Earth Hour 2014 will be celebrated today, Saturday, March 29. It started in Sydney, Australia in 2007 as a lights-off event. It is largely a symbolic event signalling an environmentalist commitment. There is an internal contradiction, however, in the manner it is typically celebrated–by substituting electric lights with candles. For example, celebrations in Toronto will include candlelight walks and concerts.
Most candles today are made of paraffin wax. When burned, each candle emits about 11g of carbon dioxide per hour. According to the EPA, the US electric grid in 2010 put out, on average, 1.23lb of carbon dioxide per megawatt-hour. This translates to 0.0000738lb, or 0.0335g, of carbon dioxide for one 60 watt incandescent light bulb per hour–or over 300 times fewer emissions than a paraffin candle.
The Earth Hour website suggests the use of beeswax or soy candles arguing that they are effectively “carbon neutral” since “the CO2 they emit has already been taken from the atmosphere to produce the wax,” but this is misleading. In the case of beeswax, bees do not directly remove carbon dioxide from the atmosphere. It is removed from the atmosphere earlier in the chain, by the plants exploited by them; neither does the carbon trapped in beeswax typically reenter the atmosphere. Beeswax is largely undigestable by both larger fauna and microbes and denatures only at temperatures at 250F or higher, so the sun (by heating) will never naturally release its carbon. Therefore, the natural carbon cycle finds a dead-end in beeswax unless it is released by burning.
Soy wax has a lower melting point and is much softer than other waxes, which means it is often mixed with paraffin wax (depending on the type of candle). It is often claimed to be biodegradable, along with beeswax, but, as far as I am aware, there is no clear evidence of this (I welcome being proved wrong!). But this eschews the important point that soy is farmed, which in itself entails various carbon costs. It is unclear to me whether the carbon footprint of farming soy offsets its benefits, but it is something that should be determined before promoting soy candles for Earth Hour.
So-called fossil fuels, while originating very differently, too are naturally permanent traps for carbon. Burning a different natural carbon trap (beeswax) and releasing carbon dioxide is no different than burning any other hydrocarbon.
The Earth Hour website also mentions an increasing movement to use LED lights instead of candles for various Earth Hour events, but let’s hope they are either using rechargeable batteries or plugging the lights right into the electricity grid, since disposable batteries too have a significant environmental impact. Unfortunately, this is too much to hope for, at least for the US. According to a 2011 report by the National Electrical Manufacturers’ Association, 80% of portable batteries produced in the US are alkaline batteries (p. 2), 87% of which end up in landfills (p. 19). For each kg of alkaline batteries produced, an average of 0.6kg of carbon dioxide is released into the environment (p. 27).
As a point of comparison I will use the Streamlight Siege LED lantern. Although its output in lumens is 340, about a third of what one would expect of a 60 watt incandescent bulb, it will serve to illustrate the point. It runs on three D cell batteries, which, give or take a few, will weigh in together at around 450g. The manufacturer suggests a run-time of 30 hours set on high. Therefore, an operational time of one hour has a carbon footprint of 1/30 x 0.45 x 600g, or 9g–provided that those D cells are replaced at some future point. This is 269 times more carbon emission than plugging a 60 watt incandescent bulb into the power grid. Running the lantern at low power extends the lifespan to 295 hours, with a footprint of 0.09g, still about 2.7 times that of the 60 watt incandescent bulb and 24 times less light.
Using rechargeable batteries changes things dramatically, but it will never have a smaller carbon footprint than simply plugging an LED light directly into the power grid, unless solar or mechanical (hand-crank, hydro, wind, etc) energy is being used to recharge them.
The above analysis leads to only one conclusion: apart from solar (stored in a deep cycle battery) or mechanical sources, if you want to celebrate Earth Hour with light it’s more eco-friendly to plug an LED into the grid. Otherwise, you’re better off passing the hour in darkness.