“How Much Biogas is needed to make Electricity, or Drive a Car from organic waste?” Is a question often asked. We will provide an answer which has been achieved for one high performance AD plant here, so READ ON!
What ferments longest, in the most optimised biogas plant makes the most biogas…
Watch our video below, which gives an example of how much biogas it takes to make Electricity or Power a Car, before returning to SCROLL DOWN and read our full article which places this video in context and provides the source of the data quoted in the video below:
So, let us look at the example of one German Biogas plant and the answer to the question of “how much biogas”, which they have provided in a Press Release (reproduced with translation from the German original, and with edits, below):
Press Release: Sueddeutsche Zeitung Magazin – By Iris Hilberth, Brunnthal
Biomass Fermentation Plant in Kirchstockach, 2011 to 2016 – Biogas Performance
It is a remarkable fact that five times as much electricity is generated today, as 20 years ago.
Furthermore, it is produced by the plant without significantly raising the feed input, thanks to improved technology. The yield is so well optimised that the operators say that the output could only be further increased if the citizens would separate their garbage more cleanly.
Salad, fruit bowls, coffee filters, kitchen paper or plant remnants; they are all wonderful substances to bring light into the dark. There is a lot of energy in organic waste.
How Much Biogas is Produced from 1 Kg of Kitchen Waste?
One kilo of waste is sufficient to produce 0.07 cubic meters of methane.
How Much Biogas is Needed to Make A Useful Amount of Electricity
One kilo of waste is sufficient to produce electricity that is powerful enough to light an energy saving lamp for 50 hours
How Much Biogas is Needed to Drive A Car a Distance
One kilo of waste is sufficient to produce enough biogas to travel a kilometer, or two kilometers by an eco-car.
This is what is achieved in Kirchstockach, Germany, where the County Council built a biowaste fermentation plant over 20 years ago. The biomass fermentation plant of the Landkreis in Kirchstockach, is operated by Ganser Entsorgung. This is the bio-waste recycling plant of the district of Kirchstockach, Germany.
Since then the annual electricity generation has been quintupled (raised fivefold). After some initial difficulties and technical shortcomings in the first two years, the operating company Ganser recorded in 1999 , after all, 1.12 million kilowatt hours in 2016 to recorded total 5.1 millions. 32 528 tonnes of bio waste were delivered last year, 30.5 of which were converted to 2.5 million cubic meters of biogas for the generation of electricity and heat in the combined heat and power plant. 35 percent of the biogas is converted into electricity and 55 percent can be used as heat. The digestate can be used as fertiliser and peat substitute. [So, clearly, it should not just be a question of how much biogas can an AD plant produce, but also what other valuable products can it also provide.]
According to Landratsamt, last year, 4.1 million kilograms of CO2 would have been avoided. The support of the citizens for this plant is still very good. The authority produces 26,000 tonnes of organic waste which are produced each year from the county, which is 77 kilograms per inhabitant. The state capital of Munich also supplies another 6000 tons in Kirchstockach.
The increase in the amount of electricity has nothing to do with the increase in the amount of waste. [Rather than that, it is a matter of how much biogas is created as a function of AD plant efficiency].
In recent years, there has been further investment in the biogas plant technology. Originally, the plant had only been planned for a throughput of 20,000 tonnes of bio-waste. An expansion to 30,500 tonnes by the construction of a new large hydrolysis reactor in 2010, led to a shorter dwell time of the mass in the reactors. It also led to an increase in how much biogas production is now achieved.
An additional factor in how much biogas is produced was the renovation of the methane reactor, so that the biogas yield in the past year compared to the year 2009 was improved. It rose by 34 percent, from 60 cubic meters to 81 cubic meters per tonne of organic waste.
CHP Use Improves the Carbon Emissions Savings Achieved
The Gymnasium Ottobrunn is also supplied with heat via a CHP heating scheme, and hygienisation of the digestate (pasteurisation) is carried out; after all, it must be free of weeds and pathogens before it can be sold as a soil improver.
The demand for own heat in the plant has been reduced.
According to Managing Director Ulrich Niefnecker, this means that a higher amount of heat is available for transmission to third parties. Meanwhile, a contract on the supply of heat for the Gymnasium Ottobrunn had been concluded with the inclusion of heating to secondary schools in the southeast of the county. For four other schools contracts are pending.
In order to be able to implement a full thermal heat (CHP) utilization at the location, in the short term, 2014 saw the start of a new project. This time not devoted to optimising how much biogas was produced, but to use the heat for the best value.
A pilot experiment with the drying of wood chips and wood chips was undertaken successfully, and the project is now to be continued permanently.
“27 percent of waste heat is used for wood drying, the goal is one hundred percent,” says Niefnecker.
For the wood industry, a practical solution has been developed:
“Dry wood burns better and you can store it without mould developing,” explained the managing director.
The operator of the plant is paid 75 euros per ten cubic meters of wood.
Future Work Needed if Further Efficiency Gains are to be Achieved
According to Niefnecker, the improvements in the plant are currently largely exhausted. However, bio-waste recycling could still be further optimised if the municipalities could segregate the kitchen waste to an even better purity.
“Sand and glass splinters are always there.” said Niefnecker.
In the waste bins sent to the biogas plant there is still land a lot of dirt and material, which does not belong there. The amount of sand that has to be extracted in the plant prior to the processing of the organic waste has increased. It has increased so that it reached a maximum of 2300 tonnes, in 2016 .
This means that 7.5 percent of the supplied so called “organic waste” was sand.
Together with the branches, branches, plastics, stones and light metals which are also not desired, the amount of unfavourable substances is added to 6,192 Metric tons.
“Sand and glass splinter are always there, but we also often find potato peelers, cola cans or batteries,” the managing director said.
Thus, in order to improve the quality of the organic waste, it is necessary to achieve an even better separation of the substances before its introduction into the digester.
For example, green grass, flowers and foliage are the correct organic waste, while branches and logs are not.
Such material is used by the county, but only in other classifications of recycled material. Such unwanted material, should not be placed in garden waste and kitchen waste collections. This also applies to wood, earth, stones, general rubbish.
That’s not all either, and it is a fact which many citizens do not know, probably because it is handled differently in Munich: for eggs and nutshells.
Compostable Plastic Bags for Organic Waste
The operators of the plant also strongly advise against the use of compostable plastic bags for organic waste.
“They are not distinguishable from other plastics and usually are not made from corn starch”, Niefnecker explained.
For that reason technique used by the biogas plant operators, is to pull out all the bags.
“We recommend paper bags”, Niefnecker explained.
Landratsamt now wants to publish a new detailed bio-waste separation list to the municipalities. It also wants to improve the education of the public, to promote a better separation.