ERTC 2024
Biomass and plastic waste gasification: Enabling the energy transition and circular economy
Harold Boerrigter and Sven Felske Shell Catalysts & Technologies
As the demand for lower-carbon and more circular products intensifies, more and more refiners and chemical manufactur- ers are evaluating the potential benefits of revamping existing gasification units to help enable the energy transition and the plastic circular economy. Gasification of hydrocarbon feedstocks to produce syngas and other products is an established process. Now, through the development of pre-conversion technolo- gies – which can process more challeng- ing plastic, biomass, and unsorted waste streams – gasification could prove a piv- otal technology for the production of lower- carbon, synthetic biofuels, in addition to helping to significantly increase plastic recycling rates. Importantly, reconfiguring existing gasi- fication units can be simple and cost-effec- tive. This can help unlock advantaged feeds that cannot be processed by other recy- cling methods, such as mechanical recy- cling and chemical recycling with pyrolysis. The case for change There is a growing imperative to switch from fossil-based transport fuels, which account for about 20% of global CO₂ emissions, to lower-carbon, bio-based, and synthetic fuels. For example, the EU’s ReFuelEU aviation initiative mandates a progressive increase in the use of sustain- able aviation fuels (SAF) and synthetic avia- tion fuels. By 2035, aviation fuel supplied at EU airports must contain at least 20% SAF – a 900% increase compared with 2025 requirements. At the same time, the world is generat- ing about 2.1 billion tonnes of solid waste every year, between 5 and 12% of which is plastic. With only 9% of plastic waste recycled each year, legislation and initia- tives to tackle plastic waste and increase circularity are becoming central to efforts. For example, the EU has introduced a ban on member states exporting hazardous or hard-to-recycle plastic to non-Organ- isation for Economic Co-operation and Development (OECD) countries. It set stringent waste-reduction targets, which include increasing its plastic recycling rate to 55% by 2030. gasification opportunity Gasification is an established process that can convert a wide range of mixed munic- ipal, biomass, and unsorted plastic waste and residues into an intermediate product known as syngas. This versatile feedstock can be used instead of virgin hydrocarbons to produce fuels, electricity, chemicals, and plastic ( Figure 1 ). Adapting existing gasification units to process waste streams is relatively sim- ple and inexpensive. It provides companies with two key opportunities: • Biofuels: Companies can leverage sig- nificant volumes of low-value sustainable
did you know? A key part of the gasification process is pre-conversion, starting biomass and waste into a suitable feedstock for the gasification unit which involves converting the
Natural gas and o -gases, RNG
Feedstock (after pre-conversion)
Aviation and transportation fuels
Fischer-Tropsch
Clean syngas (CO + H )
H , ammonia, methanol, oxo-alcohols
Re neries’ liquid residue and biomass pyrolysis oil
Chemicals
Gasi cation and gas treating
Renewable natural gas
Methanation
Liqui ed waste plastic
Steam and electricity
Power generation
Oxygen and steam
Biomass
Municipal waste 60–70% biomass
Carbon capture utilisation and storage (CCUS)
CO
Greenhouses, industry and storage
Sulphur
RNG = renewable natural gas
Figure 1 Gasification can produce low carbon intensity syngas for conversion into a wide range of lower-carbon and more circular products
Woody biomass
Biomass, agricultural residues, waste
Sorted plastic waste
Fast pyrolysis
Torrefaction
Liquefaction
Liquids (feeding system)
Solids (feeding system)
Liquids (feeding system)
attractive for greenfield projects compared with the fast pyrolysis route.
Gasi cation
Low-carbon-intensity, circular syngas
Plastic liquefaction for bulk plastic waste Today, as much as 85% of plastic waste is sent to landfill, incinerated, or left unman- aged, largely because current methods, including mechanical recycling and chemical recycling by pyrolysis, require well-sorted, high-purity plastic waste streams, which are costly and resource-intensive to create. Plastic liquefaction, however, can take rejected bulk, unsorted plastic waste and convert it into gasification feedstock to pro- duce syngas. As such, it is a complemen- tary recycling method that can contribute significantly to closing the plastic recycling loop and the production of circular plastics. The plastic pre-conversion process uses a novel plastic liquefaction unit developed as part of a strategic collaboration with Hyundai. This unit can be installed upstream of an existing gasification unit. While the gasifier needs to be adjusted for the new feedstock used, downstream units (syngas treatment, methanol synthesis and meth- anol-to-olefins units) require no modifica- tion. As such, plastic gasification can be deployed quickly and at a relatively low cost. Technology ready As demand for lower-carbon and more sustainable products grows, gasification of pre-converted biomass and waste can offer a quick-to-deploy and cost-effective solution that can leverage existing gasifi- cation units with only minor adaptions and novel pre-conversion technologies. Crucially, gasification has the poten- tial to unlock advantaged feeds, such as low-value biomass residues and unsorted plastic waste, and convert them into high- value, bio-based and circular fuels, chemi- cals, and plastics with attractive margins.
Figure 2 Pre-conversion relies on one of three technologies, depending on the type of waste used
biomass residues, such as those from indus- trial processes, to produce low-carbon, bio- based fuels with significant margins. • Circular plastic: Companies can use the growing supply of low-value waste plas- tic to produce high-value circular plastic products and achieve potentially higher margins. Pre-conversion for gasification A key part of the gasification process is pre-conversion, which involves convert- ing the starting biomass and waste into a suitable feedstock for the gasification unit. Pre-conversion involves one of three key processes, depending on the biomass or waste stream used ( Figure 2 ):
Biomass Gasification Process – yields pyrolysis oil suitable for gasification in, for example, a Shell liquids gasifier with waste heat recovery. In fact, fast pyrolysis can be deployed in existing liquid/residue gasifi- ers with only minor adaptions to the feed system. Moreover, because fast pyrolysis is simple and cost-effective to deploy, it can contribute to a faster reduction in car- bon intensity and production of low-carbon products. Torrefaction for solid biomass, residue, and unsorted waste materials Torrefaction, suitable for a wide range of biomass and unsorted waste streams, pro- duces a product, with similar properties to lignite, which can be used in commercially proven lignite gasification units. Lower unit technical costs make torrefaction more
Fast pyrolysis for woody biomass Fast pyrolysis – part of the Integrated Shell
Contacts: Harold.Boerrigter@shell.com Sven.Felske@shell.com
Today, as much as 85% of plastic waste is sent to landfill, incinerated, or left unmanaged
13
Powered by FlippingBook