Pinnacle West, parent company of Arizona Public Service, which owns this power plant in Tonopah, is the one suing.

PHOENIX — The parent company of the state’s largest electric utility filed suit Thursday in a bid to block voters from deciding if they want to impose new renewable energy mandates on power companies.

In a 48-page complaint, attorneys hired by Arizonans for Affordable Energy, funded by Pinnacle West Capital Corp., claim there are legal flaws in the initiative petitions submitted by Clean Energy for a Healthy Arizona.

The latter group’s ballot measure seeks to amend the Arizona Constitution to require 50 percent of electricity generated by most power companies in Arizona to come from renewable sources by 2030.

Initiative backers submitted more than 480,000 signatures. They need 225,963 to be found valid to get the issue on the November ballot.

But the lawsuit claims more than 195,000 of the names are from people not registered to vote in Arizona, and that nearly 75,000 signatures were submitted on petitions where there was a missing or improper notarization.

Other issues cited include signatures that do not match and petitions that were circulated before initiative backers got the proper registration number from the Secretary of State’s Office.

“There are a laundry list of issues,” said Matt Benson, spokesman for the utility-financed effort to quash the initiative. “But the point is, even all of those issues aside, obvious blatant deficiencies account for more than 300,000 signatures and push them well below the minimum threshold.”

The lawsuit, filed in Maricopa County Superior Court, seeks to disqualify signatures to show that there are not enough valid names left to put the issue to voters. But that’s not all: it asks Judge Daniel Kiley to void the entire petition drive, arguing that signers did not know what they were supporting.

For example, attorney Brett Johnson noted the measure is titled the “Clean Energy for a Healthy Arizona Amendment.” But Johnson pointed out that the mandate for 50 percent renewable energy by 2030 specifically excludes nuclear energy. He said that fails to acknowledge that nuclear energy generates about 20 percent of power in the United States with zero greenhouse gas emissions.

Pinnacle West’s wholly owned subsidiary Arizona Public Service is the major owner of the Palo Verde Nuclear Generating Station west of Phoenix.

Rodd McLeod, spokesman for the initiative, acknowledged that not every signature submitted ultimately will be found valid.

“The reason we handed in more than double the required amount is because we understand ... that you’re going to have a certain number of them that come up wrong,” he said. “There’s always going to be mistakes.”

“We are confident we have more valid signatures than the law requires and regard this lawsuit as foolish,” McLeod said. He called it “a desperate attempt to deny choice on what kind of energy we want to have in the future.”