We look here at the CO2 cleanliness or pollution of power imported into California. This is reported as two groupings as Southwest or Northwest. The numbers work out nicely as fractions. The 2014 California power output is 296,843 GWh (GigaWatt hours), which we will call 300 (TeraWatt hours, TWh). The in-state generation is 198,973 GWh, which we will call 200 TWh. So 100 TWh, or one-third, is imported power. Of this, 60,609 GWh (20.4% of the total) is Southwest power (61 TWh), and 37,261 GWh (12.6% of the total) is Northwest power (37 TWh).
The 37 TWh of NW imports are mostly Wind (10,151 GWh), or 31% renewables, and Unspecified (25,676 GWh or 26 TWh), or 69%. The unspecified is hydro and newer natural gas plants.
The 61 TWh of SW imports are 29% coal, 17% natural gas, 14% nuclear, 6% renewables (solar, wind, geothermal), 3.5% large hydro, and 31% unspecified. The unspecified is highly efficient combined cycle natural gas plants and some coal.
NW unspecified is hydro plus newer gas plants. It would be helpful to know if these newer plants are the more efficient combined cycle plants. SW unspecified is the more efficient combined cycle natural gas plants and some coal.
The unspecified power for California is the sum of the NW and SW unspecified powers, making up 15% of the California power mix.
We apply the scale of CO2 pollution where natural gas is 1, coal is 1.78, and clean power is 0. I have used this in the previous two articles in this blog.
For the NW, the known sources are clean, giving 0, but adding 0.69 for unspecified.
For the SW, the weighted pollution index is 0.29 x 1.78 + 0.17 x 1 + 0 = 0.52 + 0.17 = 0.69 and adding 0.31 for unspecified.
The utilities total power produced is the relevant factor in CO2 pollution, along with their power mix. The power produced by the five largest California utilities in 2014 are shown below. Also included is their percentage of the total California power production of 296,843 GWh.
SC Edison 82,849 GWh 27.9%
PG&E 82,840 GWh 27.9%
LADWP 27,628 GWh 9.31%
SDG&E 17,670 GWh 5.95%
SMUD 10,319 GWh 3.48%
Their sum is: 221,306 GWh, which is 74.6%. The remainder of utilities must generate 24.4%. So the top two producers generate 56%, and the top five generate 75%.
The sum must include their out-of-state imports, since the total in-state power for 2014 was 198,973 GWh, which is less than the sum above. The in-state total actually includes the out of state power generated by the power plants owned by the California utilities. The installed capacity of the 1,051 in-state plants totals 86.883 GW (GigaWatts).
So do the sum of unspecified sources in the various utilities equal just the sum of the NW and SW unspecified, or cover more?
In trying to understand the Unspecified power, I added that from the five leading power utilities, multiplying their Power Content Label Unspecified percentage by their overall power output. That gave for Unspecified power:
PG&E at 21% = 17 TWh
SCE at 40% = 33 TWh
LADWP at 7% = 2 TWh
SDG&E at 20% = 4 TWh
SMUD at 8% = 1 TWh
Total = 57 TWh.
However, the sum of California Unspecified Power is the sum of
NW 25.7 TWh + SW 18.8 TWh = 44.5 TWh.
Since the sum of the five largest utilities at 57 TWh is only a part of the sum of all untilities, this is quite a discrepancy from my understanding of the California Power Content label explanations.
My guess, is that the State Power Label has the total of all power contracted for in the state, but some state power is sold on the spot market, and this is included with individual utilities under Unspecified Power. Since power produced in the State of California has almost no coal power, the state produced unspecified power is probably a mix of natural gas and renewables, and therefore is fairly clean. I am seeking clarification on this discrepancy.
