To the Editor:

I thought it would be helpful to respond to Lillian Lake’s column regarding the downside of photovoltaic panels.  Any reader who has followed our Franklin Journal column “Energy Matters” will know that when it comes to energy matters we are always trying to address the question of “how much?” In other words it is unhelpful to say something is good or bad without quantifying it and balancing it against other considerations.

Lillian talks for example about the fact that sulfur hexafluoride (SF6) is a terrible greenhouse gas and that it is associated with solar panels, but she doesn’t point out that the amount released worldwide is tiny. It is true that a molecule of SF6 does have 23,500 times the warming potential of a CO2 molecule.  But, due its much higher concentration – 41 million times higher – in the atmosphere, the net warming of CO2 is more than 1700 times that of SF6.

Additionally there are relatively straightforward technological ways to reduce SF6 emission in the future, while trying to capture CO2 at scale is proving to be a difficult and energy intensive process. Incidentally only about 7% of the SF6 is associated with solar panel manufacture, most of the rest is used in other electrical components.  There is no SF6 in the panels themselves.

Another point from Lillian’s column I’d like to address is that of the waste stream from photovoltaics. Again, saying something is “a lot” without a comparison can be misleading.  While I completely agree that including the cost of disposal and recycling is crucial to successful deployment of renewable energy we must compare it to the cost of business as usual. A solar panel rated at 1000 watts here in Maine will produce roughly 44,000 kWh of electricity over its 30 year lifetime.

Its total weight is under 150 lbs, 80% of which is glass and aluminum, which are easily separated and recycled or reused, leaving 30 lbs of more difficult, but mostly recyclable material. Over its life cycle (manufacture, use, and disposal) the panel will be responsible for around 1000 lbs of CO2 (mostly in the manufacturing process.)

To produce that much electrical energy from coal would require about 35,000 lbs of coal; from oil about 5,000 gallons.  The waste from the coal would be between 2000 and 9000 lbs of toxic coal ash and almost 90,000 lbs of CO2. It is also the largest producer of atmospheric mercury pollution in the US. Neither the coal industry nor the electric power industry pay for CO2 disposal. While coal ash is presumably taken care of by the energy companies, there have been very significant spills in the past. It is the second largest source of solid waste after household trash.

So how would you choose: 30 lbs of waste plus 1000 lbs of CO2… or 5000 lbs of coal ash plus 90,000 lbs of CO2 to get the same amount of electricity?