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Introducing "Shave the Peak": A New Way to Green the Grid

Shave the peak web header

At Green Energy Consumers, we talk a lot about the importance of energy efficiency and conservation. But, for a few hours every year, reducing our energy usage becomes especially important: on the hottest and coldest days of the year, energy use is the highest and electricity is dramatically more expensive and polluting. These high-demand days are called peak days, and we’re calling on our members to help us Shave the Peak by taking straightforward steps to reduce energy usage for a few hours on these days.

Peak Electric Demand: Expensive, Polluting, Inefficient

On a normal weekday, electricity demand fluctuates from about 10,000 MW during the middle of the night, when industry has shut down and people are sleeping, to about 16,000 MW from 4pm to 8pm, when stores are still open, lights are on, and families are cooking dinner, running dishwashers, and watching TV. Our electrical grid is really good at handling these day to day fluctuations in demand: it relies on nuclear power plants, natural gas, and some renewables (mostly wind) at night, and during the day it adds solar power and more natural gas to meet the increased need for electricity. Green Energy Consumers is working hard to increase the portion of our electric demand that is served by renewable energy through our Green Power program and our Solar program.

STP Normal Day Fuel GraphData for Tuesday, September 7, 2017. This day had hourly demand levels very similar to the average hourly demand for 2017. Data via ISO-NE Daily Generation Fuel Mix Report and 2017 SMD Hourly Report.


But the “normal day” doesn't tell the whole story. For a few hours every winter and summer, electricity demand skyrockets to almost twice the normal amount. These “peak events” are accompanied by wholesale electricity prices more than 10 times the average year-round price of electricity. In fact, just 1% of the year accounts for 8% of our energy costs, and 10% of the year accounts for 40% of annual costs. A number of New England's power plants operate for just 2 - 7% of the hours in a year. These plants--called "peaker plants"--stay in business by selling power at a very high price only during the hours when demand is greatest. Electricity during peak events isn't just expensive: it's also much dirtier than usual, because the grid draws on peaker power plants fueled by natural gas and oil that can rapidly ramp up energy production in response to the high demand.

State of Charge Peak Day Graph

The entire New England energy system is sized to meet the high demand that occurs only a few times per year. Graph via the 2017 Massachusetts State of Charge Report.


Let's take a look at how the electrical grid operates on a very hot summer day, like Friday, August 12, 2016, when temperatures soared over 95 degrees across New England for the second day in a row. As the day heated up in the early afternoon, homes, offices, and other buildings started blasting their air conditioning. At around 4pm or 5pm, demand spiked. Offices and factories continued to run, but now people were getting home and turning on their air conditioners, ovens, and TVs. In fact, electricity demand topped out at over 25,000 MW—almost twice the system average. To meet this sky-high demand, the grid operator, ISO-New England, ramped up not just natural gas production but also the oldest and dirtiest power plants of them all: oil plants. And when you burn fossil fuels when it's so hot out, air pollution gets even worse, causing dangerous smog and ozone health alerts.

Shave the Peak, Graphs_Fuel Mix on a Summer Peak Day, 8-12-16

Data from the highest demand day in 2016, Friday, August 12, 2016, via ISO-NE Daily Generation Fuel Mix Report.


Winter peaks are a little different. They don't reach the same high electricity peaks that summer peaks do (winter peaks usually max out at around 20,000 MW rather than 23,000 or 24,000 MW). But New Englanders use so much gas to heat our buildings during winter that the electrical grid struggles to buy enough natural gas to power its gas peaking power plants. And, again, the grid resorts to turning on oil-fired generators. The fuel mix chart below demonstrates how much higher our oil usage was on January 15, 2018 than in August 2016.

Shave the Peak, Graphs_Fuel Mix on a Winter Peak Day, 1-5-18

Data for Friday, January 5, 2018, the highest winter peak of 2017-2018, via ISO-NE Daily Generation Fuel Mix Report.


We’re already very far from having enough green power to serve the New England electrical grid on a normal day. On a peak day, we’re even further away. If we are truly committed to accelerating decarbonization of the electrical grid, we have to meet peak demand in different ways. We need to Shave the Peak.


Shaving the Peak

In New England, we usually know in advance when peaks will occur. ISO-New England forecasts electricity demand taking into many factors including weather. With these forecasts, we all, as energy consumers, can create an alternative way to meet peak demand by reducing our energy usage! We can do that by simple energy conservation efforts—or even by changing when we use electricity: by turning off lights, TVs, and electric ovens, turning down AC (or using fans instead). And if you own an electric vehicle, you have an extra ability to shave the peak by ensuring that you only charge your EV on off-peak hours.

By reducing total system demand during peak events, you’re helping renewable energy resources displace fossil fuels and thus meet a higher percentage of our electricity needs.

Through Shave the Peak, we can collectively make a difference. More importantly, we can pave the way for policymakers and utilities. Last summer, I and two of my colleagues at Brown University, Harry August and Lauren Maunus, wanted an easy way to reduce peak demand, so we set up a text-based system that would alert subscribers on peak days. After I graduated this past May, I joined Green Energy Consumers full-time to help them expand the initiative. You can now sign up for peak day text alerts or follow our advocacy efforts.

To sum up:

  • Peak days occur on the coldest days in winter and the hottest days in summer, when the grid operators have to turn on dirty and expensive power plants to meet skyrocketing demand.
  • Just 1% of the year accounts for 8% of the electricity costs, and 10% of the year accounts for 40%.
  • We don't have enough renewable energy to green up the grid during peak events. So we need to Shave the Peak.
  • You can help us Shave the Peak by signing up for peak alerts here and supporting our advocacy efforts as we push for a cleaner, more efficient grid.

If you have any questions, email us at!


 Shave the Peak: Sign up for electricity peak alerts