Danish Gas Technology Centre has been carrying out a feasibility project to clarify the possibilities of in-stalling gas expanders at M/R-stations (Measuring and Regulating) in the Distribution system of the natural gas grid. A large number of such expanders are installed around the world.
Project description
Danish Gas Technology Centre has been carrying out a feasibility project to clarify the possibilities of installing gas expanders at M/R-stations (Measuring and Regulating) in the TRANSMISSION system of the natural gas grid. A large number of such expanders are installed around the world. The novelty of this project is to use a heat pump to perform the necessary heating of the gas before the expander, and to ''export'' to the electricity grid the remaining electricity from the generator connected to the expander. This former project treated the large M/R-stations where pressure is reduced from 80 bar to 40 or 20 bar, respectively. The present project will treat the small M/R-stations at the gas DISTRIBUTION grid where pressure is reduced from 40 or 20 bar to 4 bar. The volume flow is far smaller in these stations and the number of stations is much larger. The preliminary project (year1 of project) will investigate whether components for such smaller systems can be found, and it should investigate prices for different quantities. A technical feasibility study will be done. Also, preliminary calculations of payback times will be carried out. A large potential of CO2-reduction is present with this technology based on saving of natural gas combustion and on new electricity production displacing existing production without any use of primary energy. If the preliminary project proves successful a full project will be started up, including installation at an M/R-station
Results
Danish Gas Technology Centre has been carrying out a feasibility project to clarify the possibilities of in-stalling gas expanders at M/R-stations (Measuring and Regulating) in the Distribution system of the natural gas grid. A large number of such expanders are installed around the world. The novelty of this project is to use a heat pump to perform the necessary heating of the gas before the expander, and to “export” to the electricity grid the remaining electricity from the generator connected to the expander. The present project includes the small M/R-stations at the gas Distribution grid where pressure is reduced from 40 or 20 bar to 4 bar. The preliminary project (year1 of project) has investigated whether components for such smaller systems can be found, and it has investigated prices for different quantities. A technical fea-sibility study has been done. Also, preliminary calculations of payback times have been carried out. A large potential of CO2-reduction is present with this technology based on saving of natural gas combustion and on new electricity production displacing existing production without any use of primary energy. The main results and conclusions are: • There are component suppliers for expander systems suitable to the size of distribution network M/R stations. • Pressure regulators provided at the stations are laid out with significant overcapacity, enabling a simplified installation of the expander systems. • If the system is being rolled out across the Danish distribution grid, the realistic saving potential is approx. 2.3 million Nm3 of gas per year and a production of almost 40 million kWh of electricity. • The realistic potential which includes the most suitable stations counts for approx. 35 to 40% of the technical potential. • DSM-committee (Energy-saving effort in Denmark) has indicated that both the saved gas at the station and the exported electricity can be included in counting of savings. It has a value equal to 15% of purchase and installation price of the system. • The feed-in tariffs in Denmark for electricity produced by a ZEGEX plant are not cer-tain. If the price were 0.60 DKK/kWh for electricity sold, the simple payback time would be 6-7 years on average, covering a variation from 3 to 16 years at the various stations. The smallest stations are omitted. The best stations covering more than half of the gas flow would have a pay-back time between 3 and 6 years. • The preliminary project proved successful and it was recommended to continue the pro-ject in a demo-project where a full scale expander system could be demonstrated. • Unfortunately it was not possible to find suitable demo-sites. The Danish gas companies did not want to invest in a demo-plant based on the above pay-back time, which they considered to be too long, and on uncertainty of feed-in tariffs for produced electricity. • Likewise it has not been possible to find foreign partners for a demo-site in the close vi-cinity of Denmark. • Future investments in the ZEGEX-concept imply a certainty of feed-in tariffs for pro-duced electricity and an economical appreciation of the saved CO2-emission of the concept.
