UPDATE 2-Obama approves nuclear energy deal with UAE

* Next step in approval process is sending it to Congress

* If approved, deal could generate $40 billion of business

* Supporters say lawmakers' concerns can be addressed (Updates with more detail)

By Doug Palmer

WASHINGTON, May 20 (Reuters) - U.S. President Barack Obama on Wednesday approved a nuclear energy deal with the United Arab Emirates worth potentially billions of dollars to U.S. energy companies, setting the stage for Congress to decide whether to block it.

"I have determined that the performance of the agreement will promote, and will not constitute an unreasonable risk to, the common defense and security," Obama said in a statement that made no reference to U.S. concerns over a video showing a member of the ruling of family of Abu Dhabi allegedly abusing a man who is beaten with a plank of wood with a nail on it.

The administration of former President George W. Bush signed the pact with the wealthy Gulf state just days before leaving office in January.

The political climate for Obama to approve the pact became more difficult after a gruesome video surfaced showing an Afghan man being abused with an electric cattle prod, beaten with whips and a plank of wood with a nail on it and driven over by a car at a desert location in 2004.

Abu Dhabi's judicial department earlier this month said prosecutors had detained Sheikh Issa bin Zayed al-Nahyan, a brother of the UAE crown prince, pending an outcome of an investigation into the video.