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kristopher Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Dec-07-08 04:52 PM
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19. Here is the relevant section; have at it...
4b. Carbon emissions due to opportunity cost from planning-to-operation delays

The investment in an energy technology with a long time between planning and operation increases carbon dioxide and air pollutant emissions relative to a technology with a short time between planning and operation. This occurs because the delay permits the longer operation of higher-carbon emitting existing power generation, such as natural gas peaker plants or coal-fired power plants, until their replacement occurs. In other words, the delay results in an opportunity cost in terms of climate- and air-pollution-relevant emissions. In the future, the power mix will likely become cleaner; thus, the opportunity-cost emissions will probably decrease over the long term. Ideally, we would model such changes over time. However, given that fossil-power construction continues to increase worldwide simultaneously with expansion of cleaner energy sources and the uncertainty of the rate of change, we estimate such emissions based on the current power mix.

The time between planning and operation of a technology includes the time to site, finance, permit, insure, construct, license, and connect the technology to the utility grid.

The time between planning and operation of a nuclear power plant includes the time to obtain a site and construction permit, the time between construction permit approval and issue, and the construction time of the plant. In March, 2007, the U.S. Nuclear Regulatory Commission approved the first request for a site permit in 30 yr. This process took 3.5 yr. The time to review and approve a construction permit is another 2 yr and the time between the construction permit approval and issue is about 0.5 yr. Thus, the minimum time for preconstruction approvals (and financing) is 6 yr. We estimate the maximum time as 10 yr. The time to construct a nuclear reactor depends significantly on regulatory requirements and costs. Because of inflation in the 1970s and more stringent safety regulation on nuclear power plants placed shortly before and after the Three-Mile Island accident in 1979, US nuclear plant construction times increased from around 7 yr in 1971 to 12 yr in 1980.63 The median construction time for reactors in the US built since 1970 is 9 yr.64 US regulations have been streamlined somewhat, and nuclear power plant developers suggest that construction costs are now lower and construction times shorter than they have been historically. However, projected costs for new nuclear reactors have historically been underestimated64 and construction costs of all new energy facilities have recently risen. Nevertheless, based on the most optimistic future projections of nuclear power construction times of 45 yr65 and those times based on historic data,64 we assume future construction times due to nuclear power plants as 49 yr. Thus, the overall time between planning and operation of a nuclear power plant ranges from 1019 yr.

The time between planning and operation of a wind farm includes a development and construction period. The development period, which includes the time required to identify a site, purchase or lease the land, monitor winds, install transmission, negotiate a power-purchase agreement, and obtain permits, can take from 0.55 yr, with more typical times from 13 yr. The construction period for a small to medium wind farm (15 MW or less) is 1 year and for a large farm is 12 yr.66 Thus, the overall time between planning and operation of a large wind farm is 25 yr.

For geothermal power, the development time can, in extreme cases, take over a decade but with an average time of 2 yr.27 We use a range of 13 yr. Construction times for a cluster of geothermal plants of 250 MW or more are at least 2 yr.67 We use a range of 23 yr. Thus, the total planning-to-operation time for a large geothermal power plant is 36 yr.

For CSP, the construction time is similar to that of a wind farm. For example, Nevada Solar One required about 1.5 yr for construction. Similarly, an ethanol refinery requires about 1.5 yr to construct. We assume a range in both cases of 12 yr. We also assume the development time is the same as that for a wind farm, 13 yr. Thus, the overall planning-to-operation time for a CSP plant or ethanol refinery is 25 yr. We assume the same time range for tidal, wave, and solar-PV power plants.

The time to plan and construct a coal-fired power plant without CCS equipment is generally 58 yr. CCS technology would be added during this period. The development time is another 13 yr. Thus, the total planning-to-operation time for a standard coal plant with CCS is estimated to be 611 yr. If the coal-CCS plant is an IGCC plant, the time may be longer since none has been built to date.

Dams with hydroelectric power plants have varying construction times. Aswan Dam required 13 yr (18891902). Hoover Dam required 4 yr (1931 to 1935). Shasta Dam required 7 yr (19381945). Glen Canyon Dam required 10 yr (1956 to 1966). Gardiner Dam required 8 yr (19591967). Construction on Three Gorges Dam in China began on December 14, 1994 and is expected to be fully operation only in 2011, after 15 yr. Plans for the dam were submitted in the 1980s. Here, we assume a normal range of construction periods of 612 yr and a development period of 24 yr for a total planning-to-operation period of 816 yr.

We assume that after the first lifetime of any plant, the plant is refurbished or retrofitted, requiring a downtime of 24 yr for nuclear, 23 yr for coal-CCS, and 12 yr for all other technologies. We then calculate the CO2e emissions per kWh due to the total downtime for each technology over 100 yr of operation assuming emissions during downtime will be the average current emission of the power sector. Finally, we subtract such emissions for each technology from that of the technology with the least emissions to obtain the opportunity-cost CO2e emissions for the technology. The opportunity-cost emissions of the least-emitting technology is, by definition, zero. Solar-PV, CSP, and wind all had the lowest CO2e emissions due to planning-to-operation time, so any could be used to determine the opportunity cost of the other technologies.

We perform this analysis for only the electricity-generating technologies. For corn and cellulosic ethanol the CO2e emissions are already equal to or greater than those of gasoline, so the downtime of an ethanol refinery is unlikely to increase CO2e emissions relative to current transportation emissions.

Results of this analysis are summarized in Table 3. For solar-PV, CSP, and wind, the opportunity cost was zero since these all had the lowest CO2e emissions due to delays. Wave and tidal had an opportunity cost only because the lifetimes of these technologies are shorter than those of the other technologies due to the harsh conditions of being on the surface or under ocean water, so replacing wave and tidal devices will occur more frequently than replacing the other devices, increasing down time of the former. Although hydroelectric power plants have very long lifetimes, the time between their planning and initial operation is substantial, causing high opportunity cost CO2e emissions for them. The same problem arises with nuclear and coal-CCS plants. For nuclear, the opportunity CO2e is much larger than the lifecycle CO2e. Coal-CCS's opportunity-cost CO2e is much smaller than its lifecycle CO2e. In sum, the technologies that have moderate to long lifetimes and that can be planned and installed quickly are those with the lowest opportunity cost CO2e emissions.
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