Pre-treatment technologies, and their effect on international bioenergy supply chain logistics. Techno-economic evaluation of torrefaction, fast pyrolysis and pelletisation
Introduction
Sustained energy supply is an essential objective to achieve and depends on ensuring secure and reliable energy sources. However, the European Union (EU) import dependency is rising. Unless domestic energy becomes more competitive in the next 20–30 years around 70% of the EU's energy needs are expected to be met by imported products—some from regions threatened by insecurity [1]. On the other hand, fossil fuel consumption causes substantial environmental harm notably, climate change. Energy production and consumption account for 81.5% of the total green house gas (GHG) emissions in the EU-25 [2].
In addressing those threats, the EU is increasingly shifting towards policies favouring use of renewable energy sources. Currently biomass delivers around 4% of the EU's primary energy (Eurostat) and in order to reach the future targets set out by the EU, significant amounts of biomass will be required. The renewable energy target in the EU's overall mix is determined as 20% by 2020, which corresponds to 230–250 MtOE bioenergy depending on various assumptions [3].3 Furthermore as a substitute for transportation fuels, the EU set itself a minimum binding target of 10% biofuel use by 2020. Moreover, bioenergy contributes 22% of the primary energy supply in developing countries, and around 10% of global energy demand [4].
Since some countries have larger land areas used at lower densities compared to others, they may become net suppliers of renewable bioenergy. While biomass production costs in such countries may be relatively low, there will be additional logistic costs, energy uses and material losses [5]. However, several studies have given indications that international trade in biofuel could be economically feasible [6], [7], [8]. These studies, concerning long distance bio-energy transportation, analysed several cases to calculate biomass delivery and final energy production costs. Hamelinck developed a tool with which different bioenergy chains were analysed [5], [6]. This work clarified that densification prior to international transportation of biomass is crucial, as converting biomass into a densified intermediate can save transport and handling costs. In addition, it can improve the efficiency of the final conversion stage. Subsequently, pre-treatment is a key step in the total supply chain. Broadly, feedstock costs contribute around 20–65% of the total delivery cost whereas pre-treatment and transport contribute 20–25% and 25–40%, respectively, depending on the location of the biomass resources [5]. However, recent and potential future improvements of pre-treatment technologies and their subsequent impacts on the overall bioenergy chain have not been addressed in detail.
Currently, the state-of-the-art (SOTA) biomass-to-energy chains are mostly based on pelletisation. However, the pre-treatment technologies such as fast pyrolysis and torrefaction may improve the economics of the overall production chain. However, these technologies are still under development and their economic and technical performances are unclear. There are no normalised data sets available in literature and the available information mainly discusses the technology and the intermediate products, rather than their influence on the performances of the whole production chains. The main objective in this study is therefore to assess which pre-treatment method(s), at what point of the chain, with which conversion technology (ies) would give the optimal power and fuel (syngas) delivery costs for international biomass supply chains.
The study focuses on detailed techno-economic analysis of key pre-treatment technologies, namely torrefaction, pyrolysis and pelletisation and their respective impacts, in terms of costs and energy uses in various chains for biomass production and use.
Section snippets
Methodology and evaluation criteria
A technology review was performed to collect design data of pre-treatment technologies. Mass yields, energy yields and process efficiencies of each technology were evaluated, partly by building simple models to determine energy and mass balances.
The economic evaluation of the technologies was based on component level cost data, which were obtained from literature and personal communication with experts. Since the capacities of the components affect the specific cost of a plant, economies of
Torrefaction
Torrefaction is a thermal pre-treatment technology performed at atmospheric pressure in the absence of oxygen. Temperatures between 200 and 300 °C are used, which produces a solid uniform product with very low moisture content and a high calorific value compared to fresh biomass.
Even though torrefaction is in its infancy, several studies show that torrefaction increases the energy density, hydrophobic nature and grindability properties of biomass [9], [10], [11]. Torrefied biomass typically
Approach and methodology
There are several factors influencing the overall production costs when international bio-energy trade is considered. The location of the pre-treatment process is one important factor since it influences the scale of the subsequent processes which are capital-intensive. Moreover it influences the further transportation and storage options. In this study, five transfer points were considered, namely: local biomass production site, central gathering point, export and import terminals and a final
Discussion and conclusion
The main objective of this study was to identify the optimum biomass-to-energy chains by analysing the pre-treatment technologies (torrefaction, pyrolysis and pelletisation) each of which differ significantly in terms of their impacts on transportation, storage and conversion. The potential and future technical and economic performance of these technologies was analysed. The influences of intermediate products (pre-treated biomass) on transportation cost and energy use were evaluated. The
References (49)
- et al.
Techno-economic analysis of international bio-energy trade chains
Biomass Bioenergy
(2005) Thermal recycling of polymers
J Anal Appl Pyrolysis
(1985)- et al.
Efficiency and economy of wood-fired biomass energy systems in relation to scale regarding heat and power generation using combustion and gasification technologies
Biomass Bioenergy
(2001) - et al.
Biomass and bioenergy supply from Mozambique
Energy for Sustainable Development (Special Issue on Emerging International Bio-energy markets and opportunities for socio-economic development)
(2006) - European Commission. Green Paper, a European strategy for sustainable, competitive and secure energy. COM (2006) 105...
- Wiesenthal T, Fernandez R, Taylor P, Greenleaf J. Energy and environment in the European Union. EEA report. Copenhagen,...
- Mario R, Toro F, Resch G, Faber T, Haas R, Hoogwijk M, et al. Economic analysis of reaching a 20% share of renewable...
- IEA, World Energy Outlook 2006. IEA 2006. See also:...
- et al.
Production of advanced biofuels
Int. Sugar J.
(2006) - Wasser R, Brown A. Foreign wood fuel supply for power generation in the Netherlands, Netherlands agency for energy and...
A new process for torrefied wood manufacturing
Gen Bioenergy
Progress in thermochemical, solid-state refining of biofuels—from research to commercialization
Adv Thermochem Biomass Convers
Pyrolysis of biomass to produce fuels and chemical feedstock
Cited by (490)
An integrated PROMETHEE II-Roadmap model: Application to the recovery of residual agroforestry biomass in Portugal
2024, Journal of Cleaner ProductionHydrothermal treatment of empty fruit bunches for enhanced solid fuel production using palm oil mill effluent as a liquid stream
2024, Bioresource Technology ReportsLife cycle assessment of bioenergy production from wood sawdust
2023, Journal of Cleaner ProductionMachine learning and statistical analysis for biomass torrefaction: A review
2023, Bioresource Technology