* Transmission upgrades, costing $500 million, recommended
* Approval needed by April to be ready in 2016-filing
HOUSTON, Feb 1 (Reuters) - A combination of transmission, generation and energy conservation measures will be needed to maintain electric service in New York City if the Indian Point nuclear plant is forced to close, Consolidated Edison Inc said in a regulatory filing made on Friday.
New York Governor Andrew Cuomo wants to shut the two reactors at Indian Point when their operating licenses expire in 2013 and 2015 because of the plant's proximity to the New York metro area, home to some 19 million people.
The 2,063-MW Indian Point station, located 40 miles (60 km) north of Manhattan, supplies about a quarter of the Big Apple's electric supply.
Con Edison has warned that early retirement of the nuclear facility "without sufficient alternatives, would threaten electric reliability and potentially raise electric market prices" in New York City.
After Hurricane Sandy left millions of New Yorkers without power last year, the New York Public Service Commission (PSC) called on Con Edison and state-owned New York Power Authority (NYPA) to develop contingency plans in case the Indian Point reactors shut when the units' licenses expire.
On Friday, Con Edison and NYPA proposed a package of three transmission upgrades costing more than $500 million, which they said need regulatory approval as soon as April to move forward so they can meet the city's power needs by mid-2016.
"The plan consists of several integrated components, all of which need to be timely approved so that they can move forward according to the schedule," Con Edison said in the filing.
In addition, the companies asked regulators to act as early as March on a separate plan to solicit additional generation and transmission projects that can be in operation by the 2016 deadline.
Con Edison also wants to expand its demand-response program by 100 megawatts to curb power use when the power grid is strained.
The transmission projects that Con Edison said are needed include a 345-kilovolt transmission line costing $123 million; projects to relieve grid congestion on Staten Island costing $311 million; and replacement of transmission conductors costing $76 million.
Friday's filing gave few specifics on the amount of new generation that might be needed in the proposed solicitation.
Executives with NRG Energy said this week that their efforts to modernize several power plants could bolster the New York power supply in the event the Indian Point reactors are retired.
New Orleans-based Entergy Corp, which owns Indian Point, maintains the plant is safe and is seeking to extend the reactors' federal operating licenses for another 20 years.