TUCSON, AZ (Tucson News Now) - It's the end of an era.
On Thursday, Tucson Electric Power began burning the last five tons of coal at its power plant on Tucson's south side. TEP said the price of natural gas is competitive with coal, and actually has been for a few years.
TEP spokesman Joseph Barrios said, over time, there's no telling where natural gas prices will go but for now, TEP customers should not see an increase in their electric bills.
The last of TEP's coal supply went into the plant's Unit 4 on Thursday.
TEP's other three units already burn natural gas. There are some trade-offs, however.
Officials with TEP said over time, it will lose some flexibility. It won't be able to switch back to coal when natural gas prices rise. TEP can produce about 30 percent more electricity with natural gas than it can with coal.
Another trade-off is that natural gas emits about half the carbon dioxide that coal does.
Plus, officials said if it had not switched away from coal, the Environmental Protection Agency would eventually have required the utility to install emissions control equipment.
TEP and the EPA agreed on the switch to natural gas.
"The cost of natural gas is low right now and if we would've installed that emission control technology at the plant, that could've cost tens of millions of dollars maybe hundreds of millions of dollars, depending on what would've been required. And so, again, this made sense from an environmental perspective, in terms of cost efficiency and reliability," Barrios said.
TEP does use some solar power, landfill methane gas and solar steam in its Unit 4.
Some might wonder why the utility doesn't just switch entirely to renewable energy. Barrios said it's a question of reliability, and there's no good way to store energy for when you need it.