Storage
To resolve intermittency issues, several storage technologies are being investigated: mechanical, chemical and electromagnet. So far, large scale, low cost storage technologies with a fast response rate are not commercially available.
Capacity credit
Wind cannot be turned on at will, so it is not dispatchable. The relatively low capacity credit of wind power, which becomes lower as the amount of installed wind power capacity increases, has raised questions about the actual economics of wind energy. Various reports have shown capacity credits as low as 4% to 15%. More independent study and evidence of this is needed.
Mis-match of supply and demand
It is not the case in all countries but there have been reports that for meteorological reasons maximum generation can take place at times of minimum demand, due to weather patterns. This has happened in Denmark, occasioning large exports to Norway and Sweden, at a financial loss to the Danish consumer. In the UK, which has the highest wind resources in Europe, it is claimed that this is not an issue.
Load following
The ability of wind generators to respond to changes in demand is an issue. Wind cannot contribute to load following requirements due to its intermittent or variable nature which makes it impossible to operate incrementally over time. This is because unlike energy sources like fossil fuel, wind turbines cannot be ramped up or down to meet instantaneous load changes.
Dispersion
Many studies have shown that wind turbines must be widely dispersed to avoid large numbers of them being affected by the same weather patterns at the same time, thus reducing the impact of variability.
Inadequacy of weather forecasting
There have been many accounts, well documented in the E.ON reports, of inaccurate weather forecasting, which has impacted on the ability of the networks to balance their systems.
