* New turbine additions reach annual record in 2014

* Installations in 2015 seen at 3,500-4,000 MW

* Installed total rises 13 percent

FRANKFURT, Jan 29 (Reuters) - Germany’s newly installed onshore wind power capacity rose by a record 4,750 megawatts (MW) in 2014, industry groups said on Thursday, marking what is likely to be a peak annual gain as the country gears up for a nuclear-free future.

Representing additional energy production roughly equivalent to one nuclear plant, the increase was 58 percent bigger than in 2013.

Reckoning with new land resources made available following Japan’s Fukushima nuclear disaster in 2011, engineering group VDMA and wind energy association BWE said new capacity may range between 3,500 and 4,000 MW in 2015 before a likely decline in 2016.

“Onshore wind in 2014 made another big leap ahead and underscored its role as the engine of (Germany’s energy transformation),” said BWE president Hermann Albers.

The country is moving away from using fossil fuels and relying increasingly on renewable energy as part of a programme to completely phase out nuclear power by 2022.

The 2014 additions were on a gross basis. If 364 MW that were dismantled are deducted, the net addition was 4,386 MW - still well ahead of the previous record gain of 3,240 MW in 2002 and roughly equivalent to four nuclear power plants.

However, the comparison is not like-for-like: renewable capacity can only run at around a quarter to a third of the time on average while conventional thermal capacity can produce power without interruption.

The new installed total at the end of December was 38,116 MW, up 13 percent. The new volume included 1,148 MW of repowering, or replacing turbines at existing sites.

Germany’s long-running green energy drive, which originated in a wish to pursue climate targets and become more independent of energy imports, picked up speed after Fukushima highlighted nuclear technology risks.

The latest figures show the boom continues unabated, despite legislative changes last August that capped renewable subsidies and accelerated the timetable for green operators to join the wholesale power market.

Renewable energy accounted for 25.8 percent of the country’s power production mix in 2014 and is set to grow to 40-45 percent by 2025 and to 80 percent by 2050.

Though still tiny by comparison, Germany’s offshore wind capacity more than doubled by last year to 2,350 MW, VDMA data showed earlier this month. (Reporting by Vera Eckert; editing by John Stonestreet)