Frequently Asked Questions / FAQs
Pyrolysis and Plastic Waste Conversion (PWC) Frequently Asked Questions
COI began a partnership with PDO Technologies in 2021 to create a Portable PWC research and demonstration facility accessible to public evaluation.
1. What is pyrolysis?
Pyrolysis is the thermal decomposition of plastics at elevated temperatures in the absence of oxygen. Another way to say this is the heating of plastics in a closed, oxygen-free environment. It is NOT the burning or incineration of plastics.
2. Is pyrolysis “recycling”?
This depends on how a governing authority defines recycling. Most conversion technology companies differentiate between chemical recycling (end product = fuels) and advanced recycling (end product = plastic). Not all companies make the distinction, however, and both terms can and sometimes are used synonymously.
3. What are the outputs of pyrolysis, including main products and byproducts?
Outputs of the process are on average: 80% liquid fuel, 13% non-condensable gasses, and 7% char. The non-condensable gasses and a portion of the char are reused in the process to lower the energy needs and carbon footprint of the system.
4. How will the remaining char be handled?
If it is not used on-site for energy generation, it can be briquetted and sold into commerce as a low-energy fuel source on par with green coal (ca. 8000 BTU/lb. of energy content). The last, least-ideal alternative is to landfill the material.
5. What type of technology does PDO use and has it been proven to work under real-world operating conditions?
For eight years, PDO has been using low-temperature pyrolysis (510 Celsius) under successful commercial settings in three states (OR, MN, GA) at full scale, fifty tons of plastic per day.
6. What are the expected emissions and how will they be monitored and reported?
Emissions from the process are well-characterized, minor in species concentration(s), and well below regulatory levels. Each state establishes its own emission limits which are tracked using approved testing methodologies required by the permitting authorities at the local and state level pursuant to their reporting requirements. PDO is currently located in Oregon, and the emission factors and limits can be found here. California limits can be found here.
7. Does pyrolysis generate toxic by-products or hazardous waste?
The PDO process generates no hazardous waste per Resource Conservation and Recovery Act (RCRA) definition.
8. What is the energy balance of the process?
Using the common metric Energy Returned on Energy Invested (EROEI), PDO’s machines return 4-7 times the amount of energy used during the conversion process. When compared to traditional fossil fuel extraction, refining, and transportation, PDO’s machines use 96% less energy, 58% less water, and 14% less greenhouse gases.
9. Which type of feedstocks has it been tested on? How much feedstock will be sourced, and from which communities?
PDO’s process has been tested on all “classic” plastics (resin codes 1-7). Resin codes #1 (PETE) and #3 (PVC) are not desirable for use in the technology. Feedstock sourcing will be through partnerships with local companies & municipalities to match the community’s needs.
10. How close will a facility be located to marginalized communities or populated neighborhoods and are there any concerns about causing disproportionate harm to these communities?
PDO’s pyrolysis facilities are classified as “light industrial” and located in areas zoned for that purpose. COI’s goal is to have smaller machines (Portable Plastic Waste Conversion) adjacent to existing recycling facilities to reduce vehicle traffic and transportation impacts. Examples of possible locations are landfills, agricultural complexes, or island communities. Based on the emission profile of current project sites, we have no concerns about disproportionately impacting surrounding communities.
11. How does the fuel quality measure up to regular diesel when combusted?
In terms of combustion characteristics, “pyro diesel” and regular diesel are quite similar. “Pyro diesel” is not considered a diesel fuel alone - it is necessary to blend it with regular diesel. Blending at a ratio of 1:3 “pyro diesel” to certified diesel results in a product that meets the standard specification for diesel fuel.
12. Have the fuel emissions from PDO machines been tested after passing through a diesel engine?
At this point in time, we do not have information on exhaust chemistry from diesel engines running blended fuel using PDO technology. This article has information and additional links to further research evaluating the chemistry of diesel exhaust using pyro-oil. One of our motivations is to increase the understanding of the impacts of pyro-diesel on the environment.
13. Has the fuel from PDO's machines been in use long enough to know how engines are responding over time?
Fuel from PDO technology has been used for twenty years. If PDO’s product is blended with commercial diesel at a ratio such that the resulting fuel always meets the standard diesel oil specification (ASTM D-975), then no adverse impact on the engine is anticipated. Additional analysis will be conducted over the life of the project with the products created.
14. How do different pyrolysis temperatures affect the quality of the resulting fuel?
Different temperatures produce different “profiles” of resulting hydrocarbon molecules exiting the system. PDO’s technology operates at 510C giving it a cleaner profile. For more information on fuels created from 700C and 900C refer to this article and for more information comparing the impacts of different temperatures, click here.
15. Why don’t we just focus on reducing the demand for plastic?
Plastic Waste Conversion addresses the cleanup of plastic waste, which is a different discussion than the reduction of plastic use. Addressing the reduction of demand for virgin plastics is something we highly support and advocate for. There are a number of organizations working on that approach.
This is COI’s proposal until we break away from fossil fuel production. Global plastic waste is projected to ALMOST TRIPLE by 2060. This is our INTERIM solution.
COI began a partnership with PDO Technologies in 2021 to create a Portable PWC research and demonstration facility accessible to public evaluation.
1. What is pyrolysis?
Pyrolysis is the thermal decomposition of plastics at elevated temperatures in the absence of oxygen. Another way to say this is the heating of plastics in a closed, oxygen-free environment. It is NOT the burning or incineration of plastics.
2. Is pyrolysis “recycling”?
This depends on how a governing authority defines recycling. Most conversion technology companies differentiate between chemical recycling (end product = fuels) and advanced recycling (end product = plastic). Not all companies make the distinction, however, and both terms can and sometimes are used synonymously.
3. What are the outputs of pyrolysis, including main products and byproducts?
Outputs of the process are on average: 80% liquid fuel, 13% non-condensable gasses, and 7% char. The non-condensable gasses and a portion of the char are reused in the process to lower the energy needs and carbon footprint of the system.
4. How will the remaining char be handled?
If it is not used on-site for energy generation, it can be briquetted and sold into commerce as a low-energy fuel source on par with green coal (ca. 8000 BTU/lb. of energy content). The last, least-ideal alternative is to landfill the material.
5. What type of technology does PDO use and has it been proven to work under real-world operating conditions?
For eight years, PDO has been using low-temperature pyrolysis (510 Celsius) under successful commercial settings in three states (OR, MN, GA) at full scale, fifty tons of plastic per day.
6. What are the expected emissions and how will they be monitored and reported?
Emissions from the process are well-characterized, minor in species concentration(s), and well below regulatory levels. Each state establishes its own emission limits which are tracked using approved testing methodologies required by the permitting authorities at the local and state level pursuant to their reporting requirements. PDO is currently located in Oregon, and the emission factors and limits can be found here. California limits can be found here.
7. Does pyrolysis generate toxic by-products or hazardous waste?
The PDO process generates no hazardous waste per Resource Conservation and Recovery Act (RCRA) definition.
8. What is the energy balance of the process?
Using the common metric Energy Returned on Energy Invested (EROEI), PDO’s machines return 4-7 times the amount of energy used during the conversion process. When compared to traditional fossil fuel extraction, refining, and transportation, PDO’s machines use 96% less energy, 58% less water, and 14% less greenhouse gases.
9. Which type of feedstocks has it been tested on? How much feedstock will be sourced, and from which communities?
PDO’s process has been tested on all “classic” plastics (resin codes 1-7). Resin codes #1 (PETE) and #3 (PVC) are not desirable for use in the technology. Feedstock sourcing will be through partnerships with local companies & municipalities to match the community’s needs.
10. How close will a facility be located to marginalized communities or populated neighborhoods and are there any concerns about causing disproportionate harm to these communities?
PDO’s pyrolysis facilities are classified as “light industrial” and located in areas zoned for that purpose. COI’s goal is to have smaller machines (Portable Plastic Waste Conversion) adjacent to existing recycling facilities to reduce vehicle traffic and transportation impacts. Examples of possible locations are landfills, agricultural complexes, or island communities. Based on the emission profile of current project sites, we have no concerns about disproportionately impacting surrounding communities.
11. How does the fuel quality measure up to regular diesel when combusted?
In terms of combustion characteristics, “pyro diesel” and regular diesel are quite similar. “Pyro diesel” is not considered a diesel fuel alone - it is necessary to blend it with regular diesel. Blending at a ratio of 1:3 “pyro diesel” to certified diesel results in a product that meets the standard specification for diesel fuel.
12. Have the fuel emissions from PDO machines been tested after passing through a diesel engine?
At this point in time, we do not have information on exhaust chemistry from diesel engines running blended fuel using PDO technology. This article has information and additional links to further research evaluating the chemistry of diesel exhaust using pyro-oil. One of our motivations is to increase the understanding of the impacts of pyro-diesel on the environment.
13. Has the fuel from PDO's machines been in use long enough to know how engines are responding over time?
Fuel from PDO technology has been used for twenty years. If PDO’s product is blended with commercial diesel at a ratio such that the resulting fuel always meets the standard diesel oil specification (ASTM D-975), then no adverse impact on the engine is anticipated. Additional analysis will be conducted over the life of the project with the products created.
14. How do different pyrolysis temperatures affect the quality of the resulting fuel?
Different temperatures produce different “profiles” of resulting hydrocarbon molecules exiting the system. PDO’s technology operates at 510C giving it a cleaner profile. For more information on fuels created from 700C and 900C refer to this article and for more information comparing the impacts of different temperatures, click here.
15. Why don’t we just focus on reducing the demand for plastic?
Plastic Waste Conversion addresses the cleanup of plastic waste, which is a different discussion than the reduction of plastic use. Addressing the reduction of demand for virgin plastics is something we highly support and advocate for. There are a number of organizations working on that approach.
This is COI’s proposal until we break away from fossil fuel production. Global plastic waste is projected to ALMOST TRIPLE by 2060. This is our INTERIM solution.