The renewable obligation (RO) is the main support mechanism
for renewable electricity projects in the United Kingdom (UK).
Smaller scale generation is mainly supported through the Feed-in
Tariff scheme (FiT). The RO came into effect in 2002 in England and
Wales as well as Scotland and in 2005 in Northern Ireland [57]. It
places an obligation on electricity suppliers to source an increasing
proportion of the electricity they supply to customers from
renewable sources. This is done through purchasing a Renewable
Obligation Certificate (ROC) issued to an accredited generator for
renewable electricity. It is a proof that a certain amount of
electricity has been generated from an RE source.