UPDATE 1-German court challenges power firms' nuclear expropriation claim

* 2011 law may have restricted ownership -vice president

* Decision to take several months, majority needed

* Court questions Vattenfall’s ability to lodge complaint (Adds details on panel, Vattenfall, shutdown chart)

KARLSRUHE, Germany, March 16 (Reuters) - Germany’s highest court on Wednesday challenged claims by power firms that a government decision to end nuclear power generation earlier than planned amounted to expropriation of their plants.

Following the Fukushima disaster in Japan in March 2011, Germany announced plans to exit nuclear energy by 2022, effectively speeding up a plan first drawn up in 2002 to eventually shut all of the country’s reactors.

Utilities argue that the move overturned a decision from late 2010, which backed extending the lifespan of some plants, and plan to claim damages for the production volumes they say they will be forced to forfeit.

They claim the accelerated shutdown robbed them of 1,800 terawatt hours of future production, enough to power Europe’s biggest economy for about three years.

The affected utilities, E.ON, RWE and Vattenfall, have all lodged constitutional complaints and could claim as much as 19 billion euros ($21 billion) should the court rule in their favour.

Ferdinand Kirchhof, vice president of Germany’s Constitutional Court, told the second day of a closely watched two-day hearing that the 2011 law may have restricted ownership, but not led to outright expropriation.

Kirchhof questioned whether it could be qualified as the withdrawal of property “if an instrument is being withdrawn at some point”, referring to the fact that Germany had merely accelerated the shutdown agreed upon in 2002.

Environment Minister Barbara Hendricks said that the additional production granted under the lifespan extension in 2010 was not legally protected.

A ruling will take several months and requires a majority of the eight-judge panel. If the judges are split evenly, the complaints will automatically be rejected.

EnBW, Germany’s third-largest utility, has not lodged a complaint as it is effectively owned by the public, which prevents it from doing so. The court therefore questioned Vattenfall’s ability to take such a step, since it is owned by the Swedish state. ($1 = 0.9020 euros)

Reporting by Ursula Knapp, Christoph Steitz and Tom Kaeckenhoff; Editing by Jason Neely and Keith Weir