UPDATE: World’s first CO₂ Bus A/C cools in Berlin

As the world’s first local transport provider, Berliner Verkehrsbetriebe (BVG) is using mobile air conditioning (MAC) systems based on the natural refrigerant CO₂ in seven of its urban buses. If results from real-life tests are satisfactory, BVG is open to install R744 air conditioning in all city buses. On 2 July, BVG presented the concept during a press conference that was attended by BVG, the German Federal Environment Agency UBA and German environmental group DUH.

BVG’s proactive decision to replace the HFC chemical R134a with the 1.430 times less climate damaging CO₂ in its cooling system was lauded by UBA President Flasbarth as being one of “farsightedness”. Although for buses there is not yet a direct regulatory pressure to switch refrigerants, Flasbarth urged other public transport providers to follow Berlin’s move and adopt R744 MAC as a standard as early as possible. DUH President Resch strongly welcomed the decision to test CO₂ systems under tough real-life conditions, expressing his hope that results from this first test could be used to accelerated and optimise its installation in all urban buses and coaches. BVG – that had already retrofitted its buses with diesel particulate filters ten years ago when the automobile industry had still strongly opposed this measure – would now again be showing environmental leadership. Manufacturers of passenger cars would need to follow this courageous step to invest in the only viable alternative to chemical refrigerants, DUH urged.

CO₂ put to the test

The CO₂ MAC systems will be used in seven “LowEntry” Citaro models operating on different routes all around Berlin. As confirmed by BVG towards R744.com, buses running in Berlin cover an average distance of 200 km every day. With peak distances of up to 400 km without any interruption, Berlin’s buses must rely on the most robust and efficient technology available, especially under currently hot summer conditions. BVG expects to publish first results regarding cooling capacity, reliability and durability of CO₂ MAC by this autumn, and hence actively contribute to its optimisation and rapid serial use.

CO₂ MAC expert Konvekta has supplied the innovative R744 systems. After a first initial test with one system installed in a city bus had brought highly positive results, BVG decided to invest in a broader-scale test by equipping six more buses with R744 systems in May.

Konvekta, however, has realised that despite the currently great interest of many traffic organisations in CO2 air conditioning systems, there still persists a fair amount of uncertainty and misinformation on the market. For this reason, the company has decided to offer workshops for bus manufacturers and bus operators, concentrating exclusively on the economic advantages as well as on the functional and maintenance advantages of CO2 air conditioning systems – in theory and practice.

100 tonnes of leaked refrigerant from buses

The use of more environmentally friendly refrigerant is urgently needed given that bus MAC today already contribute a very high share to overall emissions. While in 1993 only 5% of all new city buses in Germany were equipped with an air conditioning system, this figure rose to 64% in 2008. 100% of all long-distance coaches today are equipped with A/C. At an average leakage rate of 13.3% for new coaches and 13.7% for new city buses, all German buses together emitted 100 tonnes of R134a in 2008 alone. This is the same as 140.000 tonnes of CO₂ equivalents every year, or the total tailpipe emissions from 90.000 efficient small cars.

Meanwhile, leading daily DIE WELT, leading automotive magazine Auto Motor Sport and radio station Deutschlandfunk have put a spotlight on German carmakers that had twice publicly promised to use CO₂ MAC in passenger cars but had recently performed a u-turn.

The Dutch website RCC K&L, specialised on the HVAC industry, picked up the topic and translated the article into Dutch. See the link below under "more information".