Alameda’s Power System

Alameda’s Power System

George Humphreys

Alameda has one of the oldest municipal power systems in the country. It has joined with other small and medium-sized communities to form the Northern California Power Agency. Through partnerships with various cities on specific power project agreements, Alameda can supply its power needs from clean energy sources including hydroelectric, geothermal, large-scale solar and geothermal. Power is transmitted to us from various sources over Pacific Gas & Electric Co. (PG&E) and other transmission lines. Public safety power shutoffs on portions of the PG&E system can interrupt Alameda’s power supply.

PG&E recently announced a 10-year program to bury transmission lines underground to reduce the danger of high-voltage lines sparking wildfires. This program will take over ten years to complete and cost $15 billion to $20 billion. At a cost of $1.5 million to $2 million per mile, this amounts to about 10,000 miles of transmission lines.

PG&E has more than 80,000 miles of overhead lines, so this represents about 12 percent of their system. Most of this cost probably will be passed on to rate payers. Because Alameda’s power is delivered over PG&E transmission lines our cost of delivered power probably will also increase. However, this should reduce the possibility of future power interruptions due to public safety shutoffs and wildfires sparked by PG&E system.

California has a non-profit Independent System Operator that determines what power sources are brought on-line to supply system loads. During periods of peak demand, power also can be pulled in from out-of-state regional power grids. The traditional power grid is a 20th century engineering achievement. Most of the power comes from gas-fired central station power plants, hydroelectric plants, and the Diablo Canyon nuclear plant. Little energy is stored on the system so generation functions as a just-in-time system in which generation must constantly meet demand.

Natural gas-fired turbines and hydroelectric plants can provide peaking-power demands. During drought years like 2021, low reservoir levels can force hydroelectric plants to reduce or curtail operations. Moreover, power flows one way from the generation plant through transmission lines, substations and distribution lines to the consumer.

National and state policies have been to promote the transition from fossil-fueled plants to renewable energy sources like solar and wind. Solar energy, in particular is intermittent during daylight hours and doesn’t meet the peak power demand from 5 to 9 p.m.

For the future power system, some form of energy storage such as hydro pump-storage reservoirs, large banks of batteries or in-home “power walls” will be needed. In the evolving power grid, power will flow in both directions. In fact, our homes now have “smart-meters” that can measure power flow into and out of the home.

The power system of the future seems to be moving toward “micro-grids” that could power a community for limited periods independent of the larger transmission system. A micro-grid may consist of “smart homes” in a community connected with each other and with the local distribution system, including bulk energy storage such as a large bank of storage batteries.

A solar “smart home” probably will include rooftop photovoltaic panels, an inverter, a home lithium-ion battery (storage wall), an electric-vehicle charging station, an auto transformer and smart-meter. The local “micro-grid” also would include bulk energy storage consisting of banks of lithium-ion or lead-acid batteries. In a city like Alameda, one or more “micro-grids” would be linked to the city-wide distribution system supplying commercial/industrial customers, streetlights, vehicle charging stations at parking lots and backed up by the PG&E transmission lines.

The technology for such a “smart-grid” is not yet fully developed because of the complexity of measuring real time data. Currents, phasing, voltages and other parameters at system nodes and the microprocessors and the software to control the system. In Alameda, such a system could be adopted in phases to avoid large expenditures before solar “smart homes” and electric vehicles are fully adopted.

Rutland, Vermont has established a “micro-grid” in a section of town that includes a solar farm on a closed landfill and a storage battery farm. Other micro-grids have been established around the country in Borrego Springs, California and at various universities and hospitals.

So far, Alameda does not seem to have a large fraction of homes with rooftop solar, all-electric or plug-in- hybrid cars, but this could change in the next decade.

Alameda Municipal Power (AMP) is obligated to purchase surplus power from rooftop solar during the day when the power demand is less. AMP has adopted an elective program of time-of-use rates, in which electric car owners can charge their electric cars during off-peak hours at a lower rate.

During peak hours, the rate would be higher. If a substantial number of Alameda homes install rooftop solar panels, the amount of solar-generated energy during the day time could affect the City’s ability to accept power from its contracted remote sources.

Alameda’s electric power demands could increase as air-conditioning, electric appliances replace gas appliances and electric cars are adopted. This increased demand may accommodate the available surplus from rooftop solar. What are the vulnerabilities of the new smart-grid and the transition from fossil fuels to wind and solar?

1. Smoke from wildfires may interrupt the availability of solar energy for protracted periods. For instance, last year we had a period of a week with dim light and lower temperatures due to smoke from wildfires.

2. In the last couple of hundred years, we have had large explosive volcanic eruptions that blanketed the planet’s skies and cooled temperatures worldwide. Examples are the eruptions of Krakatoa and Mt. Tambora in Indonesia, and Mt. Pinatubo in the Philippines.

3. The complexity of the control systems for the smart-grid and micro-grids may make the system more vulnerable to cyber-hackers and ransomware. The solution might be a completely separate network (5) independent of the world-wide web.

4. Owners of rooftop solar power feel they are entitled to the full cost of power (both generation and transmission). If a substantial fraction of our power comes from rooftop solar, who pays for the transmission system and generation needed to back up the local micro-grids?

5. In any new technology like solar panels and lithium-ion batteries, there is some limit as to how fast they can be adopted on a large scale due to production capacity. There also may be limits on raw material sources and ores.

6. A limited number of manufacturing sources such as China and Korea for photovoltaic cells and Tesla for lithium-ion batteries may allow suppliers to increase prices as demand grows.

George Humphreys lives in Alameda.