The “bridge” fuel that wasn’t

Among those who spend their working lives and/or spare time worrying about climate change, there are many subjects that still provoke heated debates, so to speak. Chief among them is the wisdom or folly of turning to natural gas as a “bridge” between the carbon-intensive oil- and coal-dominated present and the clean renewable future that we all know is coming sooner or later. The opponents just found their case a little bit stronger thanks to another controversial issue: nuclear power.

Natural gas is, as anyone with a basic grasp of the fundamentals of greenhouse gas forcings can tell you, only  half as good at warming the atmosphere as coal. So replacing coal-fired plants with natural gas alternatives should get us half-way to cutting our emissions to zero. Right?

Well, not quite. Natural gas is almost entirely methane, which has 20 times the warming potential of carbon dioxide over a century, and several times that in the near-term. And as all operations involving natural gas also involves some release of methane directly into the air, the effect of that methane has to be added to the calculations used to compare the emissions impact of each fuel.

Let’s say for argument’s sake an operator could get “fugitive” emissions of methane down to 1 or 2 percent, which is quite possible, though much lower than what is probably the industry norm these days. Consider also that gas-fired plants are more efficient than coal. So the best-case scenario is gas will cut the effective warming of gas by 30 to 40 percent. Whether that is sufficient given the amount of time we have left before triggering irrevocably serious climate change is also a matter of some debate. After all, we know we need to get to zero, so why pour scare resources into switching to one alternative only to spend even more in a decade or so to switch again?

But all this is only relevant when comparing gas with coal, which supplies only about 40% of the American electricity mix. What about nuclear power? Its carbon footprint is measurable, but tiny compared with coal. So if you replace a nuke with a gas-fired plant, you’ve increased your emissions budget from near-zero to 100% of whatever the non-nuclear alternative was.

Geoffrey Lean at the Telegraph asks “Is shale gas killing nuclear power?” Several nuclear power plants in the U.S. are being replaced by gas, undoing a significant portion of whatever minor advantage gas presents in the effort to reduce carbon emissions.

Add to this the complicating factors of the cooling aerosols associated with coal, and natural gas is starting to look more than a little problematic.

Yes, natural gas can provide real carbon-emissions reductions in some situations. It’s relatively easy to install, the technology is well understood, and it’s a fossil fuel, so the status quo doesn’t feel so threatened. But the math suggests it isn’t going to do the trick.