The "green" movement is once again wanting the earth to go dark for one hour. This year's Earth Hour will be on March 31, 2012, at 8:30 pm (local). This means that each time zone will have it's own hour (traveling around the earth like a "wave").
How effective will this darkening of the earth be? Since this is being done to convince people that the "evil" CO2 is the sole cause of all the earth's extreme weather events, let's look at how much CO2 will be eliminated.
Let’s look at the results of last year’s effort, specifically in the province of Ontario, Canada.
Ontario’s Independent Electricity System Operator (IESO) reported that that on March 26th, 2011, between 8:30pm and 9:30pm, due to conservation action during the last episode of Earth Hour, province-wide demand for electricity fell by 360 megawatts or 2.1% compared to a typical Saturday evening in late March.
Let’s simply assume that all 360 MWh of power demand was actually eliminated, rather than being merely postponed. Since it would be difficult to quantify the impact of time-shifting household activities, let’s just be generous and ignore it altogether.
How big a deal is 360 MWh? At Ontario’s blended average retail electricity price of 7.74 cents per kWh, that 360 MWh of reduced consumption amounts to a province-wide total cash savings of $24,864. One could, perhaps, compare that savings to the money spent promoting Earth Hour in Ontario by the WWF, various levels of governments, and numerous corporate partners, to say nothing of the costs incurred by the individual participants. But I don’t imagine that would be a favorable comparison.
So cost savings aside, how big an impact did Ontario’s Earth Hour have on the province’s CO2 emissions? Let’s ignore the extra emissions generated by people who traveled to and from public gatherings, or by those who lit paraffin wax candles (each of which emits about as much fossil-fuel derived CO2 per hour as a compact fluorescent light bulb). For simplicity, we’ll just focus on the CO2 emissions from the electricity that was saved.
According to the Environmental Protection Agency (EPA), non-baseload electricity emits an average of 690 g of CO2 per kWh into the atmosphere. So, by simple math, by conserving 360 MW of electric power during Earth Hour, Ontarians reduced their CO2 emissions by a total of 248 metric tons.
248 tons. That sounds pretty impressive, doesn’t it? And it isn’t really that difficult to achieve - in fact, it’s even kind of fun. Perhaps we could just have a few more Earth Hours each year, and have some real impact on our emissions reduction targets. So, how many Earth Hours would it take? Once every quarter? One per month? Weekly?
In 2007, Ontario introduced its Climate Change Action Plan action to reduce total GHG emissions. This action plan established an annual GHG reduction target “6% below 1990 levels by 2014, a reduction of 61 megatons relative to business-as-usual” (pg 6). By eliminating 248 tons of CO2 emissions, Earth Hour achieved 0.000407% of this target.
Or, looked at another way, it would take nearly 246,000 Earth Hours to achieve the province’s annual emissions reduction target. Unfortunately, there are only 8760 hours in a year, so it would require a little more than 28 years of sitting in the dark to make good on a single year’s emissions reduction target. The WWF certainly isn’t kidding when it asks Earth Hour participants to sustain their actions “beyond the hour.”
If you look at it another way, the switch to DST has the same effect - once per year. The "spring forward" would save the same amount of CO2 as the "earth hour" does (that 248 metric tons). Of course, the "fall back" ADDS that much CO2 (248 metric tons) to the earth, leveling it out.
One more thing - how many of you enjoyed your every-four-years Leap Day? That "extra day" added 5,952 metric tons of CO2 to the earth.