We all know we need to get off fossil fuels and replace them with carbon-neutral alternatives. The question is not IF we should choose this path, but how best to get where we need to go. There are those who, fairly enough, worry that those clean renewables aren’t up to the job. This is a critical question, because if renewables can’t fill the void, then we are left with no option but to build more nuclear reactors, with all the myriad problems that accompany them, most notably price, which is forever rising. So much money is at stake that we need to sort out this question, soon.
It all boils down to power demand. How much power do we need? If the number is such that the most realistically rapid installation rate of new wind, water and solar power supplies won’t be enough to satisfy our needs in say, 2030 (by which time we need to have at least made a sizable dent in replacing the existing oil, gas and coal plants), then we have a problem. So what is a reasonable projection of power demand in 2030?
Unfortunately, that depends on whom you ask. Even estimates of current power consumption vary widely For example, over at Yale’s e360, David Biello turns to MacArthur fellow Saul Griffith for a scenario that assumes
.. the U.S. will require roughly 4 terrawatts of power by 2050 (a conservative estimate, given that we already use more than three)…
You can find similar projections all over the place. But two other analysts, Mark Jacobson and Mark Delucchi, who survey the issue in some detail in a pair of papers discussed here, say current U.S. end use is only 2.5 TW, significantly less than 3 TW, not more. The higher figure is what we produce, the lower is what we use. The difference is lost during transmission and distribution, and to wasted heat. (Current end use figures, which are based on the U.S. Energy Information Administration data don’t appear in the Jacobson-Delucchi papers, but they are available at Jacobson’s website here in an Excel spreadsheet.)
Furthermore, because most electric power options are more efficient than those based on the internal combustion engine, and efficiency is expected to improve across the board in the coming years, they expect U.S. demand to be only 1.78 TW in 2030 if we convert all fossil fuels to wind, water and solar. And make sure we tighten up on the transmission and distribution losses, both of which will be significantly lower if power generation is decentralized and produced closer to where it’s used.
Jacobson and Delucchi write in Part 1 of their two-part paper that
… the direct use of electricity, for example, for heating or electric motors, is considerably more efficient than is fuel combustion in the same application. The use of electrolytic hydrogen is less efficient than is the use of fossil fuels for direct heating but more efficient for transportation when fuel cells are used; the efficiency difference between direct use of electricity and electrolytic hydrogen is due to the energy losses of electrolysis, and in the case of most transportation uses, the energy requirements of compression and the greater inefficiencies of fuel cells than batteries. Assuming that some additional modest energy-conservation measures are implemented (see the list of demand-side conservation measures in Section 2) and subtracting the energy requirements of petroleum refining, we estimate that an all-WWS world would require ~30% less end-use power than the EIA projects for the conventional fossil-fuel scenario.
What about 2050? Well, it’s reasonable to assume that by 2030 the U.S. as a whole would have learned how to do what California has done for the past 30 years — keep power demand growth near a flat line even while GDP expands greatly. So by mid-century, power demand likely won’t be much more than 1.78 TW. Let’s say 2 TW to be conservative. That’s only half of what Griffith estimates — quite a difference, almost certainly more than enough to change the answer to the question at hand.
Global use and demand trends are comparable in the Jacobson-Delucchi vision. This might be debatable, in that what is possible for the U.S. may not be as likely to occur in developing nations. But one can make good arguments that developing nations are actually more likely to embrace efficient technologies than countries where existing fossil-fuel power plants still have decades top run before they’re paid off.
This discussion will be familiar to advocates of rapid deployment of renewables. Say, as most climatologists who have studied the problem insist, we need to cut our emissions of greenhouse gases by 80-90& over the new three or four decades to avoid irrevocable and/or catastrophic global warming. That sounds daunting. But if we can cut demand in half through improvements to the efficiency of existing infrastructure, introduction of new technologies that are more inherently more efficient, and stop wasting so much heat and energy in the first place by making some strategic changes to how we work and get around, the task isn’t quite so daunting after all.
Building enough wind turbines and solar PV arrays to replace 85% of our energy mix will be difficult. Building enough wind, solar thermal and PV, geothermal, small-scale hydro and tidal generators to replace 42% sounds doable. And just so Griffith isn’t cast as the villain here, I’ll give the last word to one of his less pessimistic observations:
If society’s efforts were turned in different directions, shifting from making fewer consumer products to making more devices to capture renewable energy, the transition might ultimately fuel itself. After all, beverage makers now produce some 300 billion aluminum cans per year, Griffiths notes, which is enough production capacity to manufacture 100 or 200 gigawatts of solar thermal annually. “So we could do 1 terrawatt of solar in 10 years if Pepsi and Coca-Cola and all the breweries became solar companies,” he says. “We have the industrial scale. We are just right now prioritizing what we want to make with it and we are making disposable aluminum cans instead of solar mirrors. That gives me reason for optimism. We can do it.