Shale oil
Shale oil production started in Estonia in 1921 when Riigi Põlevkivitööstus built 14 experimental oil shale processing retorts in Kohtla-Järve. These vertical retorts used the method developed by Julius Pintsch AG that would later evolve into the current Kiviter processing technology. Along with the shale oil extraction plant, an oil shale research laboratory was founded in 1921. Following the experimental retorts, the first commercial shale oil plant was put into operation on 24 December 1924. The German-owned company Eesti Kiviõli (, , predecessor of Kiviõli Keemiatööstus), affiliated with G. Scheel &amp; Co. and Mendelssohn &amp; Co., was established in 1922. By the end of the 1930s, it had become the largest shale oil producer in Estonia. Around the company's mine and oil plant, the Kiviõli settlement (now town) was formed in the same way as the Küttejõu settlement (now district of Kiviõli) formed around the mine owned by Eesti Küttejõud. In 1924, the British investor-owned Estonian Oil Development Syndicate Ltd. (later Vanamõisa Oilfields Ltd.) purchased an open-pit mine in Vanamõisa and opened a shale oil extraction plant that was abandoned in 1931 due to technical problems. The Swedish–Norwegian consortium Eestimaa Õlikonsortsium (, ), controlled by Marcus Wallenberg, was founded in Sillamäe in 1926. New Consolidated Gold Fields Ltd. of the United Kingdom built a shale oil extraction plant at Kohtla-Nõmme in 1931. This facility continued to operate until 1961.