Waste—the final frontier

SOAPBOX: "Wasted Energy," by Hannah Fairfield, New York Times, 1 June 2008, p. BU6.

We create about 40 quadrillion BTUs of energy in the U.S. each year, but only about 33% is actually consumed by end users (14 quad). The rest is lost to conversion (27 quads) and distribution (1-plus quads).

Current conversion technologies thus mean we lose almost two-thirds of our energy that way.

Just on the immediate horizon, though, are technologies that should boost the capture to more like 50%.

Environmentalism of the future will be more Amory Lovins-style: more efficiency focused than pollution obsessed. Master the first and the second falls into place.

Comments

[David Stewart]

Thermodynamics is the key issue here. The max conversion efficiency for any method that converts heat to another kind of energy is (1-T(lo)/T(hi)) where T(hi) is the highest temperature in the system (in absolute degrees) and T(lo) is the lowest temperature in the system. For most power plants, T(hi) is constrained by the structural properties of steel, while T(lo) is the outside air temperature. This means that our max conversion efficiency via heat is going to be about 35% in practice. We can actually get pretty close to that in most current power plants. To get better requires direct conversion methods, such as you find in fuel cells (chemical nergy -> electricity), which are aiming at about 50%. 50% is about the conversion efficiency of photosynthesis (light -> chemical energy). Solar cells have been running about 25% to 30% efficiency (light -> electricity), for the best. (Most commercial solar cells are at about 15% to 20%.)

The waste heat from any themal based power plant (coal, oil, nuclear, ethanol, etc.) can be used --- it is still heat energy. The difficulty is piping it to somewhere where it can do some good. This is called co-generation or combined heat and power (CHP) generation. Some power plants actually do this.

[stuart abrams]

I read that Denmark currently satisfies 55% of its energy needs through cogeneration and recovery of energy waste. The US is way behind. There's good money to be made here.

[Brian H]

I have hopes that FocusFusion.org will pull it off in 5-8 years. It uses no thermal conversion at all, just an ion stream down a solenoid coil and a patented multi-thousand-metal-foil-layer onionskin containment to bleed virtually all power out of escaping X-rays. The net efficiencies are in the 85-95% range.

The cost advantage is huge, of course. Output would cost less than 0.2¢/kwh at source.

[Michael]

Transmission efficiency also has to be considered, both for the power lost and for the limits it puts on the radius of usage around the power plant.

One idea that's been bandied about at least since the '70s is orbital power transmission. Works the same way as satellite communications, except the microwave beams are much higher powered. Given sufficient capacity, such a system would allow:*a global energy grid, instead of the regional or continental grids we have now*easier access to otherwise remote power sources or customers*easier construction of a space-based solar power system (your transmission network is already there).