Project Proposal

Waste-to-Energy

Technology, Policy &

Investment Perspective

Outline

• Overview of waste management • Waste to Energy Technologies

– Thermal treatment – Biological treatment – Physical treatment

• Policy perspective

Solid Waste (SW)

/Municipal Solid Waste (MSW)

• SW means any garbage, refuse, sludge and other

discarded materials, resulting from industrial,

commercial, mining and agricultural operations, and from

community activities • MSW—more commonly known as trash or garbage—

consists of everyday items we use and then throw away, such as product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances,

paint, and batteries. This comes from our homes, schools, hospitals, and businesses.

Sources of Solid Waste

• Residential area • Market and

Restaurant • Commercial and

Department Store • Institutional area • Industrial area • Agricultural area

Municipal

solid waste

Generation

for selected

large cities in

Asia

Waste Management

Waste management is the collection, transport, processing, recycling or disposing, managing and monitoring of waste materials. The term usually relates to materials produced by human activity, and is generally undertaken to reduce their effect on health, the environment or aesthetics. Waste management is also carried out to recover resources from it.

Waste management concepts

• Waste hierarchy - extracts the maximum practical benefits from products and to generate the minimum amount of waste.

• Extended Producer Responsibility (EPR) is a strategy designed to promote the integration of all costs associated with products throughout their life cycle (including end-of-life disposal costs) into the market price of the product.

• Polluter pays principle (PPP) is a principle where the

polluting party pays for the impact caused to the

environment. With respect to waste management, this

generally refers to the requirement for a waste generator to

pay for appropriate disposal of the waste.

Hierarchy in Solid Waste

Management

1. Waste Avoidance Most desirable 2. Waste Minimization - CT 3. Waste Reuse/Recycling 4. Waste Treatment 5. Waste Disposal Least desirable

Note: Complete avoidance of solid waste generation is not possible

in real world. Not all wastes are technically and economically

feasible to be recycled or treated. Therefore, final disposal is

still required as an essential part of the management at the end

of integrated solid waste management system.

Evolution of Waste Management Concept

Structures of Municipal Solid Waste Stream Western Countries

Prolonged emission of

Plastic

resource

Metals

(Incineration)

Waste

Mechanical Separation

Landfill LFG recovery

Collection

+Aerobic Treatment

Separation after collection

(Mechanical-Biological Treatment) Incomplete reduction of organics MBT

“Mechanical Separation” should be applicable to waste with low water content.

Japan

Paper, Metals, Glass, Plastic resource

Combustibles Substantial reduction of organics

Waste

Sourc e

Landfill

Collection

Incineration

Separation

Few CH4 emission

Separation before collection

Uncombustibles

“Incineration” has been selected due to sanitation of waste with high water

content. Asian Countries Resource

Organics is still valuable

Waste Collection Landfill

Waste situation in Asia

• In Asia, on an annual basis, approx. 4 billion tonnes of solid

waste are generated and MSW amounts to 790 million tonnes. • About USD25 billion are spent for solid waste management

in urban areas.

• On average 50% of residents lack collection services in urban

areas of low and middle income countries

MSW management in Asia • Municipal solid waste composition varies broadly due climatic

and cultural variations (about 50% is biodegradable) • Systems for collection, transportation and disposal are similar • Involvement of formal (public and private organizations) and

informal sector, NGOs and community based organizations, etc. • Industrial waste (hazardous and non hazardous waste) enters the

MSW stream • Disposal of waste electric and electronic equipment

(WEEE) to landfill

Key Features of Integrated Waste

Management (IWM) concept

An overall approach Uses a range of collection and treatment

methods Handles all materials in the waste stream

Environmental effective Economical affordable Socially acceptable

Anticipated Solid Waste Management Condition in

the Future

1. More stringent regulation 2. Increasing public opposition against facility siting 3. Increasing cost of waste transportation

IWM could help reducing the cost 4. Centralization of waste management facilities

Economically driven

Facing Problems in SWM

1. Limited allocated budget for solid waste management 2. Lack of co-operation between local authorities 3. Lack of skill personnel in waste management practice 4. Ineffective waste recycling program/regulations 5. Opposition against waste disposal facilities from

public/communities 6. Lack of public awareness/participation

Waste is not waste

• Waste is a misplaced resource • Waste residues can be converted into

reusable/new materials, energy, and other

products with value • Natural resources are limited and depleted • Mitigation of waste management problems • Waste can be potential sources for resource

recovery

Waste to Energy Quote The old practice of waste disposal has been to dump in

open landfills, which results in garbage in and garbage remains.

The goal for the new millennium must be garbage in and

energy out in an environmentally acceptable manner.

Thermal Treatment of MSW

• Incineration (energy recovery through complete

oxidation): mass burn and RDF • Pyrolysis • Gasification • Plasma arc (advanced thermal conversion)

Overall Review of MSW Thermal

Treatment Technologies

Incineration of Solid Wastes

Incineration is a thermal processing used for reducing volume of solid wastes and recovering energy. In the process, solid wastes are converted into gaseous, liquid and solid conversion products under high temperature (800-1,000° C), with the concurrent or subsequent release of heat energy.

Terms

Burn: to produce flames and heat

Combustion: a chemical process in which

substances combine with the oxygen in the air to

produce heat and light.

Incinerate : to burn something until it is

completely destroyed

Change of requirements to

Incineration disposal technology

Functions and roles widely required in

incineration treatment have changed in response to

the needs of the times…

1950~

Appropriate treatment for sanitation Basic matter

Weight reduction→ 1/10

Weight/volume reduction

Volume reduction→ 1/20 1980~

HCl, Dioxins, NOx… Reduction of environment impacts

2000~

Energy from waste Recycling and resource recovery

Thermal recovery

Example of configuration of typical fully-continuous

stoker-type incinerator

Potential and limitations of

incineration technologies

Potential

Energy recovery from organic wastes Small footprint Only long-term solution for large cities/municipalities Volume and weight reduced (approx. 90% vol. and 75%

wt reduction) Cost can be offset by heat recovery/ sale of energy

Limitations High investment and operating cost Strong opposition from the public/stakeholders Skilled operators are required

Incinerator Moving grate system Rotary kiln system Fluidized bed system

Incineration – Moving Grate

Pros

• Over 900 plants • Over 10 major suppliers • adequate tender competition • Larger unit capacity • less land requirement • Relatively robust for mixed MSW treatment • No requirement of pre-treatment

Cons

• Excess air requirement higher flue gas volume

• High ash production Latest Development

• Over 90% of MSW incineration plants using moving grate technology • Largest plant: 4,300 tpd mixed MSW in Singapore • Largest unit : 920 tpd mixed MSW in Netherlands • Over 100 new plants since 2003

Incineration – Fluidized Bed Latest Development • Mainly for homogenous waste treatment e.g.,

sewage sludge and industrial wastes • Only 2% of mixed MSW incineration plants using

this technology • Largest plant: 200 tpd mixed MSW in Japan • Largest unit: 82.5 tpd mixed MSW in Japan • A few new MSW plants since 2003, but in small

scale Pros • More intense heat and mass transfer • Minimal mechanical moveable parts less

wearing and lower relevant O&M costs Cons • Limited track record for mixed MSW application • Smaller unit capacity larger land requirement • Requirement of pre-treatment • Less robust for mixed MSW treatment

Incineration – Rotary Kiln Latest Development • Mainly for industrial and hazardous

waste treatment, rare for mixed MSW • Generally, combine rotary kiln and moving grate • Largest plant: 900 tpd mixed MSW in Taiwan • Largest unit: 300 tpd mixed MSW in Taiwan • No reported new plant since 2003 • Long retention time favorable to

treat hazardous waste • Flexible in feedstock e.g., solid and liquid wastes Cons • Limited track record for mixed MSW

application/ a supplier key retreated from market

• High O&M costs due to technical problems

encountered for mixed MSW treatment such as erosion of the refractory materials, plastics deposition and clinkering

• Smaller unit capacity larger land requirement

• Less robust for mixed MSW treatment

Energy recovery

• Hot water boiler • Low pressure

steam boiler • High pressure

steam boiler • Electricity • Co-generation

Gasification

Partial oxidation process using air, pure oxygen, oxygen enriched air, hydrogen, or steam

Produces electricity, fuels (methane, hydrogen, ethanol, synthetic diesel), and chemical products

Temperature > 700oC

More flexible than incineration, more technologically complex than incineration or pyrolysis, more public acceptance

Flexibility of Gasification

Gasification Latest Development ~90 plants worldwide

Largest plant: 405 tpd mixed MSW in Japan Largest unit: 150 tpd mixed MSW in Japan Over 20 new plants since 2003, but

in small-scale Limited air requirement less volume

of flue gas for treatment

Potentially higher flexibility in energy recovery Cons

Limited track record for mixed MSW application/ a key supplier retreated from market

Concern for operation failure (e.g. unpleasant experience in Germany)

Smaller unit capacity larger land requirement

Less robust for mixed MSW treatment Requirement of pre-treatment

Pyrolysis

Thermal degradation of carbonaceous materials Lower temperature than gasification (750 –

1500oF) Absence or limited oxygen Products are pyrolitic oils and gas, solid char Distribution of products depends on temperature Pyrolysis oil used for (after appropriate post-

treatment): liquid fuels, chemicals, adhesives, and other products.

A number of processes directly combust pyrolysis gases, oils, and char

Pyrolysis

Plasma Arc

Latest Development ~30 pyrolysis plants Largest plant: 160 tpd mixed MSW in Japan Largest unit: 80 tpd mixed MSW in Japan Less than 10 new plants since 2003

Temperatures 4,000°C to over 7,000 ° C

Hazardous & toxic compounds broken down to elemental constituents by high temperatures

Organic materials are converted

to fuel gases

Residual materials (inorganics, heavy metals, etc.) immobilized in a rock-like vitrified mass which is highly resistant to leaching

Comparison among Incineration,

Gasification, Plasma Gasification & Pyrolysis

Criteria Moving grate Gasification Pyrolysis

Environmental Factors

Flue gas volume High Medium Low

Ash production High High Medium

Engineering Factors

Flexibility Good Poor Poor

Track Record/Operation Experience Longest Limited Limited/Rare

Reliability - Treatment capacity Largest Medium to small Small

No. of key supplier Many Limited Rare

Land requirement Low Medium Large

Capital and O&M cost Low High High

Biological Treatment Process

Biodegradable waste

• Biodegradable waste is a type of waste which can be broken down, in a reasonable amount of time, into its base compounds by micro-organisms and other living things.

• Biodegradable waste can be commonly found in municipal solid waste (sometimes called biodegradable municipal waste, or BMW) as green waste, food waste, paper waste, and biodegradable plastics. Other biodegradable wastes include human waste, manure, sewage, and slaughterhouse waste. In the absence of oxygen, much of this waste will decay to methane by anaerobic digestion.

Type of biological treatment process • Aerobic Composting

– Need more space and time consuming – More energy & manpower required – O&M problems – Odor problems, high moisture content of waste

• Anaerobic Digestion – Higher net power generation – Lesser plant area required for a continues operation – Greater volume reduction in MSW – Organic stabilization and pathogen reduction

Bio-methanization may be the attractive alternative in Asian countries where higher organic fraction exist.

Anaerobic Digestion of Solid Wastes

The biodegradation of organic wastes by microorganisms

under anaerobic conditions in anaerobic digester will give

final products as biogas (mixture of methane and carbon

dioxide) and anaerobic sludge.

Technology options: - One-stage anaerobic digestion system

Wet process 10-15% TS Dry process 20-40% TS

- Two-stage anaerobic digestion system - Batch system

System Components of AD Plant

DRIVING FORCES BEHIND THE GROWTH OF

ANAEROBIC DIGESTION OF ORGANIC WASTE

• Introduction of Bio-waste collection

• Incentives for production of renewable energy • Sustainable plants ‘win’ more municipal waste procurements

• Advantages of AD – Economically very attractive – No excess wastewater for dry systems: partial

stream digestion – More waste can be treated on the same surface area – Reduction of odors – Hygienization: important for food waste – High flexibility

Potential and limitations of AD technologies

Potential

- Recovery of energy from solid wastes - Simple operation and maintenance (compared

to incineration) - Utilization of organic residue as compost

Limitations

- High investment cost (for large scale AD) - Difficulties in preparation of feedstock (poor upstream management)

How is biogas produced? Biogas occurs widely in nature. Biogas

forms wherever organic material accrues

under exclusion of oxygen (called anaerobic

digestion), e.g. in bogs, on the bottom of

lakes or in ruminants’ stomachs. The organic

matter is almost entirely converted into

biogas in these conditions. The actual

process by which biogas forms involves the

complex interaction of various

microorganisms and takes place in basically

four separate phases

End product = Biogas Composition:

50 – 75 % methane (CH4)

25 – 45 % carbon dioxide (CO2) 2 – 7 % water (H20) < 2 % oxygen (O2)

< 2 % nitrogen (N2) < 1 % ammonia (NH3)

< 1 % hydrogen sulphide (H2S)

The energy content of the biogas is directly dependent on the methane content.

The higher the content of substances such as fats and starch that are easy to break down in the fermented mass, the greater the gas yield.

One cubic meter (m3) of methane has an energy content of about ten kilowatt hours (9.97 kWh).

If the biogas contains 60 % methane, then the energy value of one cubic meter of biogas is about six kilowatt hours. In this case, the heating value of one cubic meter of biogas is roughly 0.6 liters of heating oil.

50

Energy equivalents • 1 Watt = 1 joule second-1 • 1 Wh = 1 x 3600 joules (J) • 1 kWh = 3600000 J • 1 kWh = 3.6 MJ • 22 MJ (1m3 biogas) = 22/3.6 kWh = 6.1 kWh • Electrical conversion efficiency = 35% • Therefore 1m3 biogas = 2.14 kWh (elec)

To get a good combustible gas, the “raw” biogas is cooled, drained,

dried and cleaned from H2S because of its corrosive effect. The obtained gas can be either applied directly or upgraded to natural gas standard – biomethane (98 % methane).

Biogas:

• Production of electricity and heat (cogeneration) • Production of electricity alone • Production of heat alone

Upgraded biogas (biomethane):

• Injection in the gas grid

• Transportation fuel

• High tech process energy

• Raw material for the chemical industry

Biogas yield and methane content of various substrates

Differentiation Wet and Dry

Fermentation • Wet fermentation DM-content of the substrates does not exceed 15 % Pumpable substrates or mixtures Usually continuous processes

• Dry fermentation DM content exceeds 15 % (DM contents of 35%

or more can occur Stackable substrates or mixtures Usually discontinuous processes

Advantages and disadvantages of

Different systems

One Stage System Two-stage system

Continuous

system

Advantages Simple, low-tech, Process stability, Could treat large

cheap, smaller reliable process, amount of waste

heat requirement higher biogas

yield,

Disadvantages Clogging, need Higher cost of Low process

bulking agent, risk investment, efficiency, poor

of explosion complex biogas yield

during emptying a operation,

reactor, poor expensive waste

biogas yield handling

equipment

Delivery of Organic Waste

Bio-Waste Treatment

Examples for Substrate Feeding

Mixing Options

• Passive mixing due to thermal convection • Active mixing

– Mechanical mixing systems • Reel agitator • Paddle agitator

– Propeller agitators • Submersible motor propeller

agitator • Tube screw pump

– Hydraulic circulation • Circulation pump

– Circulation by biogas • Active systems (gas injection)

• Passive systems (pressure balance)

Removing of Solids from the

Reactor

Fermenter Heating

Example for Fermentation

Residue Storage

Fermentation Residue

Utilization

Waste to energy and fertilizer

project

Conclusion

A basic requirement for successful implementation of WtE is the

existence of an advanced waste management system which is

based on the separate collection and treatment of different source

separated waste streams. Bio-mass such as kitchen and garden

waste are digested and/or composted. Recyclables such as paper,

card-board, PET, glass, metals etc. are sorted and directed to the

recycling industry. The management of hazardous waste is

controlled. Remaining MSW fractions which cannot be recycled

are disposed of in a controlled landfill. International experience indicates that the implementation of state

of the art co-processing and landfill gas collection can be

successful if a systematic waste collection exits and some selected

waste streams such as tires or biomass can be directed to the

facilities. Anaerobic digestion requires separate collection of

biomass because any contamination with other MSW fractions

may cause problems with the process and the use of the diges-tion

residues in agriculture. On this waste management level the

suitability of incineration should be assessed in detail before a

project is initiated - some improvements of the waste management

system might be required.

***End***

Thanking You

RPG Group

Raymond Tech Australia

155A, March Street, Richmond Sydney, NSW 2753,Australia

Email: ray@raymondtech.com.au

www.pillaygroup.com.au