METHANE AND THE FOUR ALCHEMICAL ELEMENTS IN OUR ENVIRONMENT
Anaerobic sewage sludge digesters
Water, earth, wind and fi re were regarded by the alchemists as the four classical elements making up our natural environment; methane has a place in each of these. In waste water treatment anaerobic sludge digesters convert biomass to methane, which can be fi red in a gas engine to produce electrical power. In landfi ll sites and natural soils, methanogenic bacteria convert biomass to methane which is released to the air and carried by the wind throughout the troposphere where it is a potent greenhouse gas. Deep in the earth, methane is trapped in coal and rock seams. If this fl ammable gas accumulates during mining activities, it can create explosive fi re balls and gas detection is used to mitigate this risk. So, the monitoring and detection of methane gas is important for safety or environmental management in all four of these alchemical elements.
From an environmental management perspective, carbon dioxide (CO2
) emissions are the main source of global warming gas
emissions from the transportation sector and industry. On the other hand, small quantities of methane emissions also contribute to global warming because methane has a global warming potential (GWP) 28 times higher than CO2
. Transportation
methane emissions are regarded as diffuse sources of pollution. On the other hand, emissions from power plants, offshore gas rigs, power plants, water treatment facilities and landfi ll sites are categorised at facility level and methane emissions data for many sites is reported in the European Pollutant Release and Transfer Register (E-PRTR).
Measuring transport methane emissions and water. This is especially
Methane is produced in car, bus and truck engines when fuel is not completely burned to form CO2
the case during cold-starts, when the ratio of fuel and air in the engine is adjusted by ‘choking’ the air supply to increase the relative amount of fuel. The change in the reaction stoichiometry causes incomplete combustion of the fuel and slip of hydrocarbons through the engine. Vehicles that run on compressed natural gas (CNG) also have a higher methane emission footprint than vehicles with petrol and diesel engines.
To ensure that methane and other hydrocarbon emissions from transportation are minimised, the development of effi cient modern engines and power trains relies on many thousands of hours of engine testing. These tests and the related methane emissions
Power plant stack emissions
crackers. The USA is now a major hydrocarbon exporting nation in the form of liquefi ed natural gas (LNG) exports from the Gulf Coast.
Water, Earth, Wind & Fire - alchemical elements
limits are governed in Europe by the Euro 6 automotive emissions regulations and in the US through the 49 CFR Regulations for Greenhouse Gas Emissions from Passenger cars and Trucks. The exhaust gas composition is measured under a range of simulated driving conditions from low speeds to high load conditions. A suite of gas analysers is used to measure particles, hydrocarbons, oxides of nitrogen and other pollutant gases in the exhaust. For the detection of hydrocarbons, a fl ame ionisation detector (FID) is used. In order to differentiate methane from other heavier hydrocarbons, cryogenic traps and molecular sieves can be used with gas chromatography prior to the FID detector. High purity specialty gases and traceable calibration gas mixture cylinders are required to ensure that the gas analysers in these engine testing facilities operate effectively and are calibrated according to the regulations.
The shale gas revolution
In the United States, shale gas has revolutionised the economy and the implications ripple worldwide through the export of products such as ethane shipments to European and Asian Ethylene
Deep shaft mining for coal and gold IET ANNUAL BUYERS’ GUIDE 2020/21
WWW.ENVIROTECH-ONLINE.COM Shale gas drilling in the USA
Safety at gas terminals, processing stations and LNG storage facilities is often enhanced using open path methane gas detectors. They use infrared light to detect fl ammable gases that are infrared active, such as methane. These gas detection devices differentiate from each other in the way they compensate for the potential interactions from fog and rain and their resistance to solar interference. Most units have a very rapid response time, reacting within a few seconds and when suitably specifi ed, are generally able to scan across a path of up to 100 metres, so a
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