CO2, Oil, Electric Vehicles, Wind and Solar

We know that for some amount of money we could change from an oil-dependent society spewing CO2 to one that is self-sufficient and not damaging our world. The technology for doing so exists, and improvements are occurring quickly.

Besides electric vehicles, wind and solar, there are other potential contributors to this transition, but they are each relatively small. You can save just so much energy without turning yourself into a primitive society. Biomass can provide back-up power and portable fuel. Geothermal, ground-source heat pumps, solar hot water heaters, and wave power can add to our diverse portfolio. But the bulk of new energy is most likely to come from the two most powerful sources, wind and solar. And biomass is never going to supply enough portable fuel to be of significance.

Wind and solar’s competitive characteristics are:

• Wind:
  • Advantages
    • Cheap in windy places – about 4-8 c/kWh (without transmission costs)
    • Located within a thousand miles, and usually half that, of most demand
    • Large enough to supply almost all world energy demand and second only to solar in size
    • Under-exploited offshore wind more dependable than on-shore wind, but more expensive (50%?)
  • Disadvantages
    • Blows 50% or more at night, sometimes much more (when electricity is less needed)
    • Blows more in winter than summer, missing some peak demand
    • More variable than solar annually, seasonally, and for most time intervals
    • Very sensitive to local wind speed, so locations almost always require some transmission
    • Unsightly towers can be seen from a distance; often located in visually appealing places due to correlation of terrain to wind speed
    • Carries tangible operating costs and turbines must be replaced about every 20 years
• Solar PV
  • Advantages
    • Largest potential source of renewable electricity on Earth; dwarfs second largest (wind) and all others > 100
    • Can be harnessed most places, but is cheapest where there is the most sun (linear relation to sunlight)
    • Rapidly dropping in cost, so that the cheapest systems are about 15 c/kWh or less; and future systems will approximate 8-10 c/kWh in the sunniest locations
    • Value of daytime electricity, and electricity supplied for summer peaks is much higher (even double) value of nighttime electricity from wind
    • Lasts over 30 years with minimal losses, and may last 100 if built to last that long;
    • Near-zero operating costs
    • Can be built in months rather than years
  • Disadvantages
    • Cost is about double wind and may only reach levels that are similar to wind in the sunniest locations
    • Output varies by season, and during the day as well due to clouds
    • In some circumstances for systems under 30 MW in size, variation from cloud movement can be quite abrupt (variation for large systems over 100 MW in size is much smoother and smaller in magnitude)
    • Use of the best solar locations (e.g., US Southwest) usually means that transmission will be needed
• Solar Thermal Electric
  • Advantages
    • May be built with relatively economical, on-site thermal storage, smoothing and extending output
    • Simpler technology than PV (boilers, mirrors, no semiconductors)
  • Disadvantages
    • Uses water for cooling, or else costs 10% or so more if uses air cooling
    • Can only be economical in near-perfect cloudless sunlight like deserts
    • Must be built in relatively large systems
    • Takes several years to build
    • Cost reduction potential unclear
    • More O&M than PV (more like wind)

There are parallel solutions to the variability of both wind and solar. They are:

1. Using existing natural gas turbines to back them up when their resources are absent;
2. Creating smarter and more responsive “balancing regions” that include solar and wind and their compensating gas turbines to smooth output to a reliable level;
3. Developing some storage to further compensate as solar and wind deployment becomes large enough to need it.

Many studies suggest that the near-term cost of solar or wind variability is about 1 c/kWh or less – not a major factor. This will be true for about the next twenty years or until they are deployed at greater than about 30% of our electricity. This is a lot of electricity, especially if we start using it for electric vehicles – enough to power all our light duty vehicles instead of gasoline.

We can avoid most CO2 and remove our dependence on foreign oil with solar, wind, smarter balancing regions with responsive natural gas turbines, and electrification of our transport – with what we have now and improvements already in the pipeline.

In the next blog, I’ll examine how much it might cost, and what an affordable but still effective strategy to do it might be.

And we can address the “deniers,” who really are saying, “Sure, we’d love to do this, but it would cost too much.” Because who wouldn’t want to do it, if it didn’t cost too much?

Ken Zweibel