“How can gas contribute to the success of the energy transition? We are working on making gas more environmentally friendly and transforming our gas infrastructure into a large-scale green-electricity storage system.”
Dr. Jörg Heinen works on the future of the gas infrastructure
Our gas grids ensure energy security by supplying natural gas, but they also have the potential to store green electricity for long periods of time to facilitate the energy transition.
Our natural gas comes from the steppes of Russia, the expanses of the Norwegian part of the North Sea or from the Netherlands. Hidden pipelines run underground, transporting the natural gas from the deposits to consumers. Our gas infrastructure includes highly modern distribution grids consisting of around 100,000 kilometres of pipelines, measuring and control stations as well as underground natural-gas storage facilities.
These grids are becoming increasingly important as the energy transition takes its course. Biogas that has been processed to natural gas quality can be fed into the grids, which then deliver this ‘green’ gas to end customers. Gas grids will be connected even more closely with power grids in the future. For example, surplus power generated using renewable energy sources can be converted into gas, which is then fed into the natural-gas grid. This process is referred to as ‘power to gas’. The power-to-gas process makes it possible to store green electricity in the existing gas infrastructure either seasonally or over the long term, as needed. Alternatively, the green electricity can be used flexibly in other areas, for example, to fuel cars or to supply heat. This makes it possible to use green electricity for other fields of application. This form of connection is also referred to as ‘sector coupling’.
Our aim is to find a way to transport gas reliably and efficiently over the long term; but we also want to ensure that gas contributes to the success of the energy transition and to the efficient use and operation of our gas infrastructure.
The new odorisation nozzle changing system enables optical inspection as well as fast and reliable removal of the injection nozzle.
The injection nozzle releases a so-called odorant which gives the gas an unpleasant smell so that any leakages are easy to detect.
Innovative odorisation nozzle. Natural gas, which is almost odourless, must have a thoroughly unpleasant odour added to it for safety reasons, so that an accidental gas leak can be detected as soon as it happens. This process is called odourisation. Injection nozzles, which extend into the gas line, inject the odorant into the natural gas.
These must undergo a visual examination on a routine basis, as there have been issues with using injection nozzles for the odourisation process in the past. Until now, this had always been a highly labour-intensive operation. The entire pipeline had to be blocked off, degassed and then disassembled in a time-consuming process. This also proved harmful to the environment. A provisional supply was also required in certain circumstances..
We have found a workaround in our research project on odourisation. The new patented ball valve is built by experts from Westnetz in collaboration with a specialist company. The injection nozzle can now be removed from the pipeline with ease thanks to its special design. An additional integrated viewing panel makes visual inspections of the injection nozzle significantly simpler. Defects or contamination can be quickly detected and the injection nozzle can be easily enlarged and replaced if needed. The gas grid no longer has to be blocked off. This means that using the odourisation ball valve simplifies work processes, is environmentally friendly and reduces operating costs.
Four nozzles have already been installed in Westnetz’s gas network. More are planned. “Demand is high, as we receive requests from all across Germany and neighbouring countries in Europe,” says Sascha Niebialek, Project Manager at Westnetz.
Optimised use of gas compressors. innogy operates four cavern storage facilities for natural gas across Germany via Gas Storage NWE GmbH. These are artificial cavities in salt domes, located over 1,000 metres beneath the ground. These caverns can hold about 1.6 billion cubic metres of gas in total – enough to supply 625,000 households for one year. These subterranean storage facilities don’t just help to rapidly and economically compensate for seasonal fluctuations and consumption peaks; they also provide a buffer to relieve strain on gas grids.
Gas must be compressed before it is stored in cavern storage facilities. Natural gas is stored here at a pressure of up to 200 bar, depending on the depth and fill level. This drives up costs: The electricity needed to power the gas compressors represents about 90 per cent of the energy costs for gas storage facilities. We are searching for ways to reduce energy costs at storage facilities within the scope of a research project designed to increase operational efficiency at the facilities.
To run the gas compressors as efficiently as possible, the optimal operating points in the respective compressor map must be known. This represents the stable working range for the compressor operating point, depending on the volume flow and pressure ratio, for example. However, the compressor map is often either not available or only available in analogue form. Digital maps were created as part of the project and by evaluating historical data, while analogue maps were digitalised. Based on these maps, we are creating an optimisation tool that determines the compressor operating mode with the lowest energy requirements for the respective storage process.
We are currently testing out the first version of the optimisation tool within the framework of a pilot project at the Epe cavern storage facility in Gronau, Westphalia. The tool will be used in three further locations once this project has been completed.
“When our optimisation tool is ready, we will know the optimal operating points for all 14 machine units in all storage-specific operating conditions for the first time,” explains Kai Rittinghaus, Project Manager at Gas Storage NWE. “This is how we will be able to considerably reduce the energy requirements of our compressors and thus decrease energy costs. We hope to lower costs by over five per cent in the first optimisation stage.”