0.825 and cetane number: 57 and stable oil with API: 30.1 and cetane number: 28.7, for co-processing through the refinery hydrocracker, respectively.