Published in Lõuna-Eesti Postimees By Estonian University of Life Sciences and Võrumaa Arenduskeskus 6th October 2022

Biogas is produced in several locations in Estonia, but production could be even greater in volume. A project is commencing within the framework of which the scientists of the Estonian University of Life Sciences are mapping the possibilities and necessities of producing biogas in south-eastern Estonia.

Both local producers and local governments face the issue of creation of waste that must be handled in one way or another. Why not try and produce biogas from this? According to Rando Värnik, Chair of Economics in Rural Economy of the Estonian University of Life Sciences, the topic of biogas is crucial just at this moment when across Europe, the search is on for new possibilities in order to reduce dependence from Russian natural gas and the interest in the production of biogas is extremely high. Värnik explained that biogas is produced upon the fermentation of organic matter in a closed reactor without any air access. This creates a mixture of methane and carbon dioxide. In this form, biogas can mainly be used only for producing hot water and electricity (or both of them together in a cogeneration plant). Whether it is possible or affordable depends on whether there are any consumers. As it stands, the demand for heat is seasonal.

Mait Kriipsalu, Chair of Rural Building and Water Management of the Estonian University of Life Sciences, said that there are several producers of biogas operating in Estonia, but biomethane – a purified form of biogas – is only produced by a single few companies. The most well-known example of the use of biomethane is found in Tartu inner-city buses which are powered by this ‘green gas’.

An addition to natural gas

According to Kriipsalu, the matters related to the production and use of biogas depend on various nuances. Biogas can certainly serve as an excellent alternative or an addition to natural gas. The easiest possibility to use biogas would be in district heating, but an issue needs to be solved – gas is produced at equal amounts throughout the year, but it is only actually needed during the heating season.

Another issue lies in the raw materials used for producing the gas, i.e. different biowaste. Transporting such waste from too long distances is not feasible, and its quality must be sufficient. “50-80 kilometres is the limit for reasonable transportation,” said Kriipsalu. “Investments in a biogas plant are rather extensive as the technology is expensive, the equipment must be very resilient and high levels of environmental requirements must be met. This field is very dependent on scale efficiency – there is no point in building too small a plant since it would simply not be economically feasible.”

An excellent example of circular economy

The favourite shape of modern economic models is the circle. Producing biomethane from biogas is a great example of circular economy. “Biogas is cleaned of the carbon dioxide contained therein. The result is biomethane, which could be directed to a natural gas pipe, used for filling up cars, or even better, tractors. The fermentation residue is also useful – it would go straight back to the field as a fertiliser or a soil improvement substance. This would serve the exact and precise purposes and definitions of circular economy,” Värnik explained. “Major farms are already on this path. Unfortunately, the production units in south-eastern Estonia, including Võru County, are small. As a smaller undertaking, the production of biogas is not attractive as such. A solution could be joint activities where many small operators join forces for a common purpose by giving their waste for producing biogas and later receiving the fermentation residue. The project now underway is aimed at clarifying the conditions under which these joint activities would be reasonable.”

Where and to what extent do we have the will to adapt?

According to Värnik, a key point is determining the volume of the raw materials required in order to produce biogas – farm slurry (a by-product of agriculture) and biowaste, the actual quality of the raw materials, and where these are logistically situated. This can be used for pinpointing the locations of the potential production plants. “The long-term objective should be producing cleansed biomethane that could, for example, be used in agriculture for replacing diesel fuel in tractors. Currently, we don’t have such tractors working on biomethane on our fields, but the entire inner-city bus system in Tartu is already using this. The entire bus traffic for long routes could also be based on this fuel,” said Värnik. “Tractors working on biomethane are used in Lithuania, and when we discuss the topic of green transition, we should move in the same direction.”

Kriipsalu added that if the research indicates the existence of a sufficient level of raw materials for biogas, the required production technologies can be chosen next. “It is yet too early to state when a biogas plant will start operating in Võru County or a neighbouring county, as the current situation first needs to be mapped. However, I believe that the key to this situation is joint operations – for example, a renewable energy financial community could have much potential,” noted Kriipsalu. “Our farmers are clever. In the light of the new fertiliser and energy prices and more demanding environmental requirements, they could be interested in topics related to biogas.”