Debate regarding wind power has centred on a number of issues. The body of evidence is accumulating, revealing problems and solutions are being proposed, but some of these issues still require much further study and analysis.
It should be emphasised that it is not within the scope of this report to present a full summary of all the evidence, arguments and conclusions in these matters. The purpose is to raise the issues and to point out that questions exist. Some of these questions have been answered, others remain to be answered.
In order to maintain security of supply, a second-by-second balance between generation and demand must be achieved. An excess of generation causes the system frequency to rise whilst an excess of demand causes it to fall. To sustain the balance, the electric system must provide power at the instant the load demands it, and at the prescribed frequency and voltage limits. Variations outside these limits can either cause protective systems to shut down large parts of the network or can cause extensive damage to delivery equipment and customers’ facilities. This is a vital issue for intermittent sources of energy.
Network balancing problems have occurred because of the variability of wind power and these have sometimes been serious. It has been pointed out that this is the normal state of an electrical system and a wholly fossil fuel powered system requires a spinning reserve in any case. However, evidence suggests that wind power can exacerbate this problem.
Because in many countries wind turbines are sited in remote areas where wind speeds are high but the distance from load centres is considerable, the transmission of large amounts of energy has placed burdens on the transmission system and caused congestion. This has been acute in Germany where the main fossil fuel base load generators are located in industrial areas, requiring little transmission capacity and the transmission network has developed accordingly. It will also need to be addressed in the UK where offshore wind farm developments in the northwest of Scotland will place burdens on the transmission network to transport power south. Because wind proposals have not always come to fruition, National Grid at one time proposed requiring a deposit from wind developers to link them to the grid.
The effects of sudden and intermittent flows of electricity reach beyond the location of the wind generators, unless they are in an electrical island. Examples of this are found in Poland and the Slovak Republic. The Polish TSO, Polskie Sieci Elektroenergetyczne SA has stated that it will need to make new investment in transmission capacity to accommodate the additional power from Germany. Likewise the Slovak TSO, SEPS, Slovenska elektrizacna prenosova sustava, has told ABS that they will need to construct major new interconnection capacity with the Czech Republic to accommodate the surges of wind power flowing south from Germany.