Natural gas plant vs. Solar plant

Reposting this beautiful, quantitative analysis from WUWT.

gas

Guest essay by Philip Dowd

Here is a simple example that illustrates why current solar technology will be hard-pressed to replace existing carbon-fired power plants.

Let’s suppose that a power company is planning to scrap a coal-fired power plant and wants to replace it with a new plant. Furthermore, let’s assume that the old plant to be scrapped is in Arizona. The options for the new plant are natural gas and solar. The company wants a simple, ball-park analysis of the front-end cost to build each of these options.

The requirements:

1. Electricity demand on this facility is 4,800 MWh/day, about the demand for a community of 160,000 average households[i]

2. The “up time” of both plants must be equal. That is, both must be equally reliable and produce the demand for the same fraction of time over the course of one year.

Assumptions:

1. The solar plant will consist of a Photovoltaic (PV) panel and a battery. The PV panel will generate enough electricity during the day to produce the necessary output and charge the battery. The battery will generate the necessary output at night.

2. Night time demand equals day time demand.

3. The new plant will be built in Arizona, a good spot for a solar plant

The Analysis

The analysis is in the form of an annotated spread sheet, showing the two options and the steps required to derive the solution.

I. Capital Cost to Generate Electricity

dowd-electricity-table-gas-solar
II.Capital Cost of Storage for Night Time Demand

The solar option requires a battery that would supply night time demand. For this purpose we will use technology known as “Pumped Storage”. This method stores energy in the form of potential energy of water, pumped from a lower elevation reservoir to a higher elevation reservoir. In our example, about half of the electric power from our solar facility produced during the day would be used to run the pumps and fill the upper reservoir. Then, at night, the stored water would be released through turbines to produce the electricity that would run the night time economy.

clip_image002

For more on this see: https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

III. Total Capital Cost Including Storage ($millions)

For our exercise let’s consider the Bath County facility, located in the northern corner of Bath County, Virginia[vii]. It was constructed in 1977-85 and is currently the largest pumped storage facility in the world.

Here are its relevant specifications:

dowd-bath-county-va-costs2

So, at this point in the exercise we have the relative costs of the two options to generate electricity over a twenty-four hour period, assuming normal operations for both. The capital cost of the solar option is about 14 times the cost of the gas option.

dowd-electricity-table-gas-solar2

Conclusion

This back-of-the-envelope analysis suggests that a solar (PV) power plant that could deliver that same results as a gas-fired power plant would cost about 14 times the gas-fired option to build. It is worth noting that the solar option cost excludes any subsidies, investment tax credits, etc, that could narrow the range, but it is obvious from this little exercise that until solar technology improves dramatically, there is little chance that it will replace natural gas as the “go-to” option for new power plants.

Bill Gates, the co-founder of Microsoft, has said that it was “fantastic” that the UN, national governments, and environmental campaigners had raised awareness of climate change and were taking steps to counter it. However, he argued that current technologies could only reduce global CO2 emissions at a “beyond astronomical” cost. “The only way you can get to the very positive scenario is by great innovation,” he said. “Innovation really does bend the curve.”[xiv]

I totally agree. Mr Gates intends to invest $2 billion in renewable energy over the next five years — innovation to bend the curve. Solar energy is going to need lots of it if it is ever to become a viable substitute for carbon-based energy.

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