What is organic waste?
Organic waste is defined as residual plant and animal matter. This waste contains stored solar energy in the form of carbohydrates, fats and proteins. Treated appropriately (e.g. fermentation), biogas can be sourced from this waste.

How is biogas converted into electricity and heat?
Electricity and heat are produced from biogas in a cogeneration unit. The central component of a cogeneration unit is a combustion motor which drives a connected generator. In turn, it produces the electricity which is then fed into the grid. The heat from the motor can be collected via a heat exchanger and fed to a heating system.

Why do you have to pay to dispose of organic waste?
Investment and operating costs are incurred as well as collection and transport costs. As the sale of energy and material end products does not cover these costs, fees for sacks and containers must be charged.

What can be disposed of in green waste?
Garden waste: - Lawn and meadow cuttings
- Bush and tree clippings
- Flower and vegetable shrubs
- Leaves, weeds and windfall fruit
- Balcony and potted plants
Household waste:- Food preparation waste from fruit and vegetables
- Coffee grounds and tea leaves
- Pet droppings and cat litter
- Eggshells
- Compost bag
Food leftovers
- Fruit, vegetables, salad
- Bread and baked goods
- Cheese, various fats
- Fish, meat

What cannot be disposed of in green waste?
- Plastic, non-biodegradable string
- Stones, glass
- Medicines
- Metal, aluminium, tin cans
- Textiles, vacuum cleaner bags
- Batteries
- Mineral oil
- Road sweepings, ashes

Are Kompogas plants available for private households?
No. While very small plants are available for farms, mini-fermentation plants for private households are not worthwhile (yet).

What are the advantages/disadvantages of fermentation compared with composting?
Fermentation produces CO2-neutral biogas, which can be fed into the natural gas network or used to generate electricity and heat. Thus, fermentation technology permits decentralised waste recycling combined with energy production. However, the capital investment required for fermenting is greater than that for composting.

What makes Kompogas CO2-neutral?
Organic waste consists of plants. These plants have absorbed CO2 from the atmosphere to grow. When treating and incinerating the biogas, the same quantity of CO2 is released again into the atmosphere. That makes Kompogas CO2-neutral.

How far are the transport distances between the community and the plant?
The catchment area of an average plant is within a radius of approx. 25 km.

How is raw gas treated to natural gas quality?
Treatment to natural gas quality can be divided into roughly 3 process steps.
1) Drying: In the first phase, the raw gas is dehydrated.
2) Desulphurisation: In the next step, the sulphur is removed from the gas.
3) CO2 precipitation: By pressure swing adsorption or amine scrubbing, the CO2 content is reduced in a final step to increase the methane content. After this, the methane content is at least 96%, and matches the natural gas quality.

How can I source green electricity for my household?
Green electricity can be ordered from your power supply company.

If I choose electricity from renewable energy sources, do I need a special electricity power line?
No, when you choose green electricity, you help pay for production of electricity from renewable sources.

If I use gas as a fuel, how much of it is biogas?
If you fill your tank with natural gas/biogas, at least 10% is usually biogas. In Otelfingen in particular, gas is 100% biogas, while the percentage in Rümlang is between 40% and 80%.

What are the advantages of fermentation compared with incineration?
One major advantage of fermentation is the preservation of the nutrients. The closed cycle allows the organic fertiliser to be spread on the soil or re-used for agriculture again. A second advantage of fermentation compared with incineration are the lower collection fees for organic waste. Also, biogas can be stored to a limited extent, by contrast to heat.