Adding gas from biomass to the gas grid - SGC

Biogas is fed into the natural gas grid at two sites. One is a low pressure branch of the grid and thebiogas is therefore upgraded with PSA technology to meet the natural gas specifications. The othersite is at the high pressure transmission grid and here the biogas is added to the grid withoutupgrading. This is due to the very small percentage the biogas adds to the natural gas so there isno need for upgrading.Three biogas plants, utilising biomass, in Switzerland have filling stations for gas. There are noexplicit data available about the upgrading technique, but PSA seens to be the most commontechnology in Switzerland.A pilot project concerning biogas upgrading has been conducted. The project was divided into twostages. The stage 1 pilot plant was constructed at the biogas plant in Rümlang. The upgradingmethod was water scrubbing and the plant was started in 1993. The capacity was 12 m 3 /h. The gasquality was not as good as expected. The specifications could hardly be met. The energyconsumption for the upgrading process equalled one third of the gas energy in the upgradedmethane gas. In stage 2 a PSA plant was built at the Bachenbülach biogas plant in 1995 with acapacity of 26 m 3 /h. This plant had no problems in meeting the quality specifications and the energydemand for the upgrading process was only 8% of the heat value of the upgraded gas. Theinvestment cost for the PSA plant was almost one third lower than for the water scrubbing plant,even since the PSA plant had more than the double capacity.Filling stations in Switzerland are of two main types. Fast filling with compressor and high pressurestorage tanks for gas, and overnight filling equipment where the compressor is filling directly into thevehicle. These slow filling stations are sold for the use of one or only a few vehicles at a time andhave a trademark of ‘FuelMaker’. The number of fast filling stations is increasing at this moment.7.3 POLICY7.3.1 EuropeDirective on natural gasThe access of fuel gases to the European market is regulated in the 1998 EU directive ‘Commonrules for the internal market in natural gas’ [lit.33]. This directive sets the right of any producer to sellhis fuel gas to any client in Europe. This directive is limited to natural gas. Liquefied natural gas(LNG) and gases from natural gas storages are explicitly included in this directive. Gases frombiomass, organic waste, coal or oil are not explicitly mentioned.It is left to the Member States to impose public-service obligations to the natural gas undertakingsfor security, security of supply, regularity, quality, price of supplies and environmental protection.From this directive it may be expected that all gas from biomass that meets the requirements of anatural gas may be added to the grid.page: 95