Experiencing Technical Difficulties (resonant) wrote,
Experiencing Technical Difficulties
resonant

Wind power and solar power scale differently

elenbarathi brought up a good point in an earlier post. Solar panels make economic sense for small house-top installations. Solar panels also make economic sense for huge industrial solar farms. Why don't we see small wind turbines being installed on every house? Cities have lots of tall lampposts, why don't we stick little wind turbines on top of each one?

The reason is that costs scale weirdly with wind turbines.

Solar scales mostly linearly. A small panel on your roof creates nearly as much power per unit of invested resources as a huge solar farm in the desert. Wind scales geometrically; a single huge wind turbine makes thousands of times more power than using the same resources to make millions of little turbines.

If you make a solar panel twice as wide and long, it uses a bit less* than four times as much material, and costs a bit less than four times as much to build and install. The power generated is about four times as much as the original panel, as it is (nearly) directly proportional to the surface area.

If you make a wind turbine blade twice as long, it uses a bit more than twice as much material, and costs a bit more than twice as much to build and install. However, the power generated is FOUR times as much, as the area covered by the spinning blades is proportional to the square of the blade length.

If you make a tower twice as tall, so you get your blades into breezes that are steadier and that are twice as strong, it costs more than twice as much to build and install. However, the power generated is EIGHT times as much, as the power output is proportional to the cube of the wind velocity.

If you're building wind turbines, the way to get the most return on your investment of money and resources is to make them as big as technology allows.


* larger solar panels do require less extruded aluminum per cell for the side stiffeners, have less shading per cell from the side stiffeners, and require a bit less labour per cell to install, so small solar installations are at a slight disadvantage compared to larger ones.
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