The Climate in Emergency

A weekly blog on science, news, and ideas related to climate change

The Good News from Facebook

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The other day, I saw a Facebook meme that included the following text:

There are 14.8 GW of solar currently installed in the US, which is enough to power three million homes and reduces carbon emissions equivalent to taking 3.5 million vehicles off the road or shuttering more than 4 coal-fired power plants.


The meme was created by an entity calling itself The SolarIndustry. Of course, this seems to be good news, but the phrase “enough to power three million homes” bothers me. The statement as a whole is interesting food for thought, too. So, let’s unpack this thing a bit, shall we?

First,I should say that I don’t know whether the quoted statement is true. Its accuracy is not the point of this article.

Also, please note that ‘watt’ (and therefore ‘kilowatt’ and ‘gigawatt’) is a measure of the flow of electricity, not an amount. If a pair of LED lights each use 1o watts, that means they use electricity at the same rate, but if one is on twice as long as the other it will use twice as much power. This is why I use gigawatt-hours (gWh), not gigawatts, and kilowatt-hours (kWh), not kilowatts, throughout the article, except when referring to The SolarIndustry’s statement.

How Much Is Enough for Three Million Homes?

Obviously, “three million homes” is simply The SolarIndustry’s way of helping the reader understand what 14.8 gigawatts really is. Measuring electricity use in homes is kind of like measuring area in football fields–it’s something most people can picture easily. The meme didn’t mean that there are precisely three million solar-powered homes out there.

But The SolarIndustry goes on to say that we have enough solar capacity to “shutter” four coal-fired plants. While this, too is a figure of speech, not a statement about specific power plants, the point is obviously that adding solar-generated electricity has the power to subtract a corresponding amount of coal-generated electricity. As if solar energy could chase away fossil fuels simply by existing.

Solar energy can’t do anything of the kind.

The problem is that the American energy market isn’t a zero-sum game. These kinds of claims make it sound as though a given amount of electricity could be “enough to power a household” in the same way that eight ounces of water is enough to fill a cup.

But that isn’t what ‘enough’ means in this context. If it were, then the average residential electricity customer would use about 14 kWh per month, because that’s about how much you need to replace kerosine lamps with LED fixtures. That’s what residential electricity was mostly used for, in the beginning–to replace kerosine or coal-gas light fixtures. The actual figure for an average American house for a month in 2012 was 903 kWh, because if people can afford a given amount of power, they generally find a use for it. The cup has no bottom. It can’t be filled.

Adding solar power generation capacity is an important tool in switching away from fossil fuels, but it cannot, all by itself, trigger the switch. Without other social, economic, and policy changes, the only thing that adding more solar can do is increase total electrical generation capacity–driving the cost of electricity lower and increasing demand.

The only way to shutter coal plants is to buy less electricity from coal plants.

What 14 Gigawatts of Solar Really Means

The actual figure for solar electricity generation in the US in 2013 was 9333.4 gWhs. That sounds like a lot, but it’s only .23% of total US electricity generation.

We get 13% of our electricity from all renewables combined; the rest is fossil fuel and nuclear power. We could calculate the number of houses that is “enough” for, but as we have seen, no amount of energy is really ever “enough” because demand can increase infinitely. Consider that 200 years ago, the demand for electricity was precisely zero.

To get a real sense of how far our renewable energy can go, we need to turn the calculation around–stop asking how much of current demand renewables can cover and start asking whether we can live within the energy budget renewables offer us. If we were willing to cut our total electrical usage to 13% of what it is now, we could get both fossil fuel and nuclear out of our electrical grid tomorrow.

So What Is the Good News?

Increased solar capacity really is good news, just not for the reason The SolarIndustry gave on Facebook. The issue is that we will only get off fossil fuel as a society when we limit our energy use to what other, climate-friendly, sources can give us. Probably, though will require some kind of legal changes, and it will definitely require social and economic changes. Such shifts will only be politically feasible when we have enough alternative power sources to give us a lifestyle we can accept culturally. We could try using no electricity and no machines at all except those driven by muscle power, but most people wouldn’t accept it.

But the more renewable capacity we have, the less jarring getting off fossil fuel would be. Already, cutting out fossil fuel from the residential electricity market would be doable, if the existing capacity were distributed properly (I do not know about commercial, industrial, or military use).  My husband and I, for example, use about 130 kWhs per month, which is just 7% of the national average–and in point of fact, we get all of it from renewables through our local electric company. We don’t feel deprived. We have efficient appliances, we hang-dry our wash, we heat with wood (another topic!), and we turn things off when not in use.

The argument that we somehow “need” fossil fuel because without it we’d all be back in the stone age is getting less and less tenable all the time.


Author: Caroline Ailanthus

I am a creative science writer. That is, most of my writing is creative rather than technical, but my topic is usually science. I enjoy explaining things and exploring ideas. I have one published novel and another on the way. I have a master's degree in Conservation Biology and I work full-time as a writer.

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