Many utility cooperatives strive to bring the best service at the lowest possible cost, but often the high cost of maintaining the infrastructure needed to cover large, rural areas without the support of large cities as a rich customer base causes prices to be high. However, a few such co-ops have managed to tap into urban markets (due to growth into previously rural territory served by the co-ops) and have proven to be very cost-effective. More recently established energy co-ops began with national coverage: Co-operative Energy in the UK and Enercoop in France are examples of consumer cooperatives. Other co-ops have formed to concentrate on the generation of renewable energy, especially wind energy co-operatives.