 no annual revenues. Fuel-supply risk. In systems where the demand for natural gas for space heating and for peak electricity generation coincide, gas supply for space heating will generally be given a higher priority. Thus there is a risk that fuel supply to gas-fired peaking plants could be interrupted or curtailed during cold periods. Regulatory risk. Because peaking plants are called into service when prices are highest, they are disproportionately exposed to the risk of government- imposed caps on electricity prices. Market reform is creating uncertainty about future investment in transmission and distribution networks as well. Transmission owners and operators have far less certainty about the demands that will be placed on their networks and, with the unbundling of vertically integrated utilities, less capacity to undertake integrated planning and development of transmission networks as INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 3. OUTLOOK FOR GLOBAL INVESTMENT IN ELECTRICITY INFRASTRUCTURE a whole. Transmission system operators' capacity to manage system balancing is thus greatly reduced, particularly within regional markets incorporating several owners and operators. At the same time, regulatory and policy uncertainty can heighten the business risks faced by transmission system owners, which can discourage investment. The situation can be further complicated by vested interests seeking to weaken incentives for efficient network performance, and by jurisdictional boundaries cutting across networks and interconnections. Large-scale blackouts occurred in 2003 and 2004 in a number of OECD countries, notably in North America, Italy, southern Sweden and eastern Denmark. These incidents raised concerns that the transmission infrastructure was inadequate and that major new investment in transmission capacity was needed to improve transmission system reliability. In each of these cases, official investigations concluded that the blackouts were not cause