From lignin to marine biofuel - A market potential and GHG assessment of the most suitable conversion routes in Brazil and Scandinavia.

Abstract

The marine transport is a relatively efficient type of transport per amount of volume tranported. However, it does generate large quantities of greenhouse gas (GHG) emissions due to the large volumes that are transported globally. In 2012, the total GHG emissions from shipping amounted 961 million tonne CO₂-eq, which accounted for 2.5% of the global GHG emissions and this is projected to increase with 50 to 250% by 2050 for the business-as-usual scenario. Needless to say, the marine industry could use a way to decrease its GHG emissions. Sustainable second-generation biofuels could offer a solution the problem. Liquid biofuels are suitable to reduce marine transport emissions because it can be blended in different ratios with the fossil fuel, it can be used in any ship, and no, or only small, changes to the engine are needed. Lignin is present in biomass, and is separated from the rest of the plant in paper/pulp mills and lignocellulosic ethanol plants. Every year, around 50-70 Mt of lignin is made available at these sources, most of which is currently combusted to provide process heat. Using the lignin to produce marine biofuel and replace the fossil fuels in ships could make the marine industry more sustainable, while it increases the business-case of the mill or plant. This research assesses the best technologies and the market potential of lignin to marine biofuel conversion. Subsequently, a consequential life-cycle analysis was performed to assess the direct and indirect GHG emissions that are associated with the conversion through this technology for two case studies. The first case study is the conversion of Kraft lignin from a Finnish paper/pulp mill and the second case study assesses the conversion of steam explosion lignin from a Brazilian lignocellulosic ethanol plant. Fast pyrolysis was found to be the most promising technology, mainly because it was the cheapest and already most well-developed option. The quality of the fast pyrolysis oil is quite low, but this can be increased through a subsequent upgrading step using hydrogen. The amount of marine biofuels that could currently potentially be produced from lignin would be roughly 5.2% of the total marine fuel consumption. The GHG assessment shows that a 32% reduction is achieved from using biofuels from Kraft lignin instead of fossil fuels. For the biofuel from SE lignin conversion, 25% reduction is achieved. Roughly between 1.6% and 2.3% of the overall shipping emissions could be mitigated. This percentage is projected to increase to between 1.9% and 2.4% ten years from now. It can be concluded that the use of biofuels from lignin could be effective in mitigating emissions, but even if the GHG emission savings are increased and the technical barriers are overcome, the quantity of biofuels is not sufficient to realise a large reduction in the GHG emissions of the shipping industry. Therefore, marine biofuels from lignin could be important to reduce the GHG emissions from the shipping industry, but additional measures should also be researched and implemented. The model and assumptions used for this research should be validated by future research.