The Answer, My Friend is Blowing in the Wind…
With oil prices and climate change consistently in the news, there can be no doubt: we are facing an energy problem to be reckoned with for the long run. Experts agree that both energy efficiency and carbon-free, renewable resources must form the basis of any sustainable energy strategy for the future. A big part of this solution is indeed blowing in the wind.
The idea of wind power isn’t new. Mechanical wind and watermills have been used to grind grains between large, rotating millstones for many centuries, with the earliest machines dating back to around 200 BC in Persia and to ancient Greece. Thus, when electricity arrived in the early 1900s, it was only natural to look to wind and water for the power to rotate electric generators.
Since that time, hydroelectricity has had a steady presence throughout the world. Because water running downhill carries much weight at high speed, the mechanical energy is very concentrated. Consequently, hydropower is inexpensive – assuming a convenient location can be found for capturing the fast-moving water, and for storing it behind a dam. Dams offer the convenience of getting our energy whenever we want it, not just after the rains. But because such sites are limited, and due to the serious environmental impacts of creating reservoirs, hydropower cannot be exploited in arbitrary amounts.
A variation on this theme is tidal power, where underwater turbines are driven not by a river but the flow of ocean water into and out of tidal basins. Again, the key constraint is location. In the San Francisco Bay, for example, there seems to be a considerable tidal flow, but it is mostly near the surface, and the energy that is practical to extract turns out to be less than one might hope.
Unlike water, wind is accessible in many places. To be sure, microclimates vary, and Sonoma County, for example, has only a few local pockets of the consistent wind speeds needed to produce electricity economically. Throughout California, though, the energy from high wind areas such as the Altamont, Tehachapi and San Gorgonio Passes adds up to a respectable amount – about 2.3 percent of the State’s electricity in 2007 came from wind, and the number is growing with new installations nearly every day. Across the United States, last year there was a record of 46% growth in wind energy, with 5,329 new megawatts installed and $9 billion of investment.
Because air is less dense than water, wind turbines are bigger and take up more acreage. Moreover, you can’t store the wind for when the power is needed, and many of the technical challenges in turbine and power system design have to do with the wind’s variability over time – how to adapt the machine to most efficiently extract power under different conditions, and not break apart in a storm. But engineers have been improving upon these designs for many years.
Indeed, the first wind turbines went online in the early 1900s, and local wind power competed with the federally subsidized grid for rural electrification in the 1930s. With fossil fuels abundant and cheap – and their inherent problems not yet obvious – renewable resources were easy to ignore. Yet today, wind is being rediscovered as the least-cost energy source in many locations – second only to reducing energy demand through efficiency. In California, at least, we’ve shown that we can do both!