Biogas Upgrading Comes to Small-Scale Farms
Posted by Lee Drever on Tue, Aug 30, 2011
The anaerobic digestion process solves two big problems by creating energy from waste. The simplest way for a small-scale agricultural operation to do this has been to use the biogas derived from the digester to fuel a generator, pumping electricity onto the farm and surplus energy back on to the grid.
Large-scale operations have also had the option to invest in upgrading equipment and sell to utilities companies like Fortis in British Columbia. In its raw form, biogas contains other gases not compatible with natural gas. Upgraded or "scrubbed" however, it becomes biomethane or renewable natural gas. This process has been cost-prohibitive for a small-scale operation but a company in Sweden is hoping that their upgrading technology will fill that niche.
Artic Nova has developed a small-scale upgrading system called BioSling, making it possible for farmers to turn their waste into fuel for their (and even their neighbour's) vehicles. Suitable for operations with as few as 200 cows, BioSling is a flexible alternative to simple electricity generation.
Coils of plastic hoses constitute the main component of BioSling. The vessel shown in the background accumulates the upgraded gas and separates it from water saturated by carbon dioxide.
The system is contained in a standard 24ft container consisting of a control room and an upgrading room. Rotating coils of plastic hosing force the raw biogas in contact with water, effectively scrubbing the gas of impurities and carbon dioxide increasing the methane content to 94 per cent. Biogas of this purity is ideal for for farm equipment and converted spark ignition or diesel engines.
Further scrubbing is possible (and required) to send natural gas to the grid but excess is easily stored in pressurized cylinders.
Is it expensive? Sure, but if renewable energies are to become a real alternative, investment will is required. Many European countries are already leading the way with subsidies for green technologies. As energy prices increase in North America, the will to do the same is starting to appear and consumers do seem eager to support renewable energies.
Is anaerobic digestion right for your operation?
