Because of Municipal Solid Waste (MSW) containing a share greater than 50% of biodegradable materials, it is classed as a renewable energy source.
Landfill is the Past
Incineration is The Present
SynGasGeneration from Waste is the Future
Current situation and development of Waste Management
Over the past years considerable efforts have been put into disposing municipal, industrial and agricultural waste with minimal expense worldwide. According with the principle “out of sight is out of mind” waste was simply dumped on landfill sites or at sea. Only with growing environmental awareness and an increase in ecological movements the attitude has changed and new ways of waste disposal have been attempted. Setting up comprehensive recycling schemes to recover some of the raw materials is one of them:
However, these systems have their limitations and from an economic point of view a total recovery is impossible: rest-waste remains and needs deposited. Due to waste disposal areas in industrialized countries exceeding their capacity limits, the remaining quantity of waste is being reduced by incineration. Since the 1970’ies massive incineration plants have been built in all industrial countries and meanwhile in developing and newly industrialized countries as well.
Politics and Waste Management
Generally speaking, waste disposal belongs worldwide to the responsibility of the Executive implemented by the conditions imposed by the Legislative. Even though waste disposal is a government task, it is executed by various organizational forms that vary widely between industrialized and developing countries.
It is characteristic for industrialized countries to contract out waste disposal to the municipality or to private companies. The complete set of tasks (collecting, sorting, depositing, incineration) is financed by a long term fee model using various company strategies.
Private sector – – – Profit Maximization
Municipal and Public sector- – – Reducing Expenses and Fees
Despite different objectives, both legal forms are interested in an efficient and profitable recovery of the accumulated waste.
Developing and newly industrialized countries
By comparison, the recycling rate through incineration in developing and emerging countries is minimal. Considering that the volume of waste per capita is still lower than in developed countries, an above-average growth rate of amounts is expected with increasing prosperity. These quantities are still largely deposited due to (still) missing recovery capacities.
Because in these countries politically overall great efforts are made to improve the living standards of the population, it is particularly with the presently available technology no longer considered appropriate to not recover raw materials contained in waste.
No matter where landfills are located, they will represent an environmental problem in the long term that will burden the next generations.
The aim of the current policy should therefore be:
- to curb waste volume growth
- to increase the degree of recyclability through reuse, composting and others
- to feed back the currently still not reusable residual amount (R5) into the economic cycle efficiently and with minimal environmental impact.
Due to the ever-growing cost of waste disposal and the increasing environmental risks associated with sprawling landfills, research is being done to improve the techniques of waste disposal. Goal is to increase the energy efficiency of equipment and systems and simultaneously reduce the environmental impact.
The contemporarily dominant technology is incineration in modern waste incinerators. This technology is constantly improved by the manufacturers, so that with the installations of the 4th generation (2.4 KVA) we can speak of state of the art.
With further development the following main trends are identifiable:
1. Improvement of combustion technologies
- Optimization of grating
- High quality materials for higher temperatures suitable
2. Flue gas cleaning
- Reduction of energy expenses
- Boost of the degree of cleaning
3. Power generation
- High-temperature steam turbines
Due to technologically driven boundaries the electrical efficiency of most of this modern equipment scores between 20-30%. Moreover, with this technology up to 10% of the initial quantity of the waste remains in the form of ash and slag and still must be deposited.
The so-called zero-waste movement has the goal of reducing global waste. The approach is to use recyclable materials in the manufacturing process in conformity with the waste management pyramid. These efforts are sometimes quite successful, but are unable to solve the fundamental problem.
As a result of political requirements as well as technical achievements, the amount of the first four R’s is constantly increasing; nonetheless, the amount of waste to be disposed of is still growing worldwide. With the volume trends within the EU as one of the developed regions, the currently economically viable recycling rate is at a maximum of 50-70%.
The zero-waste movement remains an unreachable goal yet for a long period of time, at least for the next estimated 15-20 years. However, a new approach of waste management is going to be explained in more detail. While today’s core technology of waste management is recycling and incineration, the combustion is going to be substituted by Syngas Generation.
Customer demand for efficiency and sustainability
Municipalities, businesses, agriculture and forestry face a common problem of
- law compliant
- efficient and
disposal of waste in their area on a daily basis
The procedures must meet the following minimum requirements:
- all national and local environmental conditions
- be as simple and straightforward as possible
- be so efficient that a positive operating result can be achieved on the long term
- the final product must be sellable on the long run
In times of scarce funds, growing environmental regulations and political uncertainty, we will have to go new ways to comply with the provisions and the law as well as achieve a break-even or positive operating result. This requires a new perspective on the waste product:
Waste should not be seen as an annoying by-product –but as a tradable material after its treatment and as a resource for profit oriented recycling management.
Types of waste around the world
Worldwide, there are several hundred different types of waste of which some occur more regionally (e.g. waste from oil sand extraction in Alberta, Canada), some have only marginal importance (e.g. remains of shells from processing almonds in California, USA), or some require special disposal procedures (for example medical radioactive waste).
However, the present study only deals with the waste situation for combustible waste with a focus on municipal solid waste.
Current disposal methods
All waste products, that could not be recycled in one form or another, were and still are disposed of as follows:
Disposal on landfills
Oldest and currently still most common method
- Long-term effects on air (out-gassing of methane) and groundwater
- High consumption of land in sensitive areas
Dumping at sea
- Has been a common method for a long time especially for the disposal of hazardous waste
- Is regulated and prohibited for household waste in the EU by international and national laws (e.g. OSPAR agreement)
- Is strictly monitored by coastal protection, marine and satellites and no longer statistically significant
- Combustion in the free field is still common practice for the disposal of agricultural waste
- Combustion in so-called waste incineration plants, currently the world’s most common procedure to reduce waste
- Waste incineration in cement production and incineration of sewage sludge in sludge incineration plants
All of these disposal procedures have the stigma that the disposed substances are not or only partly fed back into the material and energy cycle. Consequently, valuable raw materials are destroyed and lost.
Composting / Fermentation
Composting of biogenic waste to the later reintroduction into agricultural and horticultural land
- Fermentation of liquid or semi liquid and solid waste in gas tanks for the production of gas, which is then used to produce heat and electricity with gas engines