OFM: Biogas Application

Biogas is produced by digestion of organic materials in farming, waste water and garbage processing facilities. Having less that a half of energy provided by natural gas (due to high moisture and CO2 content), biogas nevertheless is a very important factor in current global warming and environmental problems. First, as a strong contributor to green house effect due to high content of methane. Second, as a free source of energy.

Collection and utilization of biogas requires its measurement which become challenging for traditional flow metering techniques. Independently where biogas is produced, its chemical composition is changed with weather (temperature, humidity) and time. Compact and cost-efficient thermal mass flow meters cannot be applied for biogas measurement unless they are calibrated for various mixtures of water vapor, methane and CO2 and biogas content is constantly measured. Also, biogas builds up under low pressure which insufficient for normal operation of differential gas flow meters. Turbines meters are not suitable for biogas which interferes with blades and bearings. Ultrasonic gas flow meters remained solely as meters of choice for biogas, however, their application was limited because of high cost frequently comparable with cost of the whole biogas producing facility.

Biogas expected the appearance of optical gas flow meters (OFM) as they are ideal for this tough application. OFM measure gas flow independently on gas composition and under any possible low pressure. Biogas always includes water droplets and other particulates which modulate laser beams – an essential feature for “laser-two-beam” technology. Installations at local facilities operated by Greater Vancouver Regional District proved that.