This paper investigates the impact of the passage of Colorado's expanded Renewable Energy Standard (RES) on the state's energy and generation capacity needs. In September 2006, the Colorado Energy Forum (CEF) issued a report which found that, in order to reliably meet Colorado's anticipated customer electricity needs, 4,900 MW of new electric capacity is required by 2025.

In this paper, we estimate that, based on reasonable assumptions, over 3,300 MW of wind generation and nearly 200 MW of solar generation must be deployed in order to meet Colorado's RES. However, when taking into account the intermittent nature of wind and solar resources, we estimate that the reliable capacity credit for these renewable resources range between 330 MW and 1,122 MW. This means that even after the requirements of Colorado's RES are met, significant amounts of new electric capacity will still be required to meet the state's needs. Based on the assumptions and data in this study, Colorado will need to address additional resource needs in the range of 3,700 MW to 4,500 MW by 2025.

The CEF takes no position on how new resource needs should be met but believes it is important to understand the effects of the RES in the context of the state's overall future electricity requirements. The CEF expects that these requirements will be met through a combination of increased energy efficiency, renewable resources, emerging generation technologies and conventional generating resources.

There will be a continuing need for energy infrastructure investment. The state will need to build more power plants, even after considering the expanded role of renewable resources and after deploying energy conservation resources. Hundreds of miles of additional transmission lines will need to be built to ensure reliability. CEF previously reported the consequences of failure to meet the identified resource need. Higher electricity rates could make the Colorado economy less competitive, and if the state's utilities are not able to meet the expected growth in future demand, reliability will be decreased, with a huge financial cost to Colorado.