POWER-GEN Europe and REWE 2017

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Upgraded Biogas in the Natural Gas Grid, Operational Challenges for Power Producing Appliances (Room Rheinsaal 4)

Since 2016, upgraded biogas has been injected into the Danish natural gas grid. Since then, multiple and larger biogas upgrading plants have been commissioned and are now injecting biomethane in the low-pressure grid supplying larger areas, especially during summertime. As biomethane production exceeds consumption in some areas, injection at higher pressured regional distribution or transmission grids is being planned. All biomethane injected is online verified to meet national standards for gas in the grid. Biogas and biomethane are excellent gas engine fuels for power production. So is natural gas. However, practical operation of power or CHP producing gas engines has shown difficulties in adapting to the possible sudden gas quality changes in the grid. The paper will present examples on measured gas quality at a number of end-user sites. These measurements show that the flows in the grid are plug flow, meaning that significant changes of calorific value and methane number can be seen in less than a minute in natural gas grids including upgraded biogas. Depending on the production/consumption issues and the end-user location, such changes can be seen many times a day. Examples will be presented. This has shown to be a huge challenge for some connected appliances. Especially gas engines are put under extreme pressure to cope with these changes without drop outs of these power producing units. The paper will present operational end-user experience on this and will present leading engine-manufacturer representatives points of view and proposed appliance-oriented solutions for this renewable energy integration and infrastructural challenge.