Land rationalization has always been a significant issue regarding wind farms and wind power in general. In fact, large-scale wind energy plants occupy even several dozens square kilometres.
This is because conventional (horizontal-axis) wind turbines must be spaced at a considerable distance from each other, since turbulences created by one turbine greatly reduce the efficiency of the others that are placed behind it or next to it.
This is why wind turbines are usually installed horizontally, though this configuration greatly increases the visual impact and may cause opposition from local communities.
Instead, Californian scientists believe that vertical-axis wind turbines could be bunched up.
According to the mathematical models used for the study, vertical-axis wind turbines can benefit from a more compact geometrical arrangements: indeed, rotors placed behind a leading turbine seem to function more efficiently when their rotational direction is alternated.
The best course of action is to have a leading turbine which – for instance – rotates clockwise, with two turbines behind it that rotate anticlockwise, and then behind them an array of three turbines again rotating anticlockwise, and so on.
These conclusions are still preliminary and need to be confirmed, warn the Pasadena researchers, but though they expect tangible results to come about soon. They also noted that even if the configuration of these turbines would achieve only 50% of land-use gain, compared to current ones, it would still be a major improvement.
Also, vertical-axis wind turbines could have a reduced impact on flying birds. In fact, when they spin, they appear solid, allowing migrant birds to avoid them more easily than horizontal-axis turbines, which become almost invisible when they spin fast.