When I was shopping for a solar panel array I noticed something. In every proposal, right near the top was a paragraph bolded and underlined entitled something like "Environmental Benefits of your system." In one of my proposals it declared that over 25 years the system would offset "170,877 kWh of fossil fuel based electricity (estimated projection)." It continued, "This will result in a reduction of: CO2 emissions by a minimum of 268,056 lbs... the environmental equivalent of 436,153 miles driven in an average car or planting approximately 2.3 acres of trees." The representative explained that she arrived at these numbers simply by calculating the amount of electricity the system is estimated to produce over the 25 years and then noting how much fossil fuel would need to be burned to create that same amount of electricity.
We certainly need much more solar power here in the US, but my concern is that this claim of one to one emissions reduction is simply not the truth - especially where I live. As of 2014 67% of Ohio's electricity still came from traditional coal plants (source: http://www.eia.gov/state/?sid=OH). In order for the claims above to actually be true, for every electron made by the solar panels, the coal plant operators would have to respond almost immediately by burning just a little bit less coal. I thought to myself, "Is that even possible?" And so I started to investigate as best I could. Quickly it became apparent that adding a home battery to the situation was really the way to go if I wanted to be sure that the electricity made by the solar panels was indeed offsetting fossil fuel use. In the posts that follow I take you on the journey that lead to this conclusion. The need for home batteries is one shared by many researchers and grid policy consultants, but is buried in technical reports and jargon which make it almost impenetrable to the average consumer. My goal for this website is to present the case for home batteries as a driver of lowering one's carbon footprint in a manner that is understandable to anyone and everyone. Below I present an example of an instance in which electricity from solar panels in Arizona did not result in less fossil fuel being burned, but first just a bit of quick background.
A traditional coal plant is a huge operation. It can change the amount of coal it is burning, but it needs advance notice, kind of like steering a cruise ship. However, the electricity made by solar panels can change on a dime (see for example: clouds) - much faster than a coal plant can respond. Therefore a person controlling a coal plant will often be loathe to commit to turning down the plant, knowing that they might get left "with their pants down" so to speak if the electricity being made by solar goes down too fast. Another complication is that the very act of turning up or down any kind of power plant costs money, further disincentivizing the practice of actually lowering the amount of coal burnt.
The people who actually decide how much a power a power plant should make and when they should make it is called a "grid operator." As an example of just how hesitant grid operators are to actually turn down their fossil fuel plants, check out this recent article from the Phoenix area (July 2016): http://www.azcentral.com/story/money/business/energy/2016/07/08/summer-heat-builds-aps-traders-balance-grid-power-various-sources/86359780/.
Quoting the article above: "In winter, power demand peaks in the morning and again in the evening. During midday, when power demand is low, the solar units generate so much electricity that utilities will pay their neighbors to take the excess power. It is cheaper to pay them to take the power than turn down their natural-gas plants, which will need to restart later in the the day. "We saw that a lot this spring," Albert said, "We see it when customer (electricity use) is a lot lower and renewable (i.e. solar) generation is high." One day in April, (a grid operator) actually earned $69,000 from neighboring utilities for taking their excess solar power. Because (the grid operator) has substantial solar in its territory on customer roofs as well as its own large (solar) plants, it didn't necessarily need the power. But (the grid operator) shut off some of its solar plants to make room for the power and the payments for taking it, which reduced costs to (the grid operator's) customers that day..."
Note that in the example above, it is a Natural Gas power plant they are talking about, which is supposed to be a lot easier to turn up and down than a coal plant, but they still didn't want to turn it down!
And so when my solar installation company assumes that every single watt of electricity made by the panels results in a 1:1 reduction of CO2 emissions they are making an assumption that simply cannot be true.
So what is the truth? Is the reduction 90%? 70%? 50%? Finding the answer to this has proven extremely complicated. In later posts I examine the evidence that is available to the general public (actual data from the utilities themselves is typically hard to come by). I don't want to demonize solar installers though - as we will see we definitely need more solar power. It's just that solar power is only part of the answer.
I don't want to demonize grid operators either. Every single day they have to make an educated guess on how much coal to burn. There are options (as in the example above) to get rid of extra electricity but if they are caught with too little electricity it can cause power outages, thousands of angry customers, and federal fines to boot! So grid operators have a laser-like focus on never having too little electricity. And when are they at greatest risk of having too little? During the peak electrical demand for the day. When electrical demand peaks for the day, it is their job to be sure they are ready to respond. There are whole legions of grid operators whose entire job is to try and predict what (and when) this peak will be the following day. They look at data from the days preceding, at historical data, and at the weather forecast (among other things). Needless to say however, the incentive is to err on the side of caution, and make sure they're burning enough coal to meet that peak demand.
So where do Home Batteries fit in to all of this? Peak electrical demand is usually in the early evening. A home battery can store the electricity from the sunny daytime and then use it during the evening, thereby lowering peak demand. This is known as "Peak Shaving." My argument is that over time if more and more people were to use home batteries to "shave their peaks" then grid operators would soon take note. They would know in advance that the coal plant doesn't need to be prepared to meet as high of a peak demand. Then and only then would the grid operator feel comfortable actually turning off a coal plant instead of leaving it idling (and thus still burning coal).
Now not all of our electricity comes from coal (though most of mine does). And so in the posts that follow I examine all kinds of generation - from coal and natural gas to nuclear and renewables. How best can a homeowner reduce the CO2 emissions from his or her electricity use? I look at this from multiple perspectives, including from the perspective of a single homeowner but also from the perspective of a grid operator managing thousands of homes.
There are other benefits that home batteries can provide beyond what I've described above, including a near instant ability to provide back up supply to the grid during a problem, an ability to make use of excess electricity generated during times of very low demand, and of course the ability to provide emergency back up power to your home. All of this and more will be fleshed out.
One final note - for someone who is buying solar panels to save money on their electric bills (a perfectly reasonable thing to do) then nothing on this site matters. However, for someone buying solar panels in an effort to reduce their carbon footprint both for themselves and for the collective future of this country - this site matters deeply.