Research on the solid heat carrier process for pyrolysis of lignite, peat, and oil shale started in 1944 at the G. M. Krzhizhanovsky Power Engineering Institute of the Academy of Sciences of the USSR.

A pilot unit with a capacity of 2.5 tonnes of oil shale per day was built in Tallinn in 1947.

[1][4] The first Galoter-type commercial scale pilot retorts were built at Kiviõli, Estonia, in 1953 and 1963 (closed in 1963 and 1981, respectively), with capacities of 200 and 500 tonnes of oil shale per day, respectively.

It was used for testing Lviv–Volinsk lignite, and Carpathian, Kashpir (Russia), and Rotem (Israel) oil shales.

[1] In 2008, Estonian energy company Eesti Energia, an operator of Galoter retorts at the Narva Oil Plant, established a joint venture with the Finnish technology company Outotec called Enefit Outotec Technology to develop and commercialize a modified Galoter process–the Enefit process–which combines the current process with circulating fluidized bed technologies.

[9][10] In 2012, Eesti Energia opened a new generation Galoter-type plant in Narva using Enefit 280 technology.

[17][18] Before retorting, the oil shale is crushed into fine particles with a size of less than 25 millimetres (1.0 in) in diameter.

When the heat transfers from the hot ash to raw oil shale particles, the pyrolysis (chemical decomposition) begins in oxygen deficit conditions.

[5][16] Spent shale (semi-coke) is transported then to the separate furnace for combustion to produce hot ash.

A portion of the hot ash is separated from the furnace gas by cyclones and recycled to the rotary kiln for pyrolysis.

Compared to the traditional Galoter, the Enefit process allows complete combustion of carbonaceous residue, improved energy efficiency by maximum utilization of waste heat, and less water use for quenching.

[11] In addition, Eesti Energia planned to begin construction of similar Enefit plants in Jordan[26] and in USA.