Energy storage is the perfect technology to complement renewable energy generation. Utility-scale solar arrays and wind turbines can now deliver electricity at a lower cost than power plants fired by fossil fuels, as evidenced by recent contracts signed in Mexico and the Middle East, with wholesale energy prices going below 2 cents per kilowatt-hour. However, these renewable energy systems are still limited by their variable energy production, depending on inputs that mankind cannot control - wind and sunshine.

Local authorities have seen the potential of energy storage, and a bill has been signed to establish a statewide capacity target. The exact value will be determined in early 2018, after authorities carry out the necessary analysis to set a realistic target. Only three other states had established energy storage targets before New York: California, Oregon and Massachusetts. New York City in particular has already established a citywide energy storage target: 100 megawatt-hours by 2020, and 1,000 MWh by 2030.

Utility-Scale Energy Storage: Brief Overview

There are many viable ways to store energy for a power grid. The most common method in the world is currently pumped-storage hydroelectricity (PSH), where generators and turbines are designed to reverse their operation and work as motors and pumps. Energy from the grid is used to pump water into the reservoir when there is excessive supply, while that same water is used to generate electricity during demand peaks. You may be wondering how this is viable with the round-trip energy losses, but electricity is far more expensive to generate during peak demand hours - from the financial standpoint, losing some low-cost electricity to store a large amount is better than generating expensive electricity when needed.

Unfortunately, PSH is very demanding in terms of site conditions, becoming extremely expensive when there is no adequate site. Therefore, lithium-ion batteries are emerging as a promising alternative: they can adapt to any site and have a modular design that is scalable for any project size. The only drawback of lithium batteries is their high cost, although they are becoming more affordable each year. Their price has dropped to the point where they are viable in places with expensive electricity, such as California, Australia and island countries.

New York City currently faces many challenges that could be solved with widespread adoption of lithium-ion batteries, but there is one hurdle to overcome. Fire protection requirements in NYC are among the most demanding in the world, and regulations for lithium-ion batteries have not been developed yet. This article will provide an overview of some NYC challenges that lithium-ion batteries can solve.

1) Meeting the NY State Renewable Energy Target

By 2030, the state of New York aims to generate 50% of its electricity from renewable sources. This is beneficial for the environment and for society, but comes with a technical issue. Rely too much on solar power and you will have power supply issues during nighttime and cloudy days, and with excessive wind power you will have the same problems when the weather is too calm.

Power plants that run with fossil fuels are highly polluting, but we must give them credit: they can always be counted on to supply power if their respective fuel is available. Solar and wind power only deliver this performance if complemented with energy storage - when sunlight or wind are not available, previously stored energy is used to achieve a stable output.

New York is a promising market for solar power; while considerably less sunny than California, the state of New York also has expensive electricity, and photovoltaic systems are now cheaper than when the solar power boom took place in California. With systems that combine solar power and lithium-ion batteries, New York could go a long way towards the statewide renewable energy target.

2) Reducing Greenhouse Gas Emissions in NYC

As we have mentioned in previous articles, NYC has a very demanding emissions reduction target: 80% by 2050, taking 2005 as a baseline. Unfortunately, NYC is still very dependant on natural gas for electric power and heating, and also depends to a lesser degree on heating oil. City authorities are addressing the oil problem - buildings that still use #4 heating oil must switch to cleaner fuels by 2030.

However, phasing out natural gas is much more difficult, since NYC relies strongly on it for power generation. Replacing gas-fired power plants with conventional solar panels and wind turbines is unfeasible for the reasons mentioned in the previous section, but it can be done if these renewable generation systems are equipped with large-scale battery arrays.

Although natural gas produces less GHG emissions per megawatt-hour of electricity, compared with other fossil fuels like coal and fuel oil, it produces emissions nevertheless. On the other hand, a system that combines renewable generation and battery storage is emissions-free during operation.

3) Preventing Upcoming Power Supply Issues

The natural gas power plants that supply NYC with electricity during peak demand hours are approaching the end of their service life, and many of them will be decommissioned during the next decade. The easy solution is to install new ones with superior efficiency, but this hinders two goals: the statewide clean energy target and the NYC emissions reduction target. Large-scale adoption of energy storage can make the power supply more reliable while contributing towards these two goals.

Also consider that solar power and lithium-ion batteries are flexible in terms of system capacity and safe to install in residential and commercial buildings; the same cannot be said of gas-fired power plants, even if we use the most modern designs and equipment available. Utility-scale energy storage systems running with lithium-ion batteries can also be brought online very quickly, as evidenced by recent projects in California and Australia. This gives authorities more breathing room to manage the decommissioning of aged power plants fired by natural gas.

According to the New York Independent System Operator (NYISO), over 2,200 megawatts of new capacity will be required in the state by 2026 to cover the gap left by decommissioned gas and nuclear power plants.

4) Avoiding Expensive Power Grid Upgrades

An advantage of renewable generation systems and lithium-ion batteries is that they can be installed at client premises, which decongests load on the power network. The NYC population can be expected to continue growing, and so will demand for electricity. The use of distributed energy resources will delay expensive power grid upgrades, which translates into stable power transmission fees - a significant portion of the power bill you pay.

Keep in mind that NYC is basically an island and space is limited. One option is to upgrade the power lines leading to the city, while another is to simply use the available rooftop area for solar generation, complemented with lithium-ion battery arrays across multiple buildings.