This Sunday marks the 38th annual observance of Earth Day since its beginning in 1970. Rather than focus on this year's event, I started thinking about what the fiftieth anniversary of Earth Day in 2020 might look like. The focus today is on the tough challenges ahead. But considering the rate at which global interest in climate change is coalescing, much as concern for air and water pollution did in the 1960s and 70s, we ought to see great progress in reducing emissions by then. Or will we? We're pushing against an energy system with enormous inertia, and that still hasn't stopped growing. How different might the environmental impact of our energy systems be on Earth Day plus Fifty?
Consider some extrapolations. If renewable energy were able to capture 50% of the projected annual increases in US electricity generation between now and 2020--which seems attainable, based on recent experience--then by the end of the next decade renewables including hydropower would have expanded from 9% of the mix to roughly 16%. That's impressive growth, though it would still put renewables behind nuclear power, which starts at 20% and is expected to decline slightly. Fossil fuel-based power would account for 65%, down from 71% now. However, even if renewables captured 100% of the growth in electricity generation between now and 2020, giving them a 25% share of the electricity market, the resulting mix would still emit as much greenhouse gas as today's.
Turning to fuels, US ethanol consumption has quadrupled in the last decade. If it could sustain that kind of growth--assuming it doesn't run into limitations on corn supply or other inputs and that current incentives are retained or expanded--ethanol would contribute 25 billion gallons per year of motor fuel in 2020. With gasoline consumption continuing to expand at 1%/year, there would be enough ethanol to allow every gallon of gas to contain 10% ethanol, while enabling E-85 to grow to 8% of the market, a bit less than the current share for premium or mid-grade unleaded. But even if most of the extra ethanol came from cellulosic sources, with minimal greenhouse gas emissions, our vehicles would emit more carbon dioxide in 2020 than they do today, because we'd be using at least as much "base" gasoline as we do now.
These examples suggest that, from a climate change perspective, it won't be sufficient just to make our energy mix greener, if it's still growing. And while the figures above must look pretty conservative to environmentalists and alternative energy boosters, I would wager they look quite optimistic to experienced industry professionals. I'm sure you could get the marketing departments of major oil companies pretty excited by telling them that there's a new product that could deliver sales volumes almost as large as premium unleaded in a decade, without stealing any of their current sales. But I'm not sure you could convince them that they can get there from here, or that there'd be a profit in it for them.
That doesn't mean I'm pessimistic about the next decade. The best bet for achieving real progress by Earth Day 2020 might be neither economic or regulatory, but demographic. By the fiftieth anniversary of the first Earth Day, the oldest Baby Boomers will be in their mid-70s, while the youngest of us, along with the oldest Gen-X'ers, will be eligible for early retirement. Today's college students will be in their early 30s, and the oldest cohorts of the Millennial Generation will be hitting their mid-career stride, approaching their peak earning years. If their collective attitude towards the environment is as different from that of the Boomers as ours was from our parents', and if that translates into different consumption and investment patterns, then by 2020 they should be having a dramatic impact on the way that America uses energy. That might just be enough to rein in the growth of emissions.