Utilization of Heat and CO2 from Waste Incineration by Factories to Implement LCCN

FUJII Minoru, Head, System Innovation Section, Social Systems Division
2024.7.30

Preparations are underway for the social implementation of a new system, Life Cycle Carbon Neutral (LCCN), which aims to achieve carbon neutrality throughout the lifecycle of materials from production to disposal. In this system, we use heat produced by waste incineration as energy in chemical plants, paper mills, and other industrial facilities, and use CO2 released by incineration as a raw material for producing plastics.

Why is it necessary now to implement the LCCN system, including utilizing heat and CO2 produced by waste incineration, in addition to recycling? We asked Dr. Fujii, who is working to accelerate the social implementation of LCCN systems domestically and internationally.

FUJII Minoru
Dr. of Eng. from the Graduate School of Engineering, the University of Tokyo(UTokyo).
After working as an assistant professor at UTokyo, he joined the National Institute for Environmental Studies as a researcher in 2003 and was promoted to his current position in 2017. He is also a visiting professor at the Nagoya University Graduate School of Environmental Studies and UTokyo Graduate School of Frontier Sciences, and is the Chair of the Council for Advance Resource Circulation and Digitalization.

1. Carbon neutrality for plastic from production to waste disposal

What is Life Cycle Carbon Neutral (LCCN)?

First, let me explain the background for LCCN. While electrification based on renewable energy is an assumption for decarbonizing society that has attracted great attention, it has also become important to consider how to achieve carbon neutral material lifecycles from production to waste disposal.

Currently, while there is a system to recycle used PET bottles into new PET bottles, nearly half of source-separated plastic packaging other than PET bottles is not recycled as plastic. Most plastic packaging contaminated by food or paper attached cannot be recycled and is incinerated. To achieve a carbon neutral society, these materials must be recycled back into plastic without emitting CO2.

In the LCCN system, unrecyclable waste is incinerated to provide the energy required to produce plastics and other materials. The CO2 emitted by incineration is captured to recirculate the carbon as a raw material for producing plastics, thereby achieving carbon neutrality throughout the entire life cycle of plastics from production to disposal. Thus, the system has been named Life Cycle Carbon Neutral.


How is the heat generated from incinerating waste currently being used? Also, what does it mean to use CO2 as a raw material for plastics?

Most of the heat produced by incineration is used for power generation. However, the energy efficiency of waste to electricity is not very high. In LCCN systems, difficult-to-recycle waste (miscellaneous combustible material such as mixed plastics, paper, rubber, and leather) is incinerated, with the steam generated being used to supply heat with high thermal efficiency . Chemical plants that manufacture plastics use large amounts of steam. However, as it is difficult to transport steam over long distances, we are considering the construction of large-scale incinerators near petrochemical complexes to use the generated heat.

The CO2 released by incineration is captured from the stack and reacted with “green hydrogen” produced using renewable energy to produce methanol and ethanol, which can then be used as feedstocks to produce plastics.

Figure 1. Schematic of a carbon neutral circular plastics economy. The LCCN plant supplies the chemical plant with CO2 as a raw material to produce plastics and steam to run the plant.

2. Waste to steam supply has about twice the energy efficiency of waste to electricity

I have thought the heat from waste incinerators was being used to heat swimming pools.

To provide benefits to the local community, many local governments have installed heated swimming pools next to their incinerators and allow residents to use them at low cost. Although using the heat from incinerators to heat pools is okay, there may be better uses. As the supply of renewable energy increases, it might be a good idea to use surplus electricity generated by solar panels during the day to supply the hot water instead.

For hot water supply, a heat pump water heater (for example, Eco Cute) efficiently extracts heat from the outside air. Heat pumps extract heat from a temperature difference, so they are inefficient for supplying industrial steam at temperatures at or above 100 °C. However, they are good at producing hot water.

Is waste to electricity also a wasteful use of energy?

It is not efficient. The gases emitted when waste is burned contain hydrogen chloride and other acid gases. To prevent corrosion of boiler tubes, steam temperature can only be raised to a maximum of about 450 °C, thus limiting power generation efficiency to a maximum of about 25%. In contrast, gas-fired and other fossil fuel-fired power plants generate electricity using combustion gases at 1600 °C and can have generation efficiencies exceeding 60%. In addition, as renewable energy becomes more widespread, the time may come when electricity generated by incinerators cannot be sold.

If incinerator boilers are used to supply steam, about 90% of the heat can be used effectively with minimal losses. As the steam used by chemical and other industrial plants is produced by burning fossil fuels, steam produced by incinerator boilers has comparable thermal efficiency. Thus, if heat produced by incinerators is used to supply steam, the energy efficiency is more than twice that of power generation.

Figure 2. Comparison of energy efficiency for generating electricity by waste incineration and using natural gas to supply steam with using waste incineration to supply steam and using natural gas to generate electricity. Efficient use of the steam produced by waste incineration can improve the energy efficiency of society as a whole.

How much waste would be required to supply steam to a petrochemical plant?

While steam supply is possible even on a small scale, the effectiveness is proportional to the amount of steam. The amount of steam supplied needs to be increased to increase the effectiveness. Ideally, one complex would incinerate more than 5000 tons of waste per day. Although the situation varies greatly depending on the petrochemical plant, if a petrochemical plant consumes 1000 tons of steam per hour, incinerating 5000 tons of waste per day might be able to supply about half of the required steam. Although there are differences among cities, if daily combustible waste disposal is around 0.7 to 0.8 kg per capita, a population of 6 to 7 million would supply about 5000 tons of combustible waste per day.

3. The potential of LCCN systems for reducing CO2 emissions is greater than 15 million tons per year

Can we reduce CO2 emissions simply by changing where we burn our waste?

The potential for reduction of CO2 emissions is large. The chemical industry emits approximately 60 million tons of CO2 annually in plastic manufacturing etc1). However, if LCCN systems supplied steam from incinerators, annual emissions could be reduced by about 20 to 25 million tons. Even assuming that the current incinerator waste-to-electricity systems operated by local governments are reducing annual CO2 emissions by 5 million tons, a further 15 to 20 million tons reduction can be expected. Furthermore, the CO2 emissions associated with the increased distance that waste would be transported are insignificant compared to the reduction effect.

If electricity from renewable sources becomes abundant in the future and increasing amounts can be converted into steam, the significance of the waste-to-steam supply system might decline. However, given the current transition period, the system will likely remain relevant until some time after 2050.

Instead of burning waste, shouldn’t we reduce our use of materials and promote recycling?

Although the use of heat from incinerators by factories is progressing in some European countries, there are opinions that waste should not be burned. However, strict separation is essential if high-quality recycled products are to be produced. In the case of polyethylene, it would be necessary to collect only polyethylene; also, given that there are different types of polyethylene, it would be necessary to collect each type separately. The dilemma is that trying to improve the quality of recycled products results in a lot of residual material being produced; it would be counterproductive if we ended up producing a lot of waste by collecting materials for recycling.

To achieve carbon neutrality, “horizontal recycling,” in which materials are returned to the same product, is essential. However, of the plastic food packaging waste disposed of by households, only PET bottles and white polystyrene foam trays are recycled as the same product. There is great potential for recycling, and the benefits of recycling will increase as systems and technologies improve. However, some products cannot be recycled no matter how hard we try; there is no point in producing low-quality recycled products that rapidly become waste.

Photograph 1. Used plastic containers and packaging. As the plastic material is contaminated by foreign matter and plastics of various colors are mixed, if the materials are recycled, the recycled materials tend to be dull in color, and applications may be limited.
Photo Credit: FUJII Minoru, March 2012, Honjo, Saitama Prefecture

Much effort is being made to reduce the use of plastic materials . The use of plastic shopping bags has been greatly reduced, while PET bottles have become thinner. However, it is unclear how much the use of plastic can be reduced in the future. If the LCCN system is implemented, there are no issues if materials are changed. Also, as waste is collected over wide areas, even if the amount of material consumed is reduced, the required amount of waste can be obtained by widening the collection area. I believe LCCN is a realistic compromise as wastes that need to be incinerated can be accepted and managed carbon neutrally. 

Can the CO2 emissions from incineration be captured?

It has been demonstrated that about 90% of the CO2 emitted by incineration can be captured2). About half of the waste currently incinerated is biomass-derived, including paper and food, which can be considered carbon neutral. If it becomes possible to capture 90% of the CO2 emitted for use as raw material for producing plastics, CO2 emissions from the LCCN process will actually be negative if the biomass-derived CO2 is considered.

CO2 capture technology has been around for a long time; for example, the CO2 added to carbonated drinks is captured from factory exhaust gas and other sources. However, as there have not been many uses for CO2, very little CO2 has been captured from incinerator emissions. For example, even if an incinerator is equipped with a CO2 capture device and the CO2 is sent to a nearby greenhouse, only a portion of the CO2 is absorbed by plants. Also, the plants eventually decompose and release CO2. Thus, current CO2 capture and utilization methods cannot be carbon neutral.

4. Securing land to site incinerators and waste collection from a wide area are issues

Given that LCCN systems are needed now, why hasn't commercialization of LCCN moved forward?

We first proposed industrial use of heat recovered from incinerators eight years ago and the construction of large-scale incinerators within petrochemical complexes three years ago. I have been visiting local governments and companies to explain the LCCN concept. Since former Prime Minister Suga Yoshihide announced his “carbon neutral” declaration in 2020, our concept,including expanding the waste collection area for management, is being viewed more favorably.

Photograph 2. Steam conduit of the Kawasaki Steam Net. After partial use for power generation, steam generated by the JERA Kawasaki Thermal Power Station is supplied to several factories in the neighboring Chidori and Yako districts. Compared to each company using boilers etc. to produce steam, CO2 emissions are reduced by about 25,000 tons annually.
Photo Credit: FUJII Minoru, January 2019, Kawasaki, Kanagawa Prefecture

Feasibility studies have been conducted in some areas. However, constructing an appropriately sized incinerator requires at least 2 hectares of land (1 hectare is 100 m x 100 m), and finding land can be difficult. In the future, I think it will be possible to build incinerators on former factory sites that become available due to changes in industrial structure, etc.

There may be opposition from local residents. Although incinerator flue gas is treated to keep emission levels below environmental standards and siting within a petrochemical complex means that the incinerator will be located away from residential areas, transport of waste from a wide area remains an issue. Passage of trucks loaded with large amounts of waste will not be welcomed. One possible solution is taking advantage of the location of petrochemical complexes at ports and transporting waste by ship to the facility.

Another issue is that building an incinerator in Japan takes at least eight years. About six years are required to complete the environmental assessment, and about two years are required for the construction. Given that building large-scale incinerators would require an investment of several tens of billions of yen, if the feasibility of LCCN is unclear, companies will need to take other measures to reduce CO2 emissions. Thus, investments in LCCN may not occur.

You mentioned that using heat energy from incineration by factories is becoming more common in Europe. What about Asia?

Factories in South Korea are already using heat from incinerators. However, the economic conditions in some emerging countries mean that there are very few incinerators. In those countries, the problem is that waste is directly landfilled at disposal sites without being incinerated.

As I mentioned, supplying steam from incinerators to factories is more than twice as efficient as power generation by incinerators. The higher efficiency also means higher revenue from energy sales. Currently, solid waste left at disposal sites has no value. However, if it can be understood that waste can achieve its highest value by being used as energy through the LCCN system, it will become easier for emerging nations to deploy incinerators and contribute to resolving the waste management problem . Feasibility studies have been conducted in India, while discussions have started in Indonesia, Thailand, and China regarding the deployment of LCCN systems.

Please tell us your thoughts on future prospects.

We would like to launch as soon as possible the Joint Regional Manufacturing and Recycling Industries Carbon Recycling Promotion Council (tentative name) with the participation of local government, companies that use steam, industrial waste management companies, research institutes, and other organizations. While promoting collaboration between the areas where petrochemical complexes and large-scale factories are located and the areas that would supply waste, we would like to launch a model business for LCCN as soon as possible.

If incinerators that have reached the end of their service lives are replaced with conventional waste-to-electricity facilities, the deployment of LCCN systems will not progress. It is a race against time; I hope we can all work together to create a path to a carbon neutral future.

(Interviewer: KIKUCHI Nahoko, Social Systems Division )
(Interview Photograph: NARITA Seiji, Public Relations Office, Planning Division)

References

1)Japan Chemical Industry Association "Chemical Industry Global Warming Initiatives : Carbon Neutral Action Plan FY2022 Follow up Report,”METI website, 2023. (in Japanese)
https://www.meti.go.jp/shingikai/sankoshin/sangyo_gijutsu/chikyu_kankyo/kagaku_wg/pdf/2022_01_04_01.pdf

2)Kuchokai Institute for Research and Study,“FY2023 Research Report: Toward local production and consumption of CO2 in the Special wards—CO2 separation and utilization at incineration plants and the role of the 23 Wards¬ ,” Kuchokai Institute for Research and Study website. (in Japanese)
https://www.tokyo23-kuchokai-kiko.jp/report/docs/6fcb3ad193d6cb0d45e827cbb0b0466e26cd56b9.pdf

For further information

-Fujii Minoru, "Investigation of sustainable carbon neutral material production and utilization”Japan Automobile Recycling Promotion Center website, 2022. (in Japanese)
https://www.jarc.or.jp/renewal/wp-content/uploads/2022/10/contribution_004.pdf

-Fujii Minoru,“Circular energy use that achieves both a circular economy and carbon neutrality" Japan Association of Human and Environmental Symbiosis, 24th Annual Conference (FY2021) material, Japan Association of Human and Environmental Symbiosis website. (in Japanese)
https://jahes.jp/images/%E5%9B%BD%E7%92%B0%E7%A0%94_%E8%97%A4%E4%BA%95%E6%A7%98.pdf