The target of VTT research is to accomplish this by knowing the properties of wide range of recovered heterogenous materials, creating and integrating technologies to utilise these material flows to new solutions and sustainable products to the markets, creating new value chains for Finnish industry, expanding VTT’s expertice in finding solutions for challenging approaches, and expanding the co-operation of VTT with industrial partners.
In search for alternative fuels
Today, regulations and norms guide waste from landfilling to material and secondly to energy use. In Finland, ban for landfilling organic waste came in to force in January 2016. The long-term objective of societies is to replace fossil and first generation renewable fuels and solvents with liquids and gases produced from low-value organic by-products and wastes, such as biomass residues from agriculture and forestry, energy crops or municipal, commercial and industrial waste streams. Together with
industrial partners, VTT has started such work within the Tekes ARVI SHOK in 2015, which among other issues focuses on research of mechanical material and thermochemical recycling processes, and concepts utilising plastic waste/recycled plastic/rubber.
The concern about global warming, stringent emissions legislation, gradual reduction of crude oil reserves, volatility of conventional fuel prices, and increasing global demand for transport energy have led to the search for alternative fuels for internal combustion (IC) engines and gas turbines. Renewable fuels have the potential to become the sustainable energy sources for IC engines and gas
turbines. The goal is supported by the European Union which has made a commitment to increase the use of renewable energy and utilise wastes. In the 2020 climate-energy packages, the EU is committed to reduce greenhouse gas emissions by 20 %, with respect to 1990, and to achieve a share of renewable energy sources of 20 %.
It is obvious that the costs of biofuels must be significantly
reduced. Various waste and secondary materials can be used as feedstocks for production of materials, chemicals, or liquids in order to reduce costs. This aim is reinforced by the waste Framework Directive (2008/98/EC), which addresses that secondary materials and waste should be used preferably several times as a product before its end-of-life in energy use or landfilling.
In Finland, industry, Tekes and VTT have invested together to bio-oil development during the past years. As a result of the consistent work 1,2 an integrated demonstration plant producing bio fuel oil is currently operational in Joensuu, Finland. The fast pyrolysis consortium has reached demonstration of bio fuel oil production in less than 6 years (Figure 1). Finnish industry and VTT have a common goal to reach international markets and gain increased payback from bio-oil. Currently bio-oil is used in replacing fossil boiler fuels. Next step could be widening the feedstock base to plastics.
Plastic-rich waste feedstocks
for thermal conversion
Plastic waste forms complex and heterogeneous stream that is currently poorly exploited. In 2014, around 26 million tonnes of post-consumer plastic waste was generated in Europe, of which less than one third was recycled. This is due to the fact that plastics recycling is almost entirely focused on mechanical recycling that is suitable only for homogenous and contaminant-free plastic waste, which most of the plastic wastes are not. For example, end-of-life vehicles (ELVs), wastes from construction and demolition (C&D), and waste electrical and electronic equipment (WEEE) all contain large share of plastics that cannot be recycled via mechanical routes. Also plastic packaging wastes often contain composite materials and laminate structures whose mechanical recycling is challenging.
However, thermal conversion could be an answer to this dilemma as it poses a necessary contribution to converting plastic-rich complex waste feedstocks into secondary resources in those many cases when direct reuse or mechanical recycling are not viable. Thermal conversion is applicable to more heterogenous feedstocks and the material does not need to be as clean as in mechanical recycling of plastic wastes, as the process can tolerate many forms of contamination and is able to remove impurities.
Liquid fuels from plastic-containing wastes
Under ISO 15270, conversion technologies, such as pyrolysis and depolymerization are recognized as forms of feedstock recycling and upscaling technologies when the products are used for the production of fuels or raw chemicals. Fast pyrolysis technology for wood has already been demonstrated industrially, while pyrolysis of plastics into liquid fuels is being developed. Co-pyrolysis of biomass and plastics is a promising technical alternative to enhance the flexibility of the fast pyrolysis process and improve fuel quality of pyrolysis oils from biomass waste. One of the principal advantages of co-pyrolysis is that it may be applied to existing pyrolysis biomass plants.
Several plastic to liquids (PTL) pyrolysis demonstration plants exist in Europe and elsewhere. 16 commercial size PTL systems were in operation in India, 3 in USA,
3 in Europe, and 1 in Japan in 2015. Typical PTL system capacity is 10–60 TPD (tonnes per day). Main technology suppliers are Cynar in Europe, Agilyx in USA, Toshiba Corporation in Japan, and Pyrocrat Systems LLP in India.
Present PTL demonstration plants apply various permitting systems:
– Pre-processing off-site, which may facilitate permitting as a manufacturing facility rather than a waste processing facility
– The supplier may pursue a solid waste permit and undertake pre-processing onsite, thereby increasing access to feedstock and decreasing material acquisition costs.
– Revising regulations to increase material storage limits on-site to allow for pre-emptive feedstock acquisition prior to system startup.
– When a PTF (plastics to fuel) system is co-located with a MRF (Materials Recovery Facility), it can be covered under an existing solid waste management or recycling permit.
Several demonstration PTL rotary kilns plants (typically 10–20 TPD) for waste tyres exist. Tyre pyrolysis oil is chemically complex containing aliphatic, aromatic, hetero-atom and polar fractions, similar to a gas oil or light fuel oil. Variation in feed quality, high heavy metal, and contents, and low flash point are the most critical properties considering the fuel application.
The latest generation PTL pyrolysis technologies are designed to accept a wide variety of resin types, can accommodate many forms of contamination and require little pre-treatment before being fed into the system. However, to ensure sufficient quality of the product, at least some pre-treatment of the feedstock material seems obligatory. Mechanical and sensor based smart pre-treatment techniques are currently seen as most promising for processing complex waste streams. Mechanical pre-treatment refers to operations that aim to treat waste via mechanical processes, such as chrushing/shredding, washing, separating, drying, homogenization, re-granulating and compounding. Mechanical processes are usually a combination of sorting, comminution and classifying steps which are implemented in series.
The pre-treatment methods required prior thermal conversion are heavily dependent on the feedstock quality and composition. The characteristics of the materials that are fed into thermal conversion have a strong influence on the quality and value of the end product, and should be investigated. Also the complex nature of the feedstocks may set specific requirements for the applicability of the different pre-treatment methods. In addition, the conversion technology may also impose its own limitations for product of the pre-treatment. Thus, the treatment structure and equipment varies from case to case.
System solution for commercial and industrial waste
One concept which VTT has developed with industry is The Urban Mill Concept which reorganizes and creates synergies between management of municipal waste streams, production of recycled paper and energy production from waste streams. The remaining waste materials after separation of fibers for paper production is called Urban Mill reject material. In an earlier case study, pyrolysis process was proved to be a technically and economically promising alternative for converting these reject materials, especially if energy content of the Urban Mill reject material exceeds the local demand for heat. The combined demand of steam in pulping and paper making process and demand of hot water for district heating was too small to allow full utilisation of the reject material in combined heat and power (CHP) production. As an alternative for uneconomic production of condensing electrical power, reject materials may be pyrolysed into a high-value, transportable fuel oil at anenergy yield of 50 % to 70 %. Urban Mill Concepts would offer substantial economic, environmental and social advantages. The concept’s economic competitiveness arises mainly from integration benefits such as cost savings, improved logistics, more uniform and lower cost feedstock due to efficient materials recycling.
Thermal conversion could
be an answer in future
Today, regulations and norms guide waste from landfilling to material and secondly to energy use. In Finland, ban for landfilling organic waste came in to force in January 2016. Organic and other plastic-containig waste forms complex and heterogeneous stream that is currently poorly exploited. In 2014, around 26 million tonnes of post-consumer plastic waste was generated in Europe, of which less than one third was recycled. This is due to the fact that plastics recycling is almost entirely focused on mechanical recycling that is suitable only for homogenous and contaminant-free plastic waste, which most of the plastic wastes are not.
The long-term objective of societies is to replace fossil and first generation renewable fuels and solvents with liquids and gases produced from low-value organic by-products and wastes, such as biomass residues from agriculture and forestry, energy crops or municipal and industrial waste streams. Thermal conversion could be an answer to this dilemma as it poses a necessary contribution to converting organic and plastic-rich complex waste feedstocks into secondary resources in those many cases when direct reuse or mechanical recycling are not viable. Thermal conversion is applicable to more heterogenous feedstocks and the material does not need to be as clean as in mechanical recycling of plastic wastes, as the process can tolerate many forms of contamination and is able to remove impurities.
Anja Oasmaa, Principal Scientist, Lic.Sc.(Tech.), PhD. Anja Oasmaa has over 25 years R&D experience on liquid biofuels at VTT. The work has covered liquid fuel production from various feedstocks by different processes, and at various scales. Oasmaa has developed and validated analytical methods for characterisation and determination of fuel oil quality of fast pyrolysis oils. Oasmaa has been the Finnish representative in IEA Bioenergy Pyrolysis Task and with the group provided data for ASTM boiler fuel standardisation, initiated CEN standardisation in Europe, and provided data for REACH registration. Oasmaa has 5 patents, over 100 scientific publications (H-index 25).
Jutta Laine-Ylijoki, Senior Scientist, M.Sc. (Tech), has over 20 years professional experience in waste processing and management, recycling and water treatment technology development and diverse environmental impact and sustainability assessments. Laine-Ylijoki has long experience in waste and mine waste characterization and treatment, (bio)leaching, risk evaluations and life cycle analysis of both wastes and products. Research has covered legislative and waste-to-energy/product issues and development of quality management and productisation systems for waste recycling and utilisation. She is a key contributor to several ground-breaking research topics (e.g. Eco-Mining; 1st prize in Aalto-VTT Innovation Cup 2009 and Honorary mention in EARTO Innovation Prize Competition 2010).
Henna Punkkinen, M.Sc. works as a Research Scientist in VTT’s Material processing and geotechnology team. She completed her M.Sc. degree at the University of Helsinki, Department of Geology, in 2010, and has been working at VTT since 2008. Her
research has focused on waste utilization and management, including e.g. recycling and recovery of waste
materials and technology evaluations. The research topics have included e.g. waste collection and treatment options, studies of plastics waste recycling and environmental aspects related to mining, as well as issues related to material’s scarcity.
Solantausta, Yrjö, Oasmaa, Anja, Sipilä, Kai, Lindfors, Christian, Lehto, J., Autio, J., Jokela, P., Alin, J., Heiskanen, J.. 2012. Bio-oil production from biomass: Steps toward demonstration: ACS. Energy & Fuels, Vol. 26, Nr. 1, Pp. 233-240
Lehto, Jani, Solantausta, Yrjö, Oasmaa, Anja, Autio, J., Heiskanen, J.. 2013. Demonstration of an integrated co-production of renewable heating bio-oil in CHP-boiler. Renewable Energy World Europe 2013, 4 - 6 June 2013, Vienna, Austria. Conference proceedings
Plastics Europe 2015. Plastics - the Facts 2015. http://www.plasticseurope.org/Document/plastics---the-facts-2015.aspx
2015 PLASTICS-TO-FUEL PROJECT DEVELOPER’S GUIDE, Prepared For: The American Chemistry Council, Prepared By: OCEAN RECOVERY ALLIANCE
VTT Symposium 222. http://www.vtt.fi/inf/pdf/symposiums/2002/s222.pdf