There is no such thing as completely "green" energy. All forms of electricity generation have some detrimental environmental impact - some relatively little, some enormous.
One of the most closely watched effects is emissions of carbon dioxide - the sort of thing that makes fossil fuels like coal and natural gas notorious.
Levels of CO2 in the atmosphere are linked to rises in Earth's temperature, and thus to global warming, climate change and all that. Fossil fuels belch plenty, as the chart above shows. It illustrates how many tonnes of CO2 are emitted per gigawatt hour of electricity generated by different generating technologies.
The chart is a "lifecycle" analysis that takes into account CO2 emitted not only during electricity generation, but also by the mining, manufacturing, construction and other processes it takes to get a power plant up and keep it running.
It's no surprise that coal and natural gas tower above the others. But some of the other marks might raise a few eyebrows. "Renewable" power sources solar PV and biomass are both more CO2-intense than nuclear, as is hydro. Nuclear is on a par with geothermal, and virtually the same as wind.
The chart was presented earlier this month by Nobel-winning Stanford University physicist Burton Richter, at a "Science Day" hosted by French utility EDF in Sausalito, Calif. It's not new - it was first put together by a group of PhDs from the University of Wisconsin in 2002. But its findings still hold true (note, however, that it does not include "tidal" or "solar thermal" - I'd be interested to see those and others added to the comparison).
Alex Cannara, an independent energy and environment analyst based in Menlo Park, Calif, wrote an articulate comment after a recent Bloomberg story about nuclear power, in which he explains the spirit and to a large extent the letter of what Richter's presentation shows. Bloomberg had written that nuclear power is all but finished in Europe, quoting a Paris-based consultant saying that nuclear is "too capital intensive, too time-consuming and simply too risky." Here's Cannara's rebuttal:
Hope they didn't pay this 'consultant' much for: “Nuclear is too capital intensive, too time-consuming and simply too risky.”
Germany thinks it's ok to emit tens of mega-tons more of CO2 because they like coal & ligniite better than nuclear? Remind us how many Germans have died from nuclear-power radiation. What about Americans? English? French? Oh yes, all zero.
Whoever wrote the advice above seems ok with the deaths and disease from combustion, mining, etc. -- all things needed for windmills, by the way.
So when we see German coal & gas burning costing ~180 years of human life per TW-hour, we should say that's ok, despite German nuclear costing less than 1/6 those years of life? Really?
Remember, making 1 large Siemens windmill requires processing about 2000 tons of materials via fossil fuels -- steel needs coal and iron ore, etc. Concrete needs kilned limestone & mined/crushed aggregate., etc. So the emissioins burden of wind is higher than nuclear. And we're not even talking about the vast tracts of land/sea taken for wind. Nor are we talking about species threats, maintenance emissions, worker dangers, and even maritime dangers for offshore windmills.
And here we thought the Germans the smartest -- must have been some PR, or the beer.
Cannara's valid points hold up even more when you take into account the alternative nuclear technologies that could replace the conventional variety that has been operating for 50 some years. Reactor designs like molten salt, pebble beds and fast reactors augur a number of advantages including the conversion of nuclear "waste" into fuel, the reduction of long lived dangerous waste, failsafe meltdown-proof opeations and others. So could the use of thorium fuel instead of uranium. And the dream of fusion power is achievable.
Safe nuclear power, as well as other sustainable energy technologies, all belong in the future of a CO2-light economy.
Images: Chart is from Burton Richter via University of Wisconsin. Photo from Burton Richter/NSF via Wikimedia.