How dirty IS coal?

For some time now, natural gas has been the fossil fuel of choice for the green-minded energy company or power plant. When burned, natural gas (overwhelmingly methane, with a smattering of heavier components) gives off the least carbon dioxide (CO2) per unit of energy (let's call it Btu). Gasoline produces about 30% more CO2 per Btu and coal produces almost two and one-half times the CO2.

Natural gas needs no refining, is far safer to use and handle than propane, and we can import it in special insulated tanker ships as LNG. Natural gas produces zero ash, while coal...well anyone who's seen the dirty brown plume from a coal-fired power plant knows it's enormous.

What's not to like about natural gas?

Technical alert: some chemistry follows! You can skip to conclusions, a few paragraphs down if you want.

Methane is, chemically, the simplest of the hydrocarbons which comprise all fossil fuels. It consists of one atom of carbon bonded to four atoms of hydrogen (CH4). Carbon dioxide consists of one atom of carbon bonded to two atoms of oxygen (CO2). But oxygen is much heavier than hydrogen. Consequently, when you burn a pound of methane, you get 2.75 pounds of CO2, some water and about 23,000 Btu of heat.

How does coal compare? Well, coal is almost pure carbon plus non-combustible minerals which become smoke stack particles and ash when it's burned. The ash content varies from field to field, but let's assume it's 5%.  When we burn a pound of coal, it produces 3.7 pounds of CO2, no water and about 13,000 Btu. That's right, pound-for-pound, we get more heat AND less CO2 from natural gas than we do from coal!

What if we compare them on a Btu basis? Well, if you have some math aptitude, you can see where this is headed. To get a million Btu (enough to generate about three days' power usage for a typical house), you have to burn 77 pounds of coal or forty three pounds of natural gas. That forty three pounds of gas produces 119 pounds of CO2 while the 77 pounds of coal produces a whopping 282 pounds of CO2. In other words, coal produces almost two and a half times as much CO2 per unit of energy. As an added bonus, you get almost four pounds of ash.

So why would anyone want to build power plants fueled with coal? Oh, you already know the answer - coal is CHEAP compared to natural gas, at least if you ignore the environmental aspects. And up to now, that's exactly what our political leaders have done.

So what can we conclude from this? First, coal fired power plants are poison to our environment and we should fight them in every legal way we can. But second, while natural gas is much better than coal, it still produces a HUGE amount of CO2. A medium sized power plant requires around a million TONS of natural gas per year, which produces almost three million tons of CO2. Folks, we better start thinking about something other than fossil fuel to generate our electricity.

There are many possibilities for generating electricity that don't pollute - wind turbines, solar power, tidal power. Most of the so-called drawbacks that these potential sources of electricity entail is, they don't readily conform to the huge central power production and distribution system paradigm that we've come to rely upon. That is, these production sources are more suited to smaller users or groups such as small towns, or neighborhood coops. Of course, the huge electric power utilities hate this idea.