Friday, February 13, 2009

AB 32 and the Electric Power Sector

Under California's AB 32, aka Global Warming Solutions Act of 2006, greenhouse gases must be reduced to 1990 levels by 2020.  The greenhouse gases, GHGs, are primarily emitted by the Transportation sector (38 percent of the total), followed by Industrial (20 percent), then by the Power Generation sector (23 percent), and by Commercial and Residential (9 percent). 

The Power Generation sector is complex, and has several aspects.  Firstly, some power is generated for sale in the state, some is imported from other states, and some is generated and consumed on-site.   Secondly, power imported and generated for sale must be balanced by the customers' demand (Commercial and Residential sector), as there is no practical way to store power (leaving aside for the moment pumped storage hydroelectric). Thirdly, California has imposed strict new laws affecting both imported power and generated power for sale.  Imported power cannot be generated by coal, or natural gas, unless the heat-rate is at least as efficient as a natural-gas-fired combined cycle cogeneration plant.  Fourthly, no new nuclear power plants may be built in California, by state law.  Finally, power generated from renewable sources must comprise 33 percent of the total state-wide power by 2020.  This last is the Renewable Portfolio Standard, RPS.   There is an medium-term requirement for RPS of 20 percent by 12/31/2010.  

Given all this, AB 32's Scoping Plan states that electric power contributions to the GHG reductions shall constitute improvements (reductions) from building and appliances, additions to combined heat/power generation, renewable generation, and One Million Solar Roofs.  The reductions are expressed as Million Tonnes of CO2-equivalent per year, and are as follows:

Buildings/appliances...........................19.6 MMTCO2e
CHP - 30,000 GWh combined heat and power generation at 4000 MW .....6.7
Renewable Portfolio Standard..........21.3
Million Solar Roofs..............................  2.1
Electric Energy Efficiency..................15.2

The High Speed Rail is also to reduce CO2 by 1 MMTCO2e per year, but it will undoubtedly consume electric power to do so.  How much is not stated.   I will leave that to the side.
There is another large amount of CO2 reductions that is not specified as to source or origin, in the amount of 34.4 MMTCO2e, listed as Additional Reductions Necessary to Achieve the Cap.  I believe this means, 'We are not really certain what happens here, but we need this amount to achieve the goal.  Stay tuned, we will make this part up later.  Trust us.'

The task is to unravel all this into discrete actions, and determine who has to do what, and to what extent.  Then, we can determine the costs and benefits, and feasibility of achieving the goals by 2020.  

Electric Energy Efficiency

Electricity efficiency is one discrete action, and it is shown as 15.2 MMTCO2e per year. This measure is implemented by upgrading old appliances and motors to new, high-efficiency appliances and motors.  Appliances include refrigerators, freezers, air conditioners, heater system fans, electric stoves and ovens, dishwashers, clothes washers, and electric clothes dryers.   15.2 MMTCO2 per year equates to roughly 5500 MW of power run full time, 24 hours per day every day.   The problem lies in that none of the appliances runs 24 hours per day, every day.  The intent of AB 32 is to replace old, inefficient appliances with modern, high-efficient appliances such that some MW of electric power is reduced from the power grid.  It is far more likely that the hours per day that the appliances operate is something like 3 or 4 hours per day, but I will use 6 hours per day to illustrate this point.  Using 6 hours each day requires the 5500 MW to be multiplied by 4, and we get 22,000 MW power not needed.  

Knowing that there are approximately 15 million homes and apartments in California, based on a population of 37 million and roughly 2.5 people per dwelling, we can compute the power saved per dwelling and check for reasonableness.    This works out to roughly 270 kwh/month per dwelling, and at $0.12 per kwh, the savings per dwelling is almost $32 per month.   Something does not align here, as the Scoping Plan states that the savings per household will be on the order of $33 per month, and that is after allocating some of the savings to pay for the new appliances.   The net benefit is to be roughly $400 per year ($33.33/month), per household, per the Scoping Plan.   The gross benefit per month must then be approximately $68.00 per month, using $36 to pay a loan for $5000 over 20 years at 6 percent compound interest, and $32 per month to make the net $400 per year.    The $5000 for the loan is a rough estimate to replace a central air conditioning unit. 

My value from above of $32 per month is just under one-half the required value of $69 per month.   To make this work, one is required to adjust one or more of the assumptions that led to the $32 per month.  One such assumption is that the utility company will throttle back a form of power generation that has a thermal efficiency of around 40 percent, that is, one of their most inefficient power plants.   A Rankine-cycle gas-fired steam plant is  such a plant.   It would not make sense to throttle back the CCC, or combined cycle cogeneration plants, because their thermal efficiency is higher than 40 percent at around 57 percent.   One could also adjust the power price that was used in the calculations, instead of 12 cents per kwh, use 24 cents per kwh. 

It just does not make sense. 

Million Solar Roofs

Now, turning to the Million Solar Roofs, and trying to verify that those save 2.1 MMTCO2 per year.  The Scoping Plan gives the power saved as 3000 MW, running at an average of 6 hours per year per the California Energy Commission figures.  Using a power plant efficiency of 57 percent, the savings does indeed equal 2.1 MMTCO2 per year.   That 57 percent efficiency implies that ARB has in mind to throttle back the most efficient gas-fired plants, as stated above, the CCC plants.  Or, to avoid building those plants.  

Further investigation of the million solar roofs idea, from published data, reveals how much roof area is required for the average household.  Using 1 million households, we obtain roughly 330 square feet per roof, an area approximately 11 feet wide by 30 feet long.   This is based on one currently available offering for solar panels that produce 224 watts each, and are 3.5 feet wide and 5.5 feet long.  The roof array would be three panels wide, and five panels long. 

Another area where the Scoping Plan fails is for households that do not presently have an air conditioner.  Many such homes exist in coastal areas, and are cooled by the ocean breezes.  They will have little to no opportunity to purchase a new more efficient air conditioner, yet their price for power will go up along with everyone else.  Where such homes have electric kitchens, water heaters, and heating systems, there is very little they can do.  Perhaps they can install an electric heat pump for their home heating system, but the electric range, stove, and water heater will continue to consume the more expensive power.   They may be able to install a solar water heating system with the electric heater as a backup. 

Combined Heat and Power, CHP

CHP systems and the GHG savings for them under the Scoping Plan just do not make any sense.  The annual savings in GHGs is given as 6.7 MMTCO2/year.  The power generated by these systems is also stated as 30 GWh per year, with peak rating of 4000 MW.  One can then calculate that these are to run 7,500 hours per year, or roughly 20 hours per day every day of the year.   Or, it could be that these require 15 percent of every year shut down for maintenance.  It is certain that some maintenance time is required.  The CHP systems are likely to be natural-gas fired engines coupled directly to a generator, with the exhaust heat captured and converted to hot water.   These systems are useful in businesses and hotels where power and hot water are needed in fairly large amounts.  

Where the figures do not make sense is thusly:  6.7 MMTCO2/year is the amount of CO2 the CHP plants place into the atmosphere, using 7500 hours per year and a thermal efficiency of 80 percent.   What should be used by ARB is the net reduction in CO2 in the atmosphere, i.e. the amount of CO2 that would be emitted by the power utilities, less the CO2 emitted by the CHP plants.  Using the 57 percent efficiency from earlier for power plants avoided or not built, we obtain 9.5 MMTCO2/year.  Subtracting the 6.7 emitted by the CHP plants, we obtain a net savings of 2.8 MMTCO2/year.  Once again, the Scoping Plan figures do not make sense.  This is a bust.  

Renewable Portfolio Standard

The RPS has 33 percent renewable energy by 2020, and is to reduce GHGs by 21.3 MMTCO2/year.   This represents approximately 11,500 MW if running an average of 67 percent, or 16 hours per day.  This is the current average for all renewables in California, which comprises geothermal at nearly 100 percent, biomass at nearly 100 percent, and wind at approximately 25 percent.  No solar is producing significant power according to the California Energy Commission data for 2007 and 2008.    Some solar plants have been approved, and more wind plants have been approved, but the approved projects will likely fall far short of the required 33 percent by 2020.  

It is also a problem in that the new renewable power plants are likely to be wind and solar, with few new geothermal sources, plus some biomass plants.  The average generating rate is therefore likely to be much less than 67 percent, requiring more MW of installed power.  


This category is to reduce GHGs by 19.6 MMTCO2/year.  This category includes new buildings with better energy designs and with high-efficiency appliances, and retrofitting existing buildings.   This works out to approximately 14,000 MW running 12 hours per day, at the 57 percent efficiency for avoided power plants.  

If we use an average of 10 times the square footage for a building compared to a home with one of the million solar roofs, we can obtain a rough value for how many MW per building, and thus how many buildings are contemplated to be retrofitted by this.  This works out to roughly 470,000 buildings.  Or, if the buildings are smaller, perhaps only 5 times the size of a home, then there are nearly one million buildings to be modified.   The energy savings per building is approximately 30 kw.  


The Electrical Energy Efficiency does not make sense unless one uses 24 cents per kwh for avoided power cost.  Similarly, the CHP area does not make sense because it appears ARB made a flawed calculation for the net GHG reductions.   There are inequities in the Scoping Plan, as mentioned, that impact all-electric coastal homes.    Another inequity is for rental units, where only the landlord can install more efficient appliances, but the renter pays the utility bills.  The landlord must increase the rent to justify this, and that may be difficult in rent-controlled properties. 

Roger E. Sowell, Esq. 

No comments: