Guest post by Dr Gene Preston. Gene has had a long career as a power system engineer, performing generation planning, transmission planning, and distribution planning for Austin Energy. He is currently doing transmission studies for wind developers. He wrote all his own modeling software including the current network model used to perform his consulting studies. His PhD dissertation was in power system reliability, a composite generation and transmission probabilistic model, and is posted on his web page.
Today utilities are faced with a seemingly impossible problem. Renewables are more costly than non-renewables. How is a utility to invest in wind, solar, and new nuclear without causing unacceptably high rates? Before I suggest a solution, we need to consider the role wind, solar, and nuclear will play in the power system of tomorrow.
Wind power will eventually be able to provide about 20% of our national energy. Its growth rate is only constrained by the transmission system and saturation within a region. By saturation, I mean that the hour-by-hour dispatch of a region can only accommodate a certain amount of wind, which is consistent with 20% of the energy being wind. If we try to push wind beyond that amount, we cause wear and tear on other generators and burn fossil fuel inefficiently. We could build a rather extensive transmission super highway interconnecting the different regions of the US in order to accommodate more than 20% wind. However, the impacted public usually opposes new power lines. Building a national transmission plan to accommodate large amounts of wind power will take decades and is neither politically nor economically advisable.
That leaves solar and nuclear to fill in the other 80% of the future energy requirement. Consider that the daily load pattern of a utility looks roughly like a sine wave on top of a constant load with the peak of the day occurring during sunlight hours. This suggests that the preferred amount of solar power would roughly match the sine wave component of the daily load pattern, while nuclear would provide the remaining base load energy requirement.
The new power system is best described from an individual homeowner’s perspective. Getting off the grid is not advisable because the homeowner’s batteries would be expensive and short lived. Rooftop solar will be nearly twice as costly as centralized tracking solar, and many customers are not able to install rooftop solar. The grid will be necessary for delivering power from large efficient centralized solar and nuclear projects.
How do we finance these high capital cost projects?
Since utilities do not want to generate rate increases with these investments, it is up to us customers to help finance these necessary (i.e. save the planet) future projects. The utility would offer a rate of fixed payments to cover the plant cost and then deduct the amount of energy due to the customer’s “investment(s)” from the customer’s monthly bill. For example, I could invest $8000 for 2 kW for my portion of a large scale solar plant and $8000 for 1.5 kW for my portion of a larger nuclear plant. This would provide an annual 16,000 kWh of nearly free energy for 30 years (3500 kWh/yr solar + 12500 kWh/yr nuclear). The utility would take on the tasks of metering, billing, and operating these large centralized plants. We customers provide the fixed payments to finance our kW amounts purchased. The utility would not need to raise any new capital to finance the solar and nuclear plants.
From the utility’s perspective, a centralized solar 300 MW plant at $4 per watt will cost 1.2 billion dollars and require about 80,000 homeowners to pay for half the cost. The other half would probably be paid for up front by businesses. If the $8000 cost seems high for 2 kW, keep in mind the energy cost is nearly free for the next 30 years.
A new 300 MW light water reactor nuclear plant at $6 per watt should cost about 1.8 billion dollars and require about 80,000 homeowners to pay for a little less than half the cost with the rest paid for up front by commercial and industrial customers seeking a stable base load power source (electronics and solar manufacturing companies need constant reliable power sources). If the $8000 cost seems high for 1.5 kW, keep in mind the nuclear energy cost is less than 2 cents per kWh and could continue for 60 years. Because the new solar and new nuclear plants can be located near load centers, new transmission can be minimized, unlike the transmission requirements for new wind power, which can be extensive for large amounts of wind in an area with few power lines.
What about the nuclear waste and nuclear security problems? The current light water reactor design requires that naturally occurring U235 be enriched from 0.7% to about 5%, depending on the specific design of the nuclear plant. During the operation of the LWR plant the percentage of the U235 decreases after a few years and the used fuel is removed and stored on the plant site. Note that the waste has nearly the same amount of uranium it had when it was shipped to the plant for initial loading. The problem with the waste is that it also contains other radioactive products that have long half-lives.
However, after a few decades this material is not as dangerous as most people think. The nuclear waste can be handled safely wearing gloves. It’s just too toxic to ingest. We need to insure it doesn’t get into our water and air. Since the total amount of nuclear waste is about a million times smaller in volume that the toxic waste from coal plants, the storage of nuclear waste is not a very large environmental problem at this time. However, we do need a long-range plan for using or disposing of this material.
Fortunately there are many plans on the drawing boards around the world for turning nuclear waste back into nuclear fuel so that uranium mining may not be needed for hundreds of years. The US developed IFR process that was partially tested in the 1990s should be able to burn up all the U235 and U238 and highly radioactive heavy metals so that after a couple of hundred years, little radioactive waste will remain. The University of Texas has a plan for a fission-fusion reactor that will also burn up nuclear waste. This is a small physical plant that could prove to be low cost and efficiently dispose of the nuclear waste. And then there is India, which is planning to power up a fleet of thorium reactors. These reactors could use the US supply of highly radioactive heavy metals as their starter material. The IFR and thorium reactor byproducts are not suitable for bomb making without extensive further processing. So what we consider as toxic waste now has future economic value if we can patiently wait for those uses to be developed.
So what about security? Modern nuclear plant designs incorporate multiple fail-safe levels so that even the stupidest nuclear plant operator could not cause a meltdown (China Syndrome). The reactor materials are not suitable for bomb making. The danger of nuclear proliferation will require a worldwide monitoring and enforcement program.
Postscript: How does this relate to Australia? Gene said the following to me:
Barry, if you cannot get the Australian government or utilities interested in investing in nuclear power in Australia, I suggest that you try to get a rate structure set up that allows solar, and wind, and nuclear power sources to “invest” in their favorite energy sources through a special rate structure. That rate needs to separate the capital costs from the fuel costs. Then, depending on the amount of kW the customer has committed to, there are fixed costs in the bill paying for the capital costs, and there are fuel and O&M costs in the bill. Once you have customers signing up for the nuclear rates, then you have a basis for building a plant that matches the customer’s nuclear interests. Give each individual person in Australia an opportunity to buy the power source of their choice. Wouldn’t you like to have this ability yourself?
My objective is to try to give individuals an opportunity to buy whatever kind of power they choose by providing an obligation to make payments toward the capacity of that kind of generation source. I hope we can get our solar friends as allies to get this implemented. In this way we are not in conflict with them but join them as partners. Of course we will choose nuclear and they will choose solar, but that is ok…