Posted on 04/01/2016 8:04:15 PM PDT by Ernest_at_the_Beach
Guest Blogger / 6 hours ago April 1, 2016
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
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.
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:
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.
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.
References:
[i] Average household in US consumes about 900 kWh/month or about 30 kWh/day
http://insideenergy.org/2014/05/22/using-energy-how-much-electricity-do-you-use-each-month/
[ii] Net Capacity = electricity demand for one day ÷ 24 hrs or x/24
[iii] http://www.eia.gov/forecasts/aeo/electricity_generation.cfm
Scroll down to the table. Capacity factor is found in col 2.
The number for gas is “Conventional Combined Cycle”
The number for solar is ”Solar PV”
[iv] Gross Capacity required = net capacity ÷ capacity factor
[v] http://www.eia.gov/forecasts/aeo/assumptions/pdf/electricity.pdf#page=4
The cost used comes from col 5 in this chart: “Base Overnight Cost in 2014”
The entry for gas is “Conventional Gas/Oil Combined Cycle”
The entry for solar is “Solar PV”. Note that this cost excludes any subsidies.
[vi] Gross Capacity Required x Capital Cost
[vii] http://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station
[viii] The equation here is Capital Cost at time of construction x adjustment for inflation
For Bath = $1,600 mil x 2.6 = $4.1 trillion (inflation adjustment is for the period 1981 – 2014)
For inflation adjustment use this site: http://www.usinflationcalculator.com/
[ix] The equation here is Capacity x Time to Empty Upper Reservoir
For Bath = 3,000 MW x 14.3 hours = 43.0 GWh
[x] Assume night time demand = day time demand so night time demand on the solar battery = ½ total daily demand
[xi] Cost of Storage = Capital Cost ÷ Stored Energy = $4.1 trillion ÷ 43 GWh ≈ $100/kWh
[xii] Capex to store night time demand = $100/kWh x 0.5X kWh = $50X
[xiii] Total here is the “Total Capital Cost” in Sec I plus the “Cost of Storage” in Sec II
[xiv] http://www.ft.com/intl/cms/s/2/4f66ff5c-1a47-11e5-a130-2e7db721f996.html#axzz3kyDZjQxG
April 1, 2016 in Energy, natural gas, solar power.
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But the Democrats say that spending over ten times as much for power will create jobs.
It would be useful to know the cost of the natural gas over the lifetime of the plant, among other things.
Hydroelectric pumped storage seems very inefficient. Aren’t they working on better ways to store electricity or convert it to hydrogen?
It is not inefficient at all. Two major aspects are free. Gravity, and water. In places like California the night time demand is much smaller. Excess electricity from high load constant sources like nuclear, power the pumps that move the water back up in to the reservoirs.
Electrolysis and storage of hydrogen is hugely inefficient and very expensive. Then again... That’s just what the government wants.
Solar Panels=Crispy Critters!!!!
Well of course it’s more expensive. That’s the idea isn’t it? To give other countries a better chance at beating America?
America is handicapped now, we are too good by all standards, and we must be crippled so the rest of the world can get their slice of the pie.
This is reparations to the world for having been successful.
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.
This is a very interesting analysis.
I’m all for developing new sources of energy, but, would like to see a cost/ benefit analysis done, as you have done here.
Maybe someday solar will be competitive with other forms of energy generation. Maybe. But until such time as that happens, we should not rush to see our energy costs skyrocket, by abandoning fossil fuels, just to make a political statement.
Hillary said something along the lines of, we have to get rid of fossil fuels. But she doesn’t want to forget about the coal miners who will be out of work permanently if she can make this happen.
NatGas is cheap, and they're finding more of it all the time. It will be decades before a competing technology will under price it.
I doubt it. One of the more exotic forms of nook power will probably be ascendant.
Given that it's simpler, without a lake for night-time use or other high-tech parts--I'm sure a gas plant would have similarly low operating costs to its build costs.
Carbon-based fuel--such as oil or gas--is concentrated solar energy, and using it simply unlocks that energy. It is inevitably much more efficient, and less expensive, than any alternative energy.
Left out the environmental footprint as in how many acres each plant would occupy.
If you think this is rediculous, take a look at the Ivanpaugh Solar Plant in Southern California ( just across the state line from Las Vegas). It’s a huge looser that may have to be shut down because it’s not genrating the requisite power, and it’s a bird fryer.
The WUWT website ( Watts up With hat?) had an article on that.
There is a little truth here, though once the calculations get real, the case for solar is probably an order of magnitude lower, not to mention the risks and property costs for collecting 19,200 megawatts. There is no mention of tracking collectors nor of the efficiency of the photovoltaic cells. First, an optimistic analysis requires that the area of the solar field needs to be greater than 720 square miles. The configuration of the tracking collectors doesn’t matter, but imagine maintaining over 700 square miles of machinery in the desert, washing the surfaces of dust and sand, and where will you put the enormous storage reservoir? Large scale solar is made to order for swindlers and for the naïve. It is about energy flux density. Solar energy is very diffuse at the surface of the earth, and not much higher in space.
A rule of thumb for those who get tax incentives to put solar panels on their roofs is that in most of the U.S. where there isn’t fog half the time as in some West Coast cities, an average of 10 watts/square meter over 24 hours is a reasonable expectation. That is assuming 20% efficiency of the photodiodes, and tracking panels, which even Solar City doesn’t claim to provide. The only way that works is that government regulatory agencies can increase the cost of alternatives by killing coal, natural gas, and nuclear alternatives. That is what they’ve done, with much money in the pockets of politicians and lobbyists, from oil producing states. Islamic oil producers fund lobbyists and they get protected by the U.S. Military while taxpayers pay the resultant higher energy prices.
I’m guessing that the crude model assumes the illusory 20% collector efficiency. But pumped storage, since three quarters of the power must come from storage, is probably not better than 80% efficient. The collection surface needs to be increased.
Yes, I did these calculations when I was an idealist in college. You don’t want to depend upon utopian idealists when people’s lives are at stake.
For the solar plant it would be useful to know battery and panel replacement costs as well.
When the sun sets in the west then the solar power plant is of no use.
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