Utilities

Electricity and gas supply

As a significant proportion of the world’s coal fired power generation has been replaced with natural gas power stations and combined heat and power units, the management of high-pressure methane supplies is of crucial importance to avoid risks of explosion. Flammable gases also pose hazards in smaller scale renewable power schemes based on aerobic digestion of waste material to generate biomethane. For those power stations that remain coal-fired or have been converted to the use of biomass such as wood pellets, the hazards of potential dust-based explosive atmospheres must be managed for safety.

Hydrogen cooling

For larger power station generator sets (typically those of 60MW capacity and above) hydrogen is used as a cooling agent rather than air. Hydrogen is attractive for this application due to its high thermal conductivity and low density, which offers greater efficiency of energy conversion. Within the generators, the hydrogen is maintained at a concentration well above the upper explosive limit. However, significant risks remain in terms of the safe management of hydrogen on site, not least in being prepared for potential leaks.

Water treatment

Methanol dosing of wastewater discharged from treatment facilities is widely used by the water industry. Its addition acts as a supplemental carbon source for denitrification and is used in particular where treatment works outfalls contain high levels of nitrogen and phosphorous, or where the works is in an environmentally sensitive river catchment or estuary. A highly flammable liquid, methanol combusts with a flame that is almost invisible in daylight conditions, meaning that its safe handling and management is crucial for safety.

The downstream processing of sewage sludges can also present explosive risks. In addition to the use of sludge in anaerobic digestion to yield biomethane, its drying for the manufacture of fuel pellets can also present risks in terms of dust explosion.