Greenhouse gas emissions are an abstract concept for most people. Ask a sample of Canadians what Canada’s annual GHG emissions are, and you’ll likely get a very broad range of answers (they’re about 750 million metric tons (Mt) per year).
The figures are so abstract that errors like Gasland producer Josh Fox claiming that Canada’s oilsands emit 36 Mt of GHGs per day go unnoticed by many – likely because they don’t have the context to catch the mistake rather than because they don’t care about the exaggeration. If you’re one of those people who didn’t catch the error, 36 Mt per day is about half of the world’s total GHG emissions, while oilsands emissions are about 40 Mt per year.
I am guilty of this abstraction myself – I deal in megatons all the time, whether it’s talking about carbon capture and storage, oilsands, or just about anything else I do – and I don’t often stop to think about the scale of those numbers. I decided to do something about this, using the example of Keystone XL.
The Keystone XL pipeline has been the source of a great deal of controversy, much of it centered on how best to assess the net increase in GHG emissions from building a new pipeline to deliver oilsands crude to the Texas Gulf Coast. The US State Department puts the net impact at between 3 and 20 Mt per year. The EPA puts the number about 20% higher, while my own back-of-the-envelope calculations put the net impact at no more than 28 Mt per year.
Since climate change is a global problem, my first reflex is often to consider impacts in terms of percentage of global emissions. Global emissions are just about 30 billion metric tons, or 30,000 Mt, which means that the potential increase due to the Keystone XL pipeline ranges somewhere between one tenth and one hundredth of a percent – either way, it’s a small number on that scale.
What would happen if you brought those numbers closer to home – closer to units to which we can relate? To do this, I decided to think about home retrofits, and specifically the question of how many houses you would have to retrofit (over and above those which would be retrofitted anyway) in order to offset the net increase in GHGs due to Keystone XL.
Under the ecoEnergy Retrofit program, Canadian homeowners can apply for a reimbursement of some of the costs of energy-saving home improvements as long as they have an energy audit performed before undertaking the renovations. NRCan reports that the average audit recommended actions which would lead to predicted GHG reductions of 3t/yr. Since it is generally the case that realized energy savings don’t match predicted energy savings as a result of households taking on fewer renovations than recommended or increasing the use of more energy-efficient products (the rebound effect), let’s assume that each retrofit actually leads to savings of 2t/yr. Further, assume that those savings last for 15 years, by which time the house would have been retrofitted anyway. Under these simplifying assumptions (adjust as you see fit), each retrofit leads to 30t of cumulative emissions reductions. The estimates won’t be perfect, but the order of magnitude will be right. Now, let’s put those two numbers together.
Assuming the Keystone XL pipeline is in service for 50 years, and that the net GHG emissions impact is in the middle of the range given above (15 Mt/year), this implies that you would need to retrofit 500,000 homes per year on average over the lifetime of the pipeline to offset the impact – about one house per minute for 50 years.
Now, 500,000 home retrofits seems like a big number, but it needs some context too. The ecoEnergy Retrofit Program financed approximately 225,000 renovations in the 2010-2011 fiscal year, but it’s likely true that many of those retrofits would have occurred in the absence of the program – the so-called free riders on the subsidy. In order to generate 500,000 retrofits per year over-and-above those which would otherwise have occurred, the program would likely have to finance at least twice that many and probably more – likely a 5-fold expansion of the current program. Given the current program costs $400 million per year to run, you’d likely need an additional $2 billion in retrofit subsidies to offset the GHG impacts of the Keystone XL pipeline.
When you think of the impacts that way – in terms of one renovated 1960’s bungalow like my own every minute – it puts a whole new perspective on the scale.