It's the most wonderful time of the year, which means that New York's most iconic Christmas tree is lit, the rink at Rockefeller Center is busy and the Rockettes are performing. However, few realize the amount of energy that is required to keep building occupants and the tourists walking through the New York sites comfortable and happy. The amount of energy, especially at peak times, is expensive and negatively impacts our environment and electric grid. Can energy that is consumed during off peak periods and stored for later use help solve these problems and help to reduce the peak electricity demands, improve utility load factor and make renewables more viable even in the cold of winter?
The Real Magic
New York City is more than just a tourist destination, consisting of over 800,000 buildings. Although the above ground attractions get all the attention, the real magic happens in the basements and on the roofs, where ice-based thermal energy storage is in place at properties such as Rockefeller Center, Morgan Stanley and 11 Madison Avenue. On summer nights, when energy prices are nearly 70 percent discounted compared to daytime prices and energy is generated more efficiently, cooling is created and stored in the form of ice by a chiller. The next day the ice is melted to cool the building unbeknownst to occupants.
During the winter, when cooling loads are lower due to colder outside temperatures, the typical ice melt times for one iconic building is 15 hours. Ice can be used to meet cooling loads during the day with chillers only running at night. While many may not think to cool buildings in winter, large buildings require some cooling due to heat emitted from people, lighting and computers. During the summer, ice is burned for six hours (usually 12 noon to 6 p.m.) throughout peak demand times, thus reducing energy consumption when the grid is most vulnerable and reaching capacity. This strategic use of energy storage is benefitting the power grid, the building and the city.
Even though buildings have been using energy storage for decades, the value of this technology is just starting to be recognized, especially in New York City. Across the United States, nuclear and coal power plants may be shut down in the coming years. This would remove massive amounts of power generation from the grid. However, with enough energy storage implemented into the grid, it is possible to meet electricity demand without the plants. Energy storage used to its fullest potential could mitigate that impact.
Peak Demand and When We Use Power
The time at which energy is used is just as important as how much is used. Peak demand for electricity has shaped the way our power grid works and the infrastructure that has been put in place. The power grid has been structured to be big enough to meet the few hottest or coldest hours during the day when energy consumption is at its highest, mostly due to heating and cooling operations. Summer brownouts and blackouts are a common result of these dangerous peaks that are pushing the power grid beyond its limit. Sizing the power grid to these few times of extreme demand has left it bigger and less efficient during the rest of the year. The nation's utility load factor is further proof of this.
The utility load factor of the United States is right around 50 percent. This means on average we are only using 50 percent of the utility infrastructure that is in place. The lower this percentage, the less efficient the power grid is and the higher the number the more efficient. This figure has been on a steady decline since the 60's when the load factor was north of 65 percent. With a 50 percent load factor, we have twice as much generation as we actually need if we were able to produce energy at a steady rate day and night. The more consumption we can shift to off-peak hours, the better our grid will perform. This is how New York City would be able to shut down an entire power plant by implementing energy storage.
Encouraging the Use of Renewables
It's no secret across the United States, especially in New York City, that energy is at a premium and that renewables can potentially ease the financial burden. Energy storage is a vital component to renewables, since unlike coal, solar and wind are pure energy with no storage capabilities. Energy storage allows a consumer to use the energy when they want, instead of trying to match supply with demand as it happens.
The biggest problem with renewables, however, is the intermittency issue that arises with wind and solar energy. Weather conditions affect the amount of energy that is being generated from renewables. Without storage, the renewable energy can't always be used to its fullest potential. To help solve this problem, energy storage can kick in when the wind is not blowing or the clouds roll in. The energy from wind is best captured at night when wind is most active and demand is already low. With storage, wind energy may then be put to use during peak demand hours. In dense urban environments it is difficult to collect renewables, however those dense urban locations are the best places to store the energy. Installing energy storage, in all its forms, at the source of consumption makes sense, whether it is in the basement of a building or on the roof. Renewables should be placed outside the City instead.
Big Picture
All types of energy storage will be needed to create a more sustainable future. Right now, the power grid is the biggest mechanical system in the world with almost no storage capability. Buildings, like offices, schools and hospitals, that are implementing energy storage are helping to achieve large-scale results. Imagine being able to shut down half of the nation's power grids or implementing more renewable energy into our society. Each building is a stepping stone to a future where this is a reality.