Lifting the Grid: Solar Vs Grid Demand During the hot week of July, 2013
Solar Power | August 7, 2013 |Posted by Fred Greenhalgh
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As a follow-up to our discussion about our work installing solar in the blazing heat, we crunched some numbers about grid consumption and solar production during the record-setting days of heat July 16-19, 2013. What we found confirms the basic assumption – when the grid is stressed out to the max, solar gives back.
Where Power Comes From
Electricity is a funny commodity in that most homeowners have a greatly delayed feedback loop between when they use the service and when they pay for it. The time delay between flicking lights on, consuming kilowatt-hours, and then being billed for those kilowatt-hours nearly a month later makes it hard to understand the cause-and-effect relationship.
While our actions have a delay, under the hood, the grid is being monitored on a minute-by-minute basis with extremely sophisticated equipment that measures hundreds of variables. To maintain stability, the grid needs a certain amount of ‘base load’ power, but it also needs to be prepared for spikes in demand that occur when equipment fails, or when there are sudden spikes in demand.
While the wintertime is Maine’s peak heating oil and propane season, cooling is performed using electricity, making summer the peak season for electric demand. An influx of summer tourists, rising expectations about air conditioned space, and increasingly frequent high heat events all combine to put incredible pressure on the grid.
Sweltering temperatures and high humidity from July 14 through July 20 sent electricity demand soaring and set some new records for power use. At the onset of the week, ISO system operators forecasted very high demand for electricity—the highest of the season—and tight power system conditions were expected throughout the week … New England didn’t exceed the all-time peak demand of 28,130 MW set on August 2, 2006; however, several days did make it into the record books:
Two weekdays made the top-10 peak demand day list:
Thursday, July 18: peak demand was 26,867 MW (ninth highest)
Friday, July 19: peak demand was 27,360 MW (fourth highest)
Meeting power demands on these peak days is no small feat, and the conventional utility approach is to fire up reserve power plants. This source of contingency power is typically the worst-of-the-worst: oil-burning power plants, such as Wyman Station on Cousins Island.
The cost of firing up these stations is two-fold. First, they are among the worst environmental offenders, spewing and average of 1,672 lbs of carbon dioxide, 12 lbs of sulfur dioxide, and 4 lbs of nitrogen oxides per mWh of production (source: EPA). Second, as every New Englander knows, oil is expensive, and firing up these power plants causes extraordinary spikes in the cost of electricity:
However, the production of this peak electricity is only part of the cost. The other portion of the cost is that of distributing it. Conventional power plants are not located near population centers for a number of sensible reasons, but that means that the power needs to be delivered to the end customer.
The traditional solution? Expensive grid upgrades, such as CMP’s $1.4 billion MPRP transmission project that is currently underway. These transmission projects require the utility to build massive infastructure based on ‘worst case’ load forecast twenty years in advance, often leaving ratepayers stuck paying costs when those forecasts turn out to be wrong.
A Bright Solution
So we need power when it is hot – which is, by definition, when the sun is out. This unique property of solar power (compared to wind, which actually has to be dialed down at times to deal with lack of distribution lines) as well as its generate on site makes it a powerful combination for easing the strain on the grid. Surely there is a way to combine solar opportunity with the grid’s desperate need for more electricity on hot days?
Consider this – in red we see the demand from the grid, in green we see the production of a solar electric array installed by ReVision Energy at Falmouth High School:
Solar provides electricity exactly when the grid needs it. Imagining that there was enough solar power out there to meet all of the excess peak electricity, how does solar match to the peak electrical costs? See below – the solar again is green, the cost we, as ratepayers, pay for electricity is in blue:
Not only is the solar energy resource available exactly when we need it, but it also is available during the sunny days when the grid is not peaking. Despite the compelling opportunity, the development of a smarter grid that generates and uses power locally is in its infancy. The first project of this type in Maine is currently underway in a distributed grid project in Boothbay.
The test ‘non-transmission alternative’ project was green-lighted in a CMP settlement with the PUC in 2008 that also resulted in the approval of the much larger $1.4 billion grid upgrade project. While off to a slow start, the project is showing promising results already – business owners are undergoing efficiency upgrades that will save them thousands of dollars a year, with a projected savings of “$78 a kilowatt [per LED electric bulb] versus $1,500 a kilowatt for building a new power line.” (Source: Portland Press Herald). Maine’s primary distribution utility, Central Maine Power, is actively participating in the Boothbay Pilot Project in order to learn how a transmission entity such as themselves can work most effectively with distributed generation sources such as solar.
This kind of redefined vision of power distribution is in its infancy in Maine, but in more expensive energy markets, such as California and New Mexico, solar + distributed generation, with no subsidies and on a cost-competitive basis alone, is nearing grid parity.
Even without a more substantial distributed grid roll-out, each and every solar electric array helps to ease the demand on the electric grid on hot days. At minimum, a solar electric array will offset cooling demand for a solarized home, and in most cases, our customers are feeding power back to the grid to power their neighbors’ air conditioners while simultaneously running their own!