SNG: a new biomass-based energy carrier

Although biomass is considered one of the pillars of alternative energy sources, it mostly cannot be used as such and should be converted to another type of energy carrier. One attractive option is Substitute Natural Gas: SNG. It re sembles natural gas and can be treated as such. This means that it can be stored and transported easily and can be applied without practical and environmental problems at any scale. Furthermore, the market introduction of SNG can take place gradually, similar to the introduction of green electricity in the past. It is therefore expected to have a high social acceptance. SNG can be used as a renewable fuel to drive cars, to generate heat on any scale, or any other application that is common for natural gas. The production of SNG from biomass involves gasification, gas cleaning, methanation, and gas upgrading as shown in the schematic picture below. In order to produce SNG from biomass that can survive as an energy source, it should be produced as cheap as p ossible. Since biomass generally is not cheap, a high efficient biomass-to-SNG system is a prerequisite. ECN therefore started the development of a biomass gasification technology that enables 70% overall efficiency from biomass to SNG. This so-called MILENA technology is capable of producing very high amounts of "instant SNG" (mainly methane), thus minimizing the need for methanation in which H2 and CO are converted to methane and 20% heat. Since 2004, ECN operates a 5 kg/h lab- scale test unit and an exten sive research programme started on SNG production, including gas cleaning, methanation and gas upgrading.