July 4, 2016
Although the average age of the bus fleet in Polish cities is constantly decreasing, new buses are still fuelled mainly by diesel oil. However, this could be changed easily, as has been demonstrated by cities that have decided to go green and have chosen biogas buses.
This is a repost of Biogazowe autobusy to ekologiczne rozwiązanie dla miast, originally published by Janusz Mizerny (Facebook, Instagram, Google+) and submitted to the Europe in My Region 2016 blogging competition.
What is biogas?
First of all, it must be explained what biogas is, as most people associate it with something organic and, well, something “smelly”. In reality, and in accordance with the Act on Renewable Energy Sources, biogas is gas obtained from biomass, in particular from installations for processing animal and plant waste or waste from sewage treatment plants and landfills. Thus, it is organic. As regards its smell, biogas is odourless, since more than half (50–65%) of its composition consists of methane and 30–45% is carbon dioxide, which are naturally odourless gases. It also contains small volumes of water vapour, oxygen, nitrogen and hydrogen sulphide.
Biogas is produced through the process of anaerobic fermentation by methanogenic bacteria from various types of organic materials, such as agricultural and food waste, animal manure or sewage sludge. Hence, biogas is de facto produced at landfills, agricultural biogas plants and sewage treatment plants. In nature, biogas is formed in swamps and bogs.
Noble biogas — biomethane
Biogas supplied straight from landfill or fermentation chambers can be used as fuel for cooking or heating; however, this is mostly seen in developing countries, such as India or Bangladesh. For biogas to be used as fuel in engines, it must be refined, i.e. purified from unwanted components, so that it consists in 96–98% methane. This is of course achieved through chemical processes, such as absorption and adsorption.
Once biogas is refined, i.e. converted to biomethane that has practically the same composition as the gas used in cookers, it can be compressed and used for various purposes, such as fuel for motor vehicles. At the end of 2014 in Europe there were over 17,000 installations for producing biogas (an increase of 18% compared to 2013) and 367 installations for converting biogas to biomethane (unfortunately none in Poland).
Unfortunately, Poland currently has no legislation that would enable and support the refinement of biogas so that it could be fed into the gas network or used as fuel, e.g. for biogas buses. There are reports that, as part of work on a new act on renewable energy sources, the present government intends to focus on biogas, so maybe it could also concentrate on something that would actually have a positive effect on the environment (as opposed to the destruction of wind energy and rejection of the concept of prosumers). If Poland does not have a good climate for the use of biogas in public transport, where should we look for good examples?
Biogas buses in Lille
Over 25 years ago, the citizens of the French city of Lille started looking for alternative and green fuels to reduce harmful emissions from transport (nitrogen oxides, sulphur oxides, particulate matter). In 1990, the local authorities decided to start using biogas produced at a sewage treatment plant. Instead of combusting it in a flare, they decided to purchase bio-buses. The first four buses fuelled by biomethane were put on the roads in 1994.
In the meantime, half of the bus fleet in the city was replaced with buses fuelled by natural gas and two recycling plants were built in order to manage the increasing amounts of waste. In 2006, the Lille metropolitan area became the main coordinator of the Biogasmax programme aimed at demonstrating the technical and economical feasibility of using waste as source of fuel for vehicles.
As a result of this project, 108,000 tonnes of waste are processed annually, producing more than 4 mln m3 of biogas (which corresponds to 4.5 million m3 of diesel oil). But where are these green buses? In 2005, half of the bus fleet were buses fuelled by gas that were purchased with funding from the Trendsetter programme. Currently, all 430 buses in the Lille agglomeration are fuelled by biogas (partially mixed with natural gas).
Biogas buses in Lille are refuelled directly in three bus depots located next to biogas producing plants. Moreover, since 2011 biomethane produced from waste disposal and sewage treatment is also fed to the local gas network. Some of the biogas is also used to produce electricity and heat, and post-fermentation sludge is an excellent fertilizer. Also, some waste collection trucks are also fuelled by biogas, closing the biogas production cycle.
More and more biogas in buses
Not only the French citizens of Lille have the privilege of travelling by green buses. Last year in the United Kingdom, a pilot route was opened between Bristol Airport and Bath city centre. The biogas bus runs on biogas derived from waste and municipal sewage. It is labelled in a quite characteristic and suggestive way, due to which the town’s residents affectionately call it “Number 2”.
The bus running on human waste became a popular attraction after Bristol won the European Green Capital Award in 2015. After a year of tests, two local transport companies are willing to purchase biogas buses (even up to 130 in total) using a special fund for low-emission vehicles.
The Swedes are also using biogas in urban transport. At the end of 2014, almost 60% of all produced biomethane was used to fuel some 50,000 vehicles, including over 2,300 buses, which constitutes 17% of all buses in Sweden. Biogas buses are operating for example in Stockholm (over 25% of fleet), Malmö and Linköping (here even a train is fuelled by biogas).
Some European cities, such as Bergen and Oslo in Norway, Stockholm in Sweden, Tartu and Tallinn in Estonia, Kaunas in Lithuania, as well as Rzeszów and Toruń in Poland, participated in the Baltic Biogas Bus between 2009 and 2014. The aim of the programme was to minimise the negative impact of urban transport on the environment by reducing greenhouse gas emissions, pollution and noise. The report summarising this programme proves that biogas buses are a worthwhile investment, since most of the above cities have buses fuelled by biomethane or at least with natural gas operating daily. Some of the cities also use hybrid buses.
Last year the authorities of Bergen in Norway introduced a bus setting even higher ecological standards — an electric and biogas hybrid bus. The Exqui.City 24 vehicle manufactured by VanHool of Belgium looks as if it were from outer space — a 24-metre-long combination of a bus and a tram. Its price is also from outer space — 1 million EUR (which can pay for seven Tesla Model X vehicles; however, a bus is able to transport 30 times more passengers). This hybrid, with its futuristic look, is very impressive (as seen on the streets of Malmö).
Biogas buses are green
According to the latest report comparing the impact of using natural gas and biogas as fuels in transport, only biogas buses are fully green compared to buses running on natural gas (CNG or LNG), not to mention diesel oil.
The results of a well-to-wheel analysis, i.e. from the stage of fuel generation, through its production and transport, until its usage in the vehicle, show that CO2 emissions in buses fuelled by natural gas, depending on the scenario, are from 68% to 82% lower compared to diesel oil and CNG/LNG. Interestingly, in accordance with the same report, natural gas used as a fuel emits less carbon dioxide than diesel oil only in the case of passenger cars.
The main advantage of using gas (CNG/LNG or biomethane) in buses is the level of emissions. While in the case of nitrogen oxide emissions there is no difference compared to diesel oil (apart from passenger cars and light commercial vehicles — see table), SO2 emissions are significantly lower — up to 215 grams for each bus with average annual mileage at a level of 50 000 km. On the other hand, data on particulate matter emissions definitely put oil-fuelled buses in an inferior position — gas-fuelled buses emit almost 1 kg (exactly 924 grams) less particulate matter annually.
In terms of operating costs and required infrastructure biogas buses are more or less at the same level as diesel oil-fuelled buses. However, the environmental costs (including impact on human health, cultivation of crops, ecosystems and economic activity) are 3 times smaller in the case of buses fuelled by biomethane compared both to those fuelled by oil and CNG/LNG.
The report clearly shows that biomethane produced from waste or sewage is much more environmentally friendly fuel compared to diesel oil. Particularly in terms of air pollutant emissions, combustion of methane in buses could significantly improve air quality (especially in Poland), as well as reduce carbon dioxide emissions in the transport sector.
Poland did not use its chance to introduce biogas buses
In Poland, the advantages of methane (derived from natural gas or biogas) as a fuel in vehicles are well known — engine noise reduced by half in comparison to diesel engines with the same life, less CO2 emissions and pollution. Although there are 35 Solbus Solcity 18 buses fuelled by LNG in Warsaw, 66 buses fuelled by CNG in Tychy, and 70 in Rzeszów (37% of the whole fleet), it still does not mean that there are any biogas buses used in any of the Polish cities, as the country does not currently have any installations for converting biogas to biomethane.
In 2014, as part of the EU More Balitc Biogas Bus programme, a prototype installation was built in Niepołomice near Krakow using landfill gas for biomethane production. Biomethane produced in this way was used to fuel the Solaris Urbino 12 bus. The findings of the Waśniewicz, Gis, and Menes team showed that the cost of purchase of biomethane based on 1 vehicle kilometre were lower than for diesel oil.
It is obvious that large-scale utilisation of biogas buses requires substantial financial resources for the purchase of a new fleet, adaptation of depots, provision of gas infrastructure and creation of more local sources of biogas. However, in the face of climate change and poor air quality in Poland these costs are fully justified.
The problem, though, is that whenever people hear of a biogas plant, they immediately start to protest. As a result, we still do not have enough sources of biogas, which we use anyway (following purification) only to produce electricity or heat. Also, there is no support from the state in the form of appropriate legislation to facilitate construction of biogas plants or installations for producing and refining biomethane.
Apart from the Gazela and Gazela BIS programmes as part of the Green Investment System designed to co-finance acquisition of low-carbon transport means, there are no factors to promote the use of gas-fuelled buses. Moreover, an excise tax on CNG has been recently introduced, due to which the purchase of buses fuelled by natural gas, which can also run on biomethane, is now totally unprofitable.
A strong political will is required at national and local level to change the image of smoky buses in our cities. We know how to obtain biogas and convert it into fuel. There is no problem with the purchase of buses fuelled by biogas — such buses are even manufactured by the Polish Solaris and successfully sold abroad. Perhaps a significant increase in fees for using the environment and penalties for polluting the air is the only way to ensure the transition towards using biogas as a fuel. It is unfortunate that we still cannot learn from the green experiences of cities such as Lille and Stockholm.