Avoid carbon dioxide emissions: Doing the math on green power
If we can avoid burning fossil fuels to make electricity (or heat our homes), we can avoid carbon dioxide emissions which cause global warming. Fortunately, we can do just that by buying green power and making our homes energy efficient. Can we quantify the benefits of green power and efficiency? Yes, we can! Here’s how:
The organization that runs the New England power grid does an annual assessment of air emissions made by generators in the region. The assessment reports on how much sulfur dioxide, nitrogen dioxide, and carbon dioxide are emitted in a given year, both on average per megawatt hour and at the margin. By “at the margin” we mean the last megawatt hour (MWh) produced. When we consider how avoiding emissions is a benefit, we calculate the benefit by looking at the marginal rate, which is the rate associated with the last megawatt hour we are using on the New England Power grid. For those of who are concerned about climate change, we are interested in the marginal rate of carbon dioxide emissions because we want to replace that last megawatt hour of dirty energy with something that is zero-emission. The point is that that we claim credit for avoiding the marginal rate rather than the average rate.