Total Cost to Replace Diablo Canyon with Solar Power Plants Tops Out at $83.8 Billion!

Anthony J. Armini, PhD.

Several CGNP scientists have recently completed a study to determine the costs and logistics required to replace the electric generating capacity of Diablo Canyon Power Plant (DCPP) with a number of Topaz class 500 MW Solar Plants. To replace DCPP’s 18,000 GWh per year of steady electricity requires a 3 component approach.
  1. A large number of Topaz class Solar PV farms to deliver a steady flow of 18,000 GWh per year of electricity.
  2. Pumped hydro-storage facilities to maintain power at night and cloudy days.
  3. Additional transmission lines to deliver power to the storage facilities and the rate payers.
To functionally replace DCPP on California's power grid requires that the power be dispatchable 24-7. Solar PV (e.g. Topaz) power is dispatchable for only about 5 hours per day. The peak output is about six hours early relative to California's peak power demand. Thus, a massive energy hydro-storage system must also be constructed. Here's a preliminary design to equal DCPP.... The equivalent of seven more Helms Pumped Storage Facilities (HPS) would be required. The cost for the added storage is projected to be $35 billion. While the design of HPS is fairly efficient, it is only 75% efficient. Thus, the input solar PV energy must be increased by 133% to 24,000 GWh per year to compensate for storage losses. Per the US Energy Information Agency (EIA), in 2015 Topaz Solar produced 1,301 GWh. Therefore, 18 new Topaz Solar Plants would need to be constructed for a cost of $43.2 billion. Thus the total construction cost is to replace DCPPs steady energy source (items 1 and 2 above) is $35 billion + $43.2 billion or $78.2 billion. In addition, this project would require 171 square miles of land and building these solar farms at the rate of 2 per year, would probably take at least 9 years to complete.

However to complete this new power network, additional transmission lines need to be built to connect the 18 new solar power plants to the remote storage facilities (hydro-storage must be located in the mountains) and to the power customers.

Staff of the California Energy Commission (CEC) have completed an assessment of the state's transmission grid and its ability to bring online large amounts of additional renewable capacity. The CEC estimates that upgrades and additional High Voltage lines will cost about $5.6 billion. The report can be found here.

So the complete system to replace DCPP would cost $78.2 billion for items 1 and 2 plus $5.6 billion for item 3 comes to $83.8 billion. The total construction cost in 1985 to build DCPP was only about $5.5 billion and the plant could certainly continue to operate until 2050. The plan to make a new investment of $83.8 billion to replace DCPP, an existing facility needing no new investment and can deliver emission-free electricity until 2050, is the height of foolishness which only government could propose.