I finished up UNC’s 2009 greenhouse gas inventory last month, and I’m pleased to say we had our first year of reduction since I started my job.  Better yet, it was a big reduction: 20% lower than 2008.

Part of that reduction was due to some improved nitrous oxide emission factors for our coal boilers.  It turns out we had been overestimating our emissions over the past few years due to some old data and emission factors from the EPA.  The new factors are something like two orders of magnitude lower than previous estimates.  That shaved about 50,000 tons off of our carbon footprint.

The other major part of our reduction can be attributed directly or indirectly to 2009′s bad economy. A weak industrial sector and reduced energy demand made natural gas less expensive than coal for a few months.  At about half the carbon emissions per unit of heat, burning gas is one strategy for carbon reduction.  Electricity demand was also lower, meaning our regional utility, Duke Energy, produced a greater proportion of its electricity with its base load nuclear plants.  More carbon free kilowatts meant the emission intensity of grid was at its lowest since 1993.  The University bought more power than ever in 2009, but our emissions due to purchased electricity went down.  Weird.

A bad economy meant budget cuts, and the University pursued an energy efficiency program in all of its buildings as a way to cut costs and carbon.  After about 12 months and an investment of just $200,000, the University saved about $4 million and 40,000 tons of CO2.  Now THAT’s an investment!

You can read the full report here.