Augsuti 2017
Hammarby sjöstad is home to a new modern bus depot for up to 140 climate-friendly biogas buses that blends discreetly into the urban environment. The entire project was challenging and technically complex because the bus depot is being built in the middle of the city, on several levels, some of which are below groundwater level, with commercial premises on top and residential units right next door.
Within this huge project, we were awarded the contract for gas compression, gas storage and four biogas refueling dispensers. With our recently delivered facilities for large bus depots for biogas buses in Gubbängen in Linköping, Bettorp in Örebro, Helsinki and several depots in Stockholm, this project could have been perceived as another in a row. However, this bus depot differs in that all buses will be able to be filled quickly via four dispensers instead of, as is often the case, filling biogas buses slowly via refueling ramps overnight and only filling individual buses quickly when necessary.
Although the total amount of gas refueled is the same, this arrangement creates a much greater challenge in terms of compressors and storage capability. In order to quickly refuel an average of 16 buses per hour and with higher peaks, we have three Pignone compressors that compress the pipeline gas and fill a gas storage consisting of nine storage packages with a total of 135 cubic meters of geometric volume that 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 plant with six Booster compressors that are automatically started via the control system that keeps track of when refueling takes place and on which dispenser(s) to be able to start enough compressors to always maintain minimum refueling times.
To ensure high availability, the compressors' start-up sequence is alternated to maintain the most consistent machine uptime possible. Overall, the combination of gas bearings and boosters brings major benefits for the operation of the compressors and also reduces wear 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 warehouses are located under Hammarbyallén to the four refueling stations in Fredriksdal's state-of-the-art bus depot. We are proud to be able to contribute to making Stockholm's local traffic fossil-free with this complicated and exciting project.
