Restricting nuclear power has little effect on the cost of climate policies

ScienceDaily (Oct. 1, 2012) — By applying a global energy-economy computer simulation that fully captures the competition between alternative power supply technologies, a team of scientists analyzed trade-offs between nuclear and climate policies. Strong greenhouse-gas emissions reduction to mitigate global warming shows to have much larger impact on economics than nuclear policy, according to the study. Incremental costs due to policy options restricting the use of nuclear power do not significantly increase the cost of even stringent greenhouse-gas emissions reductions.

"Questions have been raised if restricting nuclear energy -- an option considered by some countries after the accident in Fukushima, Japan -- combined with climate policies might get extremely expensive. Our study is a first assessment of the consequences of a broad range of combinations of climate and nuclear policies," lead author Nico Bauer says. Restrictions on nuclear power could be political decisions, but also regulations imposed by safety authorities. Power generation capacities would have to be replaced, but fossil fuels would become costly due to a price on CO2 emissions, this in sum is the main concern.

"However, in case of restricted use of nuclear power, the flexibility of allocating a long-term carbon budget over time enables higher near-term emissions due to increased power generation of natural gas," Bauer says. Along with demand reductions and efficiency improvements, these provisions could help fill the gap on electricity. The price of natural gas is projected to decrease due to demand reductions, according to the study. Decommissioning existing plants will also avoid refurbishment costs for expanding lifetimes of old nuclear power plants.

As a result, early retirement of nuclear power plants would lead to cumulative global gross domestic product losses (GDP) that amount to about 10 percent of climate policy costs. If no new nuclear capacities are allowed, the costs would amount to 20 percent.

For their study, the scientists looked into different nuclear power policies. These cover a range of scenarios from "Renaissance," with a full utilization of existing power plants, a possible refurbishment for a lifetime expansion and investments in new nuclear power capacities, to "Full exit," with a decommissioning of existing power plants and no new investments. They contrasted each scenario with climate policies implemented via an inter-temporal global carbon budget which puts a price on carbon emissions. For the budget, the cumulative CO2 emissions from the global energy sector were limited to 300 gigatons of carbon from 2005 until the end of the century. This represents a climate mitigation policy consistent with the target of limiting global warming to 2 degrees Celsius.

"A surprising result of our study is the rather little difference between a 'Renaissance' or a 'Full exit' of nuclear power in combination with a carbon budget when it comes to GDP losses," Bauer says. While the 'no policy case' with a nuclear phase-out and no carbon budget has only negligible effect on global GDP, the imposition of a carbon budget with no restrictions on nuclear policy implies a reduction of GDP that reaches 2.1 percent in 2050. The additional phase-out of nuclear power increases this loss by about 0.2 percent in 2050 and hence has only little additional impact on the economy, because the contribution of nuclear power to the electricity generation can be substituted relatively easy by alternative technology options, including the earlier deployment of renewables.

NREL Data Set Shows Clouds’ Effect on Solar Power System in 1-Second Intervals

Photo credit: Saving Oahu's Solar LLC

The US Dept. of Energy’s National Renewable Energy Laboratory (NREL) has produced and made publicly available a data set that shows in greater than ever detail the effect of clouds passing over a solar PV power installation. The data set captures second-by-second over the course of one year the effects of clouds passing over 17 measurement stations near Hawaii’s International Airport on Oahu.

The extremely granular nature of the data set can provide utilities, solar PV system operators and project developers, researchers, forecasters and others empirical data in heretofore unobtainable detail on the effects clouds have on the power output and overall performance of solar PV installations. This can in turn enable them to construct models that can help them forecast electrical power output based on varying cloud conditions and help manage fluctuations in the flow of electricity.

‘What happens when clouds pass between the sun and a large solar PV installation?’ and ‘How much is lost in the effort to convert the sun’s photons into electrons for electricity?’ were questions that remain largely unanswered until recently, NREL points out in a press release. The information in the NREL data set can be used to predict probable PV power outputs at 1-second intervals for medium- and large-scale installations.

Smoothing out fluctuations in voltage are critical to ensuring stable, grid-quality flows of electricity. Solar PV system operators can stabilize electricity flows by storing electricity or by using infrastructure and software packages, according to NREL.

“Clouds can cause pretty significant jumps or ramps over a very short period of time,” NREL senior scientist David Renne noted, adding that as solar power becomes a bigger part of the energy mix, such jumps can cause fluctuations in the grid, which can cause surges, fluctuations, and headaches for the utility operator if unmitigated.

Researchers from NREL’s Solar Radiation Research Laboratory designed the equipment so that a global positioning satellite system can be used to provide concurrent 1-second measurements for each of the 17 stations, a degree of precision necessary as solar PV systems respond quickly to shadows, Renne explained.

Funded by the DoE in support of the Hawaii Clean Energy Initiative (HCEI), the measurement system and data set enabled the NREL team “to set up a solar-monitoring network that simulates exactly how clouds would impact a large photovoltaic system,” that can be used to model solar PV systems’ output for installations as large as 30 megawatts (MW), Renne said.

“The time-synch data are unique. All 17 stations make a 1-second measurement at exactly the same time. This allows the array to ‘see’ clouds moving through and simulates how a PV system might behave. Each of the 17 measurement stations measure the solar energy in the sun’s visible spectrum that reaches a horizontal surface at ground level.”

In addition, very large arrays of solar PV panels smooth out fluctuations caused by cloud shadows to a greater degree than is the case for single panels of small rooftop arrays, the research team found.

The data was collected for the Oahu Solar Energy Study, the partners of which include HCEI, General Electric, the Hawaiian Electric Company and the Hawaiian National Energy Institute.

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