Biogas forming in sewers via anaerobic digestion can be a potentially smelly and explosive hazard (chiefly due to methane). Unlike ordinary gas lamps for street lighting, the main purpose of sewer gas destructor lamps is to remove sewer gases and their hazards. Joseph Edmund Webb of Birmingham patented a sewer gas destructor lamp.
Many of these lamps were installed in the UK in towns and cities such as Sheffield, Winchester and Blyth, Northumberland. With a flame generated by burning town gas, sewer gases were drawn from the sewer below and burnt off along with the town gas to produce mainly carbon dioxide.
It has also been found that when the gases are drawn out from the sewer by the burning of ordinary gas a sudden flushing of the sewer might prevent any sewer gas from escaping, and thus momentarily cause the gas jets to be extinguished.
In order to solve this problem the patent specifies an arrangement of burners, air supply and heat reflection designed to produce an intense heat at the point of combustion. (Webb suggests 600 to 800 degrees Fahrenheit).
The lamps were installed at places where sewer gases were likely to collect, such as at the tops of hills. The city of Sheffield, being a hilly area, had many sewer gas destructor lamps and many remain.
Sheffield on the Net has a section on the old gas lamps, which states:
Eighty-four of these street lamps were erected in Sheffield between 1914 and 1935, the largest number in any British town, due mainly to the many hills in the area where gas could be trapped.
The Sheffield Star newspaper reported a local survey of the lamps by W Jessop. This survey found 22 remaining lamps in Sheffield.
Although many of the existing lamps in Sheffield and elsewhere are now disused, the lamps still have a use today in reducing the hazards of explosion and also perhaps in reducing the greenhouse effect by stopping methane escaping into the atmosphere. The sewer gas destructor lamps convert methane (a potent greenhouse gas) from the sewers into carbon dioxide (a lesser greenhouse gas).