The affordable and green compressed natural gas (CNG) has become an alternative to petrol and diesel fuel. Biomethane, also called green gas, is a fully renewable fuel which has been produced in Estonia since 2018.

Kadri Penjam

The use of CNG fuels and biomethane has increased in the world as well as in Estonia. Four biomethane production plants are operating in Estonia by now: the first companies that started producing biomethane in 2018 are OÜ Rohegaas in Kunda, which makes it from sewage sludge, and OÜ Biometaan in Koksvere, Viljandi County, which gets its raw material from manure and biomass. OÜ Vinni Biogaas and OÜ Tartu Biogaas launched their production this summer. Both plants produce biomethane from manure, biowaste and food industry residues.

Everything that ferments can be used as raw material for biomethane. Manure, silage, cut grass, vegetable tops, restaurant waste, residues of cleaning granaries and of the dairy, bread and meat industries – everything that is of organic and biological origin can be used. Head of the production plant of OÜ Biometaan Ahto Oja explains that they produce biomethane from agricultural waste and cattle slurry: “We have 1700 dairy cows whose slurry we use alongside the manure of young and other farm animals and silage. We have a storage tank for solid raw material that can hold 30 tons. From there, the solid mass moves to the mixing facility. Liquid raw material is initially stored in a tank to which it is pumped straight from the barn.”

According to the CEO of OÜ Rohegaas Marko Tiiman, they produce biomethane from the biogas obtained from the wastewater of AS Estonian Cell. In his opinion, the need for biomethane on the local market has increased constantly over the years: “OÜ Rohegaas is the biggest biomethane producer in Estonia. We process about 5.5 million cubic metres of biomethane, which is enough to keep all the buses of Pärnu and Tartu, and also partially the buses of Tallinn, going for years.”

The fact that after many years, local fuel is produced in Estonia again – biomethane, which is used as vehicle fuel – is extremely important to the energy economy of Estonia. It also helps us achieve renewable energy goals as well as reduce greenhouse gas emissions and the use of fossil energy sources in Estonia.

There are certainly many people who are interested in how biomethane is actually produced and what this gas is all about.

Basically, the production of biomethane imitates the operation of a cow’s stomach. The temperature in the production tank without oxygen is 37–40 degrees; bacteria break down the biomass and turn it into biogas. This contains 50–60% methane and the rest is mostly carbon dioxide. After its removal during the biogas cleaning process, we get biomethane, which contains 96–98% of methane and in terms of calorific value is equal to natural gas, which contains 96–98% of methane. For example, 3,600 m3 of biofuel per day is produced at the production plant of OÜ Biometaan in this manner.

There are many false perceptions and misunderstandings that must be refuted. For example, people think that gas cars smell more than others, filling the car with fuel is difficult or it does not run as well as other vehicles. The truth is that gas fuel is safe to use, it’s not toxic and the CO2 emissions of CNG are approximately 25% lower than in the case of petrol. Biomethane is a zero-emission fuel, which makes it fully environment friendly.

The way in which methane fuels burn in the engine is cleaner and using them can reduce global carbon dioxide emissions and air pollution. Fewer sulphur oxide (SOx) emissions, which may form acid rain when mixed with water, are generated during incineration. Nitrogen oxide (NOx) emissions, which cause lung and heart disease when emitted into the air and are the main component of smog, will also decrease considerably. Only carbon dioxide and water vapour are left after CNG is fully incinerated. Toxic carbon monoxide and nitrogen oxide, carbohydrates, soot and other fine particles are emitted in addition to when CO2 petrol is used.

The fuel consumption of ordinary consumers using methane fuel in their vehicles decreases by half on average. All of this together is a big step towards a more environmentally sustainable future.

 You care about the environment when you use green fuel. At present, there are 20 CNG stations in Estonia that offer biomethane. There will be more of them in the coming years. Compressed gas or biomethane, i.e. green gas, is more affordable: driving 100 km with CNG will cost you approximately three euros. We are more environment friendly when we prefer vehicles that consume biomethane and reduce the footprint we make with our activities. It’s important to keep in mind what kind of an environment we leave to the next generations.

A massive step in the right direction has been taken in the Estonian public transport sector as well: the buses used for city routes in Tartu and for city and suburban routes in Pärnu as well as the public transport vehicles in Saaremaa and Võru have mostly been using fuel with biomethane certificates for some time now. The first buses that consumer fuel with biomethane certificate recently appeared on the streets of Tallinn as well. The use of CNG fuel reduces the footprint of public transport considerably.

Project Manager of Tartu City Government Jaanus Tamm explains that the introduction of buses that use biomethane is a result of efforts that took 10 years and a massive step towards carbon neutrality. Tartu is one of the few cities of its size in Europe where public transport is fully carbon free.

Buses that use green gas have been driving in Pärnu for a couple of years now. CEO of the Pärnu County Public Transport Centre Andrus Kärpuk confirms that green gas has been used in Pärnu city buses since 1 May 2018 and in suburban buses since 1 November 2019. “To be the first is a great responsibility as well as a great honour,” he admits. “The decision was easy to make due to the financial support of the EU Cohesion Fund.”

Andrus Kärpuk adds that the transition to green energy was a question of reputation for Pärnu, as a resort starts from conservation and a green mindset. Secondly, it’s an exciting innovation that gives pride to the locals and evokes curiosity in tourists. “Thirdly, who and when should achieve the European Union’s renewable energy transport goal if we don’t do it ourselves and right now? Fourthly, environment-friendly and innovative solutions make public transport more popular, which is a necessary step towards making transport solutions more sustainable. Our experience so far has indicated that we’re on the right track,” explains Andrus Kärpuk.

Environment-friendly circular economy that already works. So, in addition to saving money, the production of biomethane is a step towards a cleaner environment. Many people are still only talking about the circular economy, but the production of biomethane from agricultural waste is a true example of the practical circular economy.

Organic waste is used to produce biomethane. Whether it’s an apple core or manure – everything can be used to make biomethane. The fermentation of organic waste generates biomethane as well as the solid and liquid fermentation wastes used for land improvement and as fertilisers, the nutrient content of which is comparable to that of manure, but it does not smell or soil and is similar to peat. A remarkable share of public transport vehicles in Estonia already use biomethane and the air is cleaner when methane fuels are used. This type of fuel is a smaller burden on the environment as well as on our wallets.

Kadri Penjam (1980) works in the area of communications and as a freelance journalist.