In Hammarby sjöstad lays a new modern bus depot for up to 140 climate-friendly biogas buses that blends discreetly into the urban environment. The whole project was challenging and technically complicated because the bus depot is being built in the middle of town, on several levels, some of which are below ground water level and with commercial premises on top and residences right next door.
Within this giant project, we received the contract for the gas compression, gas storage and four dispensers for the biogas refueling. With our recently delivered facilities for large bus depots for biogas buses in e.g. Gubbängen in Linköping, Bettorp in Örebro, Helsinki and several depots in Stockholm, this project could have been perceived as another in the series. However, this bus depot is distinguished by the fact that all buses must be able to be quickly fill via four dispensers instead of, as is often the case, slowly filling the biogas buses via refueling ramps overnight and only quickly filling individual buses when necessary.
Even if the total amount of fueled gas remains the same, this arrangement creates a much greater challenge in terms of compressors and storage possibilities. In order to be able to fast refuel an average of 16 buses per hour and with higher peaks, we have three Pignone compressors that compress the pipegas and fill a gas storage consisting of nine storage packages with a total of 135 cubic meters of geometric volume, which at storage pressure holds almost 30 tons of biogas. In order to maintain a high pressure even when the number of refueled buses per hour peaks, we have designed the facility with six Booster compressors that are automatically started via the control system that keeps track of when refueling takes place and at which dispenser(s) to be able to start enough compressors to always maintain minimum refueling times.
To guarantee a high availability, the start sequence of the compressors is switched to maintain as even an operating time on the machines as possible. The combination with gas storage and boosters brings overall great advantages for the operation of the compressors and also reduced wear and tear on other components, which in turn increases the availability of the plant.
With all this in place, only the last bit remains, which is to lead the gas from the Mårtensdal side, where our compressor houses and gas storage are, and under Hammarbyallén, to the four refueling places in Fredriksdal’s state-of-the-art bus depot. We are proud to be able to contribute to making Stockholm’s Lokaltrafik fossil-free with this complicated and exciting project.