"Verein der Kohlenimporteure (VDKi) expects significant volumes increases in the monthly import figures from September onwards," Alexander Bethe, the chairman of the German coal importers' group, said in reply to an enquiry by Reuters.

September could bring a 50 percent rise over May, Bethe said, when imports had been 2.35 million tonnes. Monthly coal receipts recorded last winter by VDKi members ran at 3.5-4 million tonnes.

Australia, South Africa, Indonesia and Colombia were all cited as potential coal suppliers by the VDKi earlier this year.

Bethe said the need for fossil fuels also depended on weather patterns and their impact on electricity output from wind turbines.

Issues with logistics include a lack of handling capacities at sea ports and on board inland river barges, which can only sail with reduced loads as hot and dry weather has cut river levels, as well as tighter availability of rail freight space.

The most important Kaub river choke point on the Rhine, through which ships to the industrial areas of Mannheim and Karlsruhe have to pass, is at only 52 cm WL-KAUB, while barges need about 1.5 metres of waterline to sail fully loaded.

Bethe said however that there were some positive prospects going forward, including the reversal of a temporary move by some river barges to Romania to support Ukrainian grain exports.

Low water conditions on rivers and canals might prevail until the middle or end of August, but could then ease, freeing up more shipping space.

Germany may import 32 million tonnes or more of steam coal for power this year, up from 27 million tonnes last year, Bethe estimated, again citing the availability of wind power and weather-driven demand. 

These volumes constitute two-thirds of coal imports, with the remainder going to steelmakers in the form of coking coal.