Several electric commuter suburban railway lines operate in eastern New Jersey and serve Newark, Hoboken and extend to New York's Penn station. Amtrack also operates electric intercity passenger trains into and from New York. During weekday peak periods, the New York subway trains can consume up to 500MW of electric power and there are plans to build new subway lines at greater depths. Future plans may include converting some of the diesel-powered commuter railway services in New York and New Jersey to electric power. The 3 airports (JFK, La Guardia and Newark) also consume substantial amounts of electric power during the peak periods.
Within the next 20 years, it is possible that transportation services may consume up to 1GW of electric power during peak periods, or the output of the US-side of the Moses-Saunders power dam near Massena NY. The amount of future power that transportation services will require in and around New York City opens the door to examine the prospect of storing transportation electric power in close proximity to the transportation services. Despite the efficiency loss incurred in operating grid-scale energy storage systems, the prospect of gaining access to low cost off-peak power may enhance the feasibility of developing such a system.
New York State shares a border with Ontario, Canada, where a news story broke as to how Ontario has for several years, sold off-peak electric power to outside utilities. Instead of the outside utility paying Ontario for excess off-peak generating capacity, Ontario has actually paid outside utilities to take delivery off that off-peak capacity. Ontario is one of several power utilities that operate nuclear power plants that operate at constant output and pay outside utilities to take delivery of excess off-peak generating capacity. Officials at Massena NY have expressed support to having a future nuclear power plant being built in their district and in close proximity to the Moses-Saunders international hydro dam on the St Lawrence River. As well, Hydro Quebec usually has excess off-peak generating capacity available during the summer months.
The ability to store electric power in close proximity to the mass transportation systems in and around New York City would make more efficient use of the electrical transmission system. That system could carry massive amounts of electrical energy to the New York City area during the overnight period, to be transferred into future local energy storage. During peak periods, that storage could allow electrically powered mass transportation system and the airports to operate "off-grid" and to continue to operate in the event of a system malfunction or power blackout on the grid. The ice storm of 1998 shut down electric power across much of New England for several days, while other power blackouts have previously shut down the New York Subway system.
The New York Power Authority had recently explored the potential to increase pumped hydraulic energy storage in the Catskill Mountains area, except that opposition from environmentalists shelved the plan. Much of NYC bedrock is hard, impervious rock and ideal for pumped underground hydraulic storage. Environmentalists would probably allow for the excavation of large caverns some 2000-ft below maritime sea level in the NYC bedrock, for the purpose of pumped underground hydraulic storage using ocean water. The turbines and related equipment would need to be corrosion-resistant.
While salt caverns occur across Northern New York State near the St Lawrence River, it is as yet unknown as to whether such a cavern or salt deposit may exist deep under the bedrock of NYC or surrounding districts. The existence of an appropriate size and shape of underground salt deposit may otherwise serve as a basis for compressed air energy storage (CAES) that may include a seawater displacement option to increase storage capacity.
The mass transportation systems in around New York City will likely expand and consume more electric power in the future, including as electric propulsion replaces diesel propulsion on some suburban commuter services. An energy storage system built in or near NYC would likely have access to future low-cost off-peak electric power and free up peak-hour capacity on the transmission lines that carry electric power into the city. While electric powered road vehicles may enter service in NYC, the market penetration may still result in available off-peak power that could be placed into storage, for passenger mass transportation applications.