How did Morbi tile kiln fuels change from kerosene to coal gas to piped gas, and what records should a unit keep if it switched part way through a year?

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The Morbi manual says the cluster began on kerosene in the early 1990s, moved to liquefied petroleum gas in the mid 1990s, then after 2000 to coal gas from gasifiers, and later to piped natural gas for kilns. If you switched mid-year, count each month's fuel with its own factor. Early 1990s: kerosene as the thermal fuel. Mid 1990s: liquefied petroleum gas (LPG). After 2000: producer gas, which is a fuel gas made by burning solid fuel, such as coal or lignite, with too little air in a machine called a gasifier. It replaced LPG because LPG's energy cost more than energy from coal gas. In the years before the manual (2010): piped natural gas arrived, and many units moved their kilns onto it. Gasifiers, and a machine the manual calls a potrifier that burns coal in a bed of hot air-blown particles to give hot gas, stayed the main source for spray dryers. With time and quality problems, some units moved spray dryers to natural gas too. Those that did were considering making their own power with the exhaust heat as well. Natural gas came from the Gujarat State Petroleum Corporation (GSPC), with a good network in Morbi. The Gujarat Mineral Development Corporation gives units a monthly quota for buying coal. Weekly electricity load shedding was usual, and most units have their own diesel generator sets for the gaps. It also names biomass, briquettes, sawdust and wood as thermal fuels used in some units. Each fuel has its own carbon dioxide for each unit you buy. If a unit ran its kiln on coal gas for five months and piped gas for seven, a single average factor for the year would be wrong for both halves. Count each month with the factor for the fuel burnt that month, then add the months. The month of the switch and what changed: kiln, spray dryer or both. Coal purchase invoices and any quota letter, with tonnes and the supplier's heat value if printed. Quota papers show an allowed tonnage, not what you burnt, so count from invoices and stock. Gas bills with the meter reading for the kiln and, if separate, the spray dryer. Diesel bought for the generator set. Outages make this a regular fuel, and it is easy to forget.

How did Morbi tile kiln fuels change from kerosene to coal gas to piped gas, and what records should a unit keep if it switched part way through a year?

The sequence the manual gives

What else the manual says about supply

Why a mid-year switch is tricky

Records to keep

A year with a switch in July, example numbers

What Senseible does here