The idea of “We’re moving in the right direction, but we’re not moving fast enough” is commonly heard when discussing our current situation with the effort to counteract climate change and the rise of the Green New Deal (GND) and the Sunrise Movement. But how do we know we are moving in the right direction? What would “moving fast enough” look like? It helps to have some quantitative benchmarks and milestones on the road to the post-carbon economy. I will discuss two measures in this article, “peak carbon” and the “target-to-actual ratio.” (All my data come from the U.S. Energy Information Administration website.)
“Peak carbon” is the historical high-water mark for annual greenhouse gas emissions, after which the quantity declines as we move away from carbon; it is also the peak year. If you want to eventually get to zero carbon, you first need to turn a corner and start moving in the right direction. U.S. CO2 emissions fell from 6 to 5.1 gigatonnes of CO2 per year between 2007 and 2017, so hopefully 6 Gt in 2007 represents the U.S. peak carbon point. Unfortunately, emissions started rising again in 2018. As a bare minimum objective, to make peak carbon in 2007 “stick,” we need to prevent a return to 6 Gt and continue to drive emissions lower.
To address climate change, achieving global peak carbon is what really matters. World CO2 has not reached peak carbon yet. As a first baby step, CO2 emissions stayed on a plateau around 35 Gt between 2013 and 2016. From 2017 on, they continued rising. Having individual countries pursue national peak carbon is a way to slow this trend. The problem is that, if some countries reach peak carbon and others do not, it will be very hard to reduce overall world emissions. Therefore, we need to add a step to the GND. We not only need to reduce our own emissions as a community, as the state of New York or as a country. We need to use our example to strongly encourage and challenge our peers to do the same. We could expect that they will bring the same pressure to bear on us.
The need for faster emissions reduction brings up the second metric, namely the target-to-actual ratio for energy transition. It is the ratio of how fast we need to move to reach a future target to the rate at which we are actually moving. To create an example, I will go back to the year 2016 so that I have full data about the U.S. energy market available.
Suppose we start in the year 2016 with the objective of phasing out electricity from fossil fuels by 2030, as in the GND. Total electricity consumption in the U.S. has hovered around 4 trillion kWh per year since 2005, so let us assume that it stays at this amount through 2030. Of the total, about 2.6 trillion kWh came from natural gas and coal and a small contribution from fuel oil. With 14 years until 2030, you would need to add new renewable generation equivalent to 186 billion kWh/year to meet the target.
The actual increase in solar and wind for 2016-17 was around 50 billion kWh. Therefore, the ratio value is 3.7, meaning that we need to be moving 3.7 times as fast to hit the GND target. You could also flip the metric around and treat the actual rate as a percentage of what we need to achieve. If a 100% score represents being on track to meet the GND target, then we are at a score of 27% by this calculation.
To conclude, I offer two observations about the metrics. First, the target-to-actual ratio backs up and quantifies the intuition at the beginning: We are indeed moving too slowly. In the year 2019, this is a sobering assessment, especially since it does not take into account the transition in liquid fuels for transportation or use of natural gas for heating and industry, where things are moving even more slowly.
In addition, in the past five years, the rate of solar panel installation has been growing, but the rate of wind installation has actually slowed. The U.S. wind industry had its best years in 2009 and 2012 in terms of new installations, and no year since then has been as good.
Second, and on a more positive note, the target-to-actual ratio can empower us going forward. Armed with this metric, we can redouble our efforts as individuals and communities to increase our use of renewable energy. We can also lobby our political leaders to implement policies that make the transition go faster.
After all, many of these leaders are already on board with accelerating the change, whether through the GND, renewable portfolio standards, the Energy Innovation and Carbon Dividend Act or some other mechanism. Whatever the policy, we should be able to get on track to phase in renewables at a sufficient rate. Once we get on track, we can make sure we stay there. Eventually, if the U.S. joins with enough other countries and all start moving fast enough, we should reach global peak carbon – the sooner, the better.
Francis Vanek is a Senior Lecturer in Civil & Environmental Engineering at Cornell University. He is lead author of the textbook “Energy Systems Engineering: Evaluation and Implementation (3rd Edition)”, published by McGraw-Hill in 2016.
This is a rock solid starting point for all of us. Thank you Dr. Vanek!
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