Energy, it seems, is something we always need more of. Now, as utilities gear up to build new power plants, the EPA has put a cap on how much carbon dioxide a new power plant can release for every unit of electricity it injects into the grid. The new regulations put strong constraints on new power plants.
Nearly all electricity is produced by spinning a generator (most notable exception: solar panels). Power plants differ in what makes the generator spin: Wind, water, steam, combustion gases.
Wind, water and nuclear put no CO2 into the air; burning fuel, does.
A ball would “rather” sit at the bottom of a hill than at the top (“rather” in quotes because balls are brainless – they have no druthers, but simply follow the laws of the universe). Given half a chance, a ball “happily” rolls downhill, releasing energy as it rolls, energy to crush the grass beneath it, energy to knock down things down.
All matter is made of atoms, bonded – “glued” – together. What makes a substance a fuel is that its atoms would “rather” be bonded, not to each other, but to atoms of oxygen.
Make fuel hot – with a match or with fuel burning nearby – and its atoms break the bonds holding them together. The loose atoms are then free to re-bond to atoms of oxygen. As they “happily” re-bond, they release energy.
Coal is composed predominantly of carbon atoms. When an atom of carbon bonds with two atoms of oxygen, the result is carbon dioxide.
Natural gas is composed largely of methane – a molecule built of four hydrogen atoms bonded to one carbon atom.
When methane burns, its lone carbon atom bonds to two atoms of oxygen, forming carbon dioxide (CO2) and releasing energy.
The hydrogen atoms also bond to oxygen atoms, two hydrogens to one oxygen, forming dihydrogen oxide (H2O - water), and releasing energy.
With a good amount of its energy coming from the hydrogen-oxygen reaction, burning methane (in natural gas) releases only a fraction as much CO2 as does burning coal.
Measuring how much energy – how much heat – comes from burning a fuel, one can calculate how much water it will boil, how much steam it will produce, how much electricity it will generate, how much carbon dioxide will go up the stack.
Burning coal, with present-day technology, cannot generate electricity without producing more carbon dioxide than allowed by the new EPA regs. Unless utilities are willing to invest in unproven technology, new power plants will not burn coal.
Less than a decade ago, the supply of domestic natural gas was dwindling. Energy companies were attempting to license terminals up and down the coast to import liquefied natural gas (LNG). LNG was expensive.
Over the past decade, hydraulic fracturing – fracking – has expanded the domestic supply of gas such that the price has dropped to roughly a quarter what it was a decade ago. Companies once hoping to build terminals to import LNG are now hoping to build – on the same sites, using much of the same equipment – terminals to export LNG.
(The possible environmental and health effects of fracking are the subject of intense debate, and protest. I’ll devote future columns to those issues).
Carbon dioxide is a greenhouse gas, but, in our present atmosphere, not a very strong one. The debates over the possible effects of CO2 on climate hinge, in part, on how the small amount of warming that CO2 might trigger could be amplified by other, more potent greenhouse gases.
One of those more-potent – much more potent - greenhouse gases is methane.
Fracking as well results in more gas leaking to the atmosphere than does in conventional natural gas wells. The EPA recently released data showing that such leakage is less than – and will have less greenhouse effect than – what had previously been reported. This in response to a calculation performed several years ago by ecologist Robert Howarth of Cornell, who found that the greenhouse effects of “fugitive methane” could warm the atmosphere more than simply burning coal.
Al Stahler’s science programs can be heard on KVMR (89.5 FM). He teaches classes to students of all ages, and may be reached at firstname.lastname@example.org