the main lines were refurbished after 1990, resulting in improved speed of travel. The most important railway lines at present are the Thuringian Railway, connecting Halle and Leipzig via Weimar, Erfurt, Gotha and Eisenach with Frankfurt and Kassel and the Saal Railway from Halle/Leipzig via Jena and Saalfeld to Nuremberg. The former has an hourly ICE/IC service from Dresden to Frankfurt while the latter is served hourly by ICE trains from Berlin to Munich. In 2017, a new high speed line will be opened, diverting long-distance services from these mid-19th century lines. Both ICE routes will then use the Erfurt–Leipzig/Halle high-speed railway, and the Berlin-Munich route will continue via the Nuremberg–Erfurt high-speed railway. Only the segment west of Erfurt of the Frankfurt-Dresden line will continue to be used by ICE trains after 2017, with an increased line speed of 200 km/h (currently 160 km/h). Erfurt's central station, which was completely rebuilt for this purpose in the 2000s (decade), will be the new connection between both ICE lines. The most important regional railway lines in Thuringia are the Neudietendorf–Ritschenhausen railway from Erfurt to Würzburg and Meiningen, the Weimar–Gera railway from Erfurt to Chemnitz, the Sangerhausen–Erfurt railway from Erfurt to Magdeburg, the Gotha–Leinefelde railway from Erfurt to Göttingen, the Halle–Kassel railway from Halle via Nordhausen to Kassel and the Leipzig–Hof railway from Leipzig via Altenburg to Zwickau and Hof. Most regional and local lines have hourly service, but some run only every other hour. A few small airports are in Thuringia. In public transport is Erfurt–Weimar Airport, used for charter flights to the Mediterranean and other holiday destinations. In private flights, Leipzig–Altenburg Airport is a further key airport. International hub airports are Frankfurt Airport, Berlin Brandenburg Airport and Munich Airport in adjacent states. Thuringia is the only state without barge or ship waterways; its rivers are too small to be navigable to them. Energy and water supply The traditional energy supply of Thuringia is lignite, mined in the bordering Leipzig region. Since 2000, the importance of environmentally unfriendly lignite combustion has declined in favour of renewable energies, which reached an amount of 40% (in 2013), and more clean gas combustion, often carried out as Cogeneration in the municipal power stations. The most important forms of renewable energies are Wind power and Biomass, followed by Solar energy and Hydroelectricity. Furthermore, Thuringia hosts two big pumped storage stations: the Goldisthal Pumped Storage Station and