Emblazoned across the side of Seattle City Light vehicles is a logo, proclaiming it the "Nation's Greenest Utility." A cornerstone of that claim is that City Light is "carbon neutral."

Less known is that the City Light relies largely on carbon-free hydro and nuclear power, which account for about 94 percent of its energy, to make that claim. Ironically, these energy sources are not recognized as "renewable" by the state.

I'm not sure City Light is the "greenest" utility, but it is correct to count hydro and nuclear as carbon free. Washington state has very low carbon emissions due in large part to hydro and nuclear power.

Some greens, however, are questioning that 94 percent of carbon-free energy in City Light's portfolio.

In Crosscut, environmental activist Martha Baskin writes "The polite fiction that there's nothing controversial about the fuel mix of the Emerald City's public utility, Seattle City Light, is getting a new poke in the eye." She notes that some green groups want City Light to eliminate the 4-5 percent of energy it receives from Energy Northwest's nuclear facility in the Tri-Cities. This push, however, is at odds with the trend among many greens, like the Breakthrough Institute and Greenpeace founder Patrick Moore, who are concerned about climate change who advocate increased use of nuclear energy to cut emissions.

Explaining its support for nuclear, The Breakthrough Institute notes "the urgency of climate change has recently compelled liberals and progressives to reconsider nuclear as the best zero-carbon source of baseload electricity for a world with rapidly rising energy demand."

Of course, the greens quoted by Baskin hope the nuclear energy will be replaced with solar or wind power. That is unlikely. Nuclear power provides a consistent base load of energy and it is more likely to be replaced by natural gas, which is not carbon free.

Some aren't even happy with the 90 percent that comes from hydro. State Senator Maralyn Chase recently posted an article claiming hydro power is not carbon-free, writing that the claim is "troubling."

I asked City Light officials what they thought about the claim that "dams cause climate change." They responded:

Unlike coal- or natural gas-fired power plants, hydroelectric dams do not generate carbon emissions in their operation to produce electricity. The author of the article you shared wants to argue that methane from degrading biomass material that collects in reservoirs is caused by the dam. As commenters on the article noted, whether it will produce methane depends on the amount of oxygen in the water and the type of decomposition that takes place. This can happen in a river system without a dam also, so it is incorrect to attribute that release to the dam. Furthermore, the release of carbon emissions from the decay of biomass is part of the cycle of existing carbon in our ecosystem.

Again, none of that even addresses the question of what would replace all that carbon-free energy. There is no analysis anywhere claiming that hydro, wind, biomass, conservation or any other sources of carbon-free energy in combination could replace 90 percent of Seattle's energy. The only available replacements are all carbon-intensive.

Taking steps in this direction would simply be cutting off our nose to spite our face.

Left-wing environmentalists often claim climate change is the most important issue of our generation. Instead of focusing on workable solutions that address the real sources of concern, like transportation, many greens get sidetracked by ideological purity efforts that distract from, and undermine, real efforts to make progress.

If we are serious about addressing carbon emissions, we need fewer of these wild goose chases.