Slow Pyrolysis

The Pacific Pyrolysis slow pyrolysis technology is truly carbon negative (reduces atmospheric CO2) by using waste biomass such as animal manures and greenwaste to produce renewable energy and biochar, a product that contains high quantities of very stable carbon. The renewable energy produced can displace fossil fuels, while biochar can sequester carbon beneficially over the long term in soil, which is a natural, low risk sink. The Pacific Pyrolysis technology platform is based on slow pyrolysis, which is the thermo‐chemical decomposition of organic material (biomass) at elevated temperatures in the absence of oxygen.  The diagram below shows the technology process in simplified form:

Pacific Pyrolysis Slow Pyrolysis Simplified Process Flow Diagram

Technology Diagram

The technology platform has been engineered to heat organic matter in a vessel, which is designed to provide an oxygen free environment whilst allowing continuous processing. The organics held under these conditions do not have the oxygen required to combust, instead they undergo pyrolysis reactions. The decomposition of the organics at temperature leads to the liberation of a combustible gas (syngas), a process known as de‐volatilisation. The process also yields a solid product, called biochar. The biochar is a concentrated carbon product which is chemically very stable due to its aromatic structure.

The technology is capable of processing feed streams with a large range of particle size distributions (from dust up to 40mm) and moisture contents (from bone dry to 70%). Contaminants in the feedstock, such as metals and glass, which often prevent the beneficial use of the organic materials, if within size specification can pass through the process and are comparatively easy to separate from the friable biochar product. Organics feedstocks are often contaminated with film plastics, which make them difficult to market. The pyrolysis process is well suited to processing organics with these contaminants, as they have high energy densities which are converted to syngas, offering a true alternative to landfill for these materials  

A wide range of feedstocks have been demonstrated in the Pacific Pyrolysis trial facilities, many of which present a waste management issue looking for solutions:

• municipal green waste;
• wood waste (including processing
  plants, mills, forest residue, packaging
  timber, construction and demolition);
• woody weeds;
• bagasse (sugar cane trash);
• paper sludge;
• biosolids (waste water sludges);
• animal manures and bedding;
• nut shells and husks;
• crop residue;
• distillers grain; and
• industrial organic waste.

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Key Design Features

Key design features of the Pacific Pyrolysis technology include:

• Syngas clean‐up with utilisation of all volatiles for energy
  generation (no condensation of biooils).
• Continuous operation, reducing thermal stresses on plant.
• Biochar conditioner for consistent commercial quality biochar
  production and quality control.
• Low capital cost, due to low temperature and pressure profiles, and fixed kiln design.
• Majority of plant equipment consists of mature ‘commodity’ engineering technology.
• Scale suited to distributed energy model, limiting transport requirements
  for biomass and producing quantities of power which are significant
  yet easily accommodated by existing users and networks.
• World class emissions control standards.
• World class work place health and safety standards.
• Waste heat recovery for drying ensures optimum efficiency.
• Robust materials handling, suitable for a diverse range of feedstocks.
• Integrated control system with buffering of material flows for improved operability.
• Fully automated control system allowing “Best Practice” optimisation of
  process and reduction of operating cost escalation risk through lower labour inputs.
• Modular design for ease of transport, installation, commissioning and relocation.
• Plant configured to ensure ease of maintenance.
• Flare for the complete combustion of excess syngas to ensure
  minimised greenhouse gas balance and emissions.

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Carbon Offsets Generated

There are several avenues in which the technology can mitigate greenhouse gas evolution. 

These include:

• Renewable energy generation (Displacing fossil fuel);
• Bio‐sequestration (Stabilising biochar carbon into terrestrial sinks);
• Reduced agriculture emissions (from reduced nitrous oxide from soil,
  fuel use, fertiliser use, and water use efficiency);
• Decreased emissions from waste biomass (including avoided
  methane generation from landfills and compost production);
• Increased agricultural productivity (increased biomass yields
  create a positive feedback loop).

The pyrolysis process is unique in that it can achieve carbon negative renewable energy generation. This is due to the fact that a portion of the GHG forming carbon in the fuel source is not released through the energy cycle, rather it is stabilised as the biochar product. If organics are not used as fuel they decompose relatively quickly, releasing the carbon naturally back to the atmosphere. Production of biochar however removes this material from the short‐term carbon cycle, into the long‐term carbon cycle. The co‐production of biochar along with renewable energy results in a significant net removal of GHGs from the atmosphere.

It should be noted that not all biochar technologies are carbon negative due to carbon leakage and poor combustion systems. It is essential that understanding, monitoring and auditing of the system is carried out to verify carbon offsets generated. The Pacific Pyrolysis system addresses excessively long distance transport distances through its distributed modular approach and complete capture and utilisation of syngas.

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Technology Development Life Cycle

Over more than 10 years, BEST Energies Australia and Pacific Pyrolysis have made an ongoing investment into slow pyrolysis process development, engineering, and control systems in an effort to achieve the multiple outcomes of biomass waste management, renewable energy and Agrichar™ soil amendment production.  During this time a series of prototypes have been developed and operated starting with small batch units and culminating in integrated large continuous flow systems.  The following schematic outlines the nine stage technology development life cycle for the Pacific Pyrolysis slow pyrolysis technology.

Pacific Pyrolysis Slow Pyrolysis Development Life Cycle

Technology Development Life Cycle

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Demonstration Facility

Pacific Pyrolysis Demonstration Facility
Pacific Pyrolysis Slow Pyrolysis Demonstration Facility

Pacific Pyrolysis has an operational continuous flow slow pyrolysis pilot demonstration facility, named PyroChar 300, at the Somersby Advanced Engineering Facility north of Sydney.  The pilot demonstration facility has a capacity of approximately 300kg/hr (dry basis) of biomass material and is capable of powering a 200 kW electrical generator which is integrated on site. The PyroChar 300 facility has been used to produce quantities of Agrichar™ soil amendment for research programs since 2006 and has a fully documented set of run logs dating back to this time.

The demonstration facility fulfils a number of key roles including:

  • • Providing data required for the development of detailed process flow
  •   diagrams (mass and energy balances) of the technology and verification
  •   of unit operation modelling for scale‐up de‐risking;

• Production of Agrichar™ biochar product samples for use in market development;

• Gas analysis of syngas for energy use specification; and

• Materials handling and operations experience with the different feedstocks.

The data acquired from the demonstration facility has assisted the team in facilitating the development of flexible economic modelling, which is utilised to optimise the business case in project development work. Pacific Pyrolysis is in a unique position with sophisticated mass and energy balance calculations for a variety of feedstocks that input into the economic modelling for projects to which the licensed technology can be applied.

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Commercial Designs

Pacific Pyrolysis has process system and mechanical designs for 48 (2 tph) and 96 (4 tph) dry tonne‐per‐day commercial units (PyroChar 2000 and PyroChar 4000 respectively). Three dimensional modelling of the 4tph unit design can be seen below.

Pacific Pyrolysis PyroChar4000
Pacific Pyrolysis Commercial 4 tph Pyrolysis Design

These designs are scale ups of the known elements which have been successfully integrated and operated at the 300 dry kg per hour pilot plant runningat the Somersby Advanced Engineering Facility north of Sydney.  Mass and energy balances along with modular mechanical design of the 48 and 96 dry tonne‐per‐day units have been completed by Pacific Pyrolysis engineers based on trials from the demonstration unit. These modular units can be designed with an engine component (as is the case with the demonstration plant) for electricity production or to interface with thermal processes such as steam boilers.

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