A common refrain, from skeptics to allies alike, is that renewable energy is a great idea, but not feasible because oil, gas, and coal will always be cheaper. Leaving aside the fact that fossil fuels are a finite resource and are the primary driver behind a warming planet, is it really true that renewable energy is more expensive?

Brian McConnell made a graph that shows what has happened to the price of energy (in gigajoules) since 1980 for solar power, natural gas, crude oil, and then residential electricity.

In his words:

The graph above compares the price history of solar energy to conventional energy sources. This is what a disruptive technology looks like. While conventional energy prices remained pretty flat in inflation adjusted terms, the cost of solar is dropping,fast, and is likely to continue doing so as technology and manufacturing processes improve.

That green line drops steadily. Though it represents a very tiny proportion of the total energy mix, as it gets cheaper and cheaper we can expect that to change. Disruptively. One thing McConnell said he would like to update is prices for coal, which would be interesting.

In an update, he noted that while joules are a good leveling metric, one thing they do not capture is the fact that many of those joules of fossil fuel energy are burned as waste heat, increasing the price. Solar placed in less sunny places than the American South would also increase the price.

His graph is backed up by the pros. In Bloomberg New Energy Finance’s presentation (pdf) to the Clean Energy Ministerial last month, this slide shows that solar panel prices fell 80 percent in the last 5 years:

It’s not just solar. This one shows the steady decline in wind turbine prices – 29 percent since 2008:

The skeptic might say “that’s all well and good, but storage technology is not feasible and what exists today is far too expensive — some cars will always need gasoline.” Not so: lithium-ion battery costs dropped 40 percent in the last three years:

(HT CleanTechnica)

Again: there is one kind of energy that gets more expensive the more it is used, and one kind that gets less expensive the more it is used.