Energy Supply and Generation Methods

DER Graphic – Credit: Jayanth Rangaraju, Texas Instruments

In the early stages of a CCA’s operation, the agency procures solar, other renewables, and conventional electricity from the wholesale electricity market. But over time, it makes sense for a CCA to start tapping and deploying renewable energy, mostly solar, closer to home. Indeed, the established CCAs in California have demonstrated that developing local and regional energy resources can not only increase the amount of affordable renewable energy available but also have the potential to generate jobs, stimulate local economic development and increase community resiliency.

Much focus is on solar as it is the most deployable, least objectionable technology, but CCAs already are exploring and, in a few cases implementing other local energy generation options such as wind power (including off-shore wind), biomass, hydroelectric, and geothermal. As CCAs become more established and as technologies mature, we can expect much more of this innovation.

In each sub-section below, you’ll find information in the following general categories.

  • Overview
  • Relevance for CCAs
  • Opportunities for Action
  • Resources and Partners

In addition, please visit our DER Projects Clearinghouse where you can learn about specific projects or programs that CCAs are implementing with each of these methods. Search and filter by CCA, technology, goals, location, etc., see summary project information, and most importantly, who to contact for more information to accelerate your own efforts.


Duck Curve: Credit: CAISO

Solar is a wonderful power source, but CCAs and other LSEs have found that solar can no longer be added to the California grid without also adding coincident load or storage. The infamous “duck curve” to the right depicts the impact of substantial penetration of solar on the daily load shape on some days in California. The two points of concern are the belly of the duck, where “surplus” solar energy is in need of use, and the other is the steep ramp in the evening when solar declines and people plug in. Therefore, it is important that solar advocates and stakeholders remain engaged in the CCA planning process to ensure that the policies and programs the agency adopts are favorable to deploying solar in tandem with technologies that can use or store the electricity. Flatten the duck!

There are several different types of solar technologies that harvest energy from the sun. With regard to DERs, we are talking mostly about solar photovoltaics (PV), the solar panels that convert photons directly into electricity.

The other solar technology that has relevance to DERs is solar thermal, or solar water heating technologies. Solar Thermal has a long, well-established track record of excellent performance and can be considered in some commercial and industrial DER applications where hot water is required. This type of technology is always meant to serve an on-site need, as transporting hot water over long distances is not efficient.

Other solar energy harvesting technologies are utility scale and tend to be either very large solar PV arrays or facilities that use mirrors to concentrate solar to a focal point to create steam or molten salts, generally known as concentrating solar power systems. These system have little relevance to DER deployments.

Relevance for CCAs

One of the most powerful aspects of Community Choice Energy is that it redirects an existing stream of tens or hundreds of millions of dollars into local control. There are several ways that some of these funds can be harnessed to increase the deployment of solar energy in a community or service area, thereby fostering local economic benefits.

  • Reduced customer energy costs mean that motivated customers can more easily invest in rooftop solar for their homes and businesses.
  • Net revenues accrued by the CCA can be reinvested in the community in the form of customer incentives such as increased generation credits and community education programs supporting residential solar.
  • Community-scale solar projects can be designed and built. In addition to generating more local renewable energy, after costs are recouped, these projects can generate on-going revenues.

Opportunities for Action

Please use the DER Projects Clearinghouse to search for and learn about related projects and programs implemented by California’s CCAs
  • Net Energy Metering (NEM) — enables customers who generate some or all of their own electricity (e.g. with rooftop solar panels) to reduce their energy costs through credits on their bills. In some cases, they may be compensated for surplus electricity they feed into the grid.
    • See for example Peninsula Clean Energy’s “Solar Customers”:
  • Feed-In Tariff (FIT) — enables individuals and businesses to install renewable energy systems (e.g. usually up to about one megawatt of solar or wind power) and by means of long-term contracts to be compensated for the renewable energy they provide to the grid.
    • See Sonoma Clean Power’s “ProFIT” program:
  • Community Solar — Larger solar facilities (typically more than one megawatt) that generate electricity either provided directly to the grid or to subscribers in a community.
    • See Marin Clean Energy’s “LocalSol” program:

Resources and Partners

California Solar & Storage Association (CALSSA)

CA Energy Commission’s Solar Energy Statistics & Data page

Solar Energy Innovation Network, National Renewable Energy Lab

Solar Plus, A Holistic Approach to Distributed Solar PV, National Renewable Energy Lab

Solar-Plus-Storage 101, U.S. Dept. of Energy

California Community Choice Association (Cal-CCA)

Shiloh Wind Farm and Cow – Solano County, California Photo Credit: Woody Hastings


Wind power has arrived in terms of being a competitive, reliable utility scale form of electricity generation. In fact, it is now among the cheapest forms of energy generation and along with solar, accounts for most new generation constructed each year.

Relevance for CCAs

Utility Scale: Wind is certainly distributed, but it is not distributed evenly. For most CCAs, utility scale wind power is not a local resource. People have tended to settle in places where the wind does not blow too strongly on a regular basis. Therefore, our cities and towns – the electricity load centers – tend to be distant from good wind resources. However, wind can play an important role in balancing a CCA’s load profile and providing opportunities for storing remotely generated power within CCA service territories for local use.

Small Scale: There are several small scale wind turbine manufacturers that offer “backyard” wind turbines that may be applicable in some DER deployments. Although conditions need to be right for a small turbine to be effective, small scale wind systems do exist and are continually being improved upon. See resources below.

Opportunities for Action

Several opportunities present themselves for CCAs with regard to wind and DERs.

Wind tends to generate most of its power during the night. CCAs can procure wind power as a means of complementing the daytime presence of solar power thereby flattening the load shape and allowing yet more solar to be added as required. So even though wind power procured on the wholesale market would not be considered a DER, it can help facilitate the efficacy of a DER deployment.

Onshore, in-state: CCAs can take a lead in procuring wind within the state of California, benefiting the California economy and creating jobs in the state.

Offshore: Thirteen coastal California counties either host operational CCAs or are in a process of forming a CCA. Each one of these CCAs can explore the opportunity of harvesting the steady utility scale wind that exists not far from the shoreline, but just far enough out that it does not impair the ocean view. One such CCA, Redwood Coast Energy Authority, is in the process of developing just such a project.

Resources and Partners

Distributed Wind Energy Association, a collaborative group comprised of manufacturers, distributors, project developers, dealers, installers, and advocates, whose primary mission is to promote and foster all aspects of the American distributed wind energy industry. Distributed wind, commonly referred to as small and community wind, is the use of typically smaller wind turbines at homes, farms, businesses, and public facilities to off-set all or a portion of on-site energy consumption.

Small Wind Guidebook and Small Wind Electric Systems, U.S. Dept. of Energy

Wind Works, a wind energy resource page managed by Paul Gipe

Redwood Coast Energy Authority Offshore Wind Project

California Wind Power Statistics & Data, CA Energy Commission

American Wind Energy Association

Geysers Plant, Mayacamas Mts., Sonoma County. Photo Credit: Woody Hastings


There are several different kinds of geothermal technology.

  • High temperature geo-electric steam plants
  • Low temperature District Energy systems
  • Ground source heat pumps

Relevance for CCAs

High temperature geo-electric steam

This resource is not considered a DER by most folks and offers limited opportunity for CCAs. It is limited geographically to places where hot magma is relatively close to the Earth’s surface. The largest single geothermal field in the world, the Geysers, happens to be located in the Mayacamas Mountains in Sonoma County. It is not cheap power but it is very low in greenhouse gas emissions and qualifies under the State’s renewable portfolio standard as eligible renewable energy. The chief value as a component in a CCA’s power mix is that it is baseload power, meaning that other than occasional planned down time for maintenance, it is available 24/7/365 and helps provide a load platform on which to add variable resources. Regardless of geographic location geothermal power, like all utility scale power, can be procured by any CCA and can be wheeled anywhere in the State.

District Energy

District energy is a proven technology that has been around for decades. District heating is an underground system where thermal energy is provided to multiple buildings from a central energy plant. Steam or hot water is transmitted 24/7 through highly insulated underground thermal piping networks. The thermal energy is transferred to the building’s heating system, avoiding the need for boilers in individual buildings.

Ground source heat pumps

A geothermal heat pump or ground source heat pump is a heating and/or cooling system that uses the constant temperature of the earth as the exchange medium instead of the outside air temperature as in the case of an air-source heat pump. Fluids of varying types are used to transfer heat to or from the ground. They are available 24/7 without any intermittency as a heat source or a heat sink. During the winter the fluid collects heat from the Earth and carries it through the system and into the building. During the summer the system reverses itself to cool the building by pulling heat from the building, carrying it through the system to the ground. This process creates free hot water in the summer and delivers substantial water-heating cost savings in the winter.

Opportunities for Action

Several opportunities present themselves for CCAs with regard to District Energy and ground source heat pump geothermal applications.

In the case of district energy, CCAs can assess commercial, industrial, and institutional campuses in their service territories and identify good prospects for district heating and/or cooling. District energy can serve as a component of an integrated DER deployment.

Likewise, ground source heat pumps can be a component of an integrated DER deployment in residential and non-residential settings.

Resources and Partners

International District Energy Association

International Ground Source Heat Pump Association

The Geysers

Geothermal Energy Statistics & Data webpage, CA Energy Commission

Geothermal Heat Pumps, U.S. Dept. of Energy

Most Efficient 2019 — Geothermal Heat Pumps, Energy Star

Biomass Types
Credit: U.S. Energy Information Administration


Bioenergy facilities can have impacts on local communities so siting, truck traffic, odors, dust, and other considerations should be taken into account in considering off-taking from or helping to develop bioenergy facilities.

There are four main kinds of biomass electricity generation:

Incineration to produce heat or generate electricity

Wood and wood processing wastes are burned to heat buildings, to produce process heat in industry, and to generate electricity

Conversion to liquid biofuel

Agricultural crops and/or crop waste materials are converted to liquid biofuels

Conversion to biogas

Animal manure and/or sewage is converted via anaerobic digestion to biogas (methane), which can be burned as a fuel

Landfill gas-to-energy

Methane produced by organic matter decomposing in landfill is captured and converted – burned – to generate electricity

Relevance for CCAs

Several operational CCAs are already harnessing bioenergy sources for electricity generation. MCE has its 3.9MW Redwood Landfill gas-to-energy plant near Novato, CA, and the Redwood Coast Energy Authority has contracts with Humboldt Sawmill Company in Scotia and DG Fairhaven Power on the Samoa peninsula, which together account for about a quarter of RCEA’s power mix.

In limited settings, such as agricultural operations, appropriately sited bioenergy facilities may serve as a component to an integrated DER deployment where the bioenergy is either used directly to replace fossil gas use, or as a means of generating electricity onsite

Opportunities for Action

Bioenergy facilities typically include multiple stakeholders, high O&M costs, feedstock logistics, local impacts, and other factors that make siting and operating bioenergy facilities complex. Any single jurisdiction CCA or member jurisdiction of a joint powers CCA that has a landfill within its jurisdiction that is currently flaring landfill gas should seriously consider harnessing that gas as an electricity generation source.

Resources and Partners

Bioenergy Association of California

California Biomass Energy Alliance

Redwood Coast Energy Authority Local Biomass Power

MCE Redwood Landfill Gas-to-Energy Plant

California Biomass and Waste-to-Energy Statistics & Data page, CA Energy Commission

Landfill Gas Power Plants, CA Energy Commission


25 MW Friant Dam on the Central Valley’s San Joaquin River
Credit: Friant Water Authority

There are three broad categories of hydroelectric generation: large-scale (30 MW+), small-scale (<30 MW), and microhydro (less than 100 kilowatts in capacity). Large Scale: Large-scale hydro-electric power is neither a distributed resource, nor is it an eligible source under the State’s Renewable Portfolio Standard to count as renewable energy. This policy is due to non-energy-related ecological impacts of large dams. Small Scale: Small-scale (30 MW and less) hydro-electric generation does count in the RPS, and may be more available in several CCA service territories where rivers incapable of sustaining large scale hydro-power are able to provide for a smaller scale plant. Microhydro: Usually less than 100 kW, microhydro systems are limited, as with all hydropower, to locations where water flow is adequate to drive turbines or screws to generate power. Given that they require much less water, there are more opportunities for deploying microhydro systems. Such systems can offer a good complement to on-site solar given that they produce power during the night as well as the day. Last but not least, a well-established energy storage method known as pumped hydro storage may also play a role in a CCA DER deployment. Since pumped storage is not generation per se, see more about pumped storage in the Demand Side / Non-generation section of the DER Hub in the storage category.

Relevance for CCAs

Small-scale hydro-electricity: CCAs may step up as an off-taker for existing small scale hydro and may participate in developing appropriately-sited and managed new facilities.

Pumped storage: CCAs may contract for power stored at existing pumped storage facilities and may participate in developing appropriately-sited and managed new pumped storage facilities.

Opportunities for Action

CCAs can explore local opportunities for benefitting from existing facilities or all types, and can assess opportunities for appropriately sited and managed new facilities except large hydro.

CCAs can evaluate the costs and benefits of offering incentives for property owners to develop appropriately sited and managed microhydro systems.

Resources and Partners

California Energy Commission’s Hydroelectric Statistics & Data website

National Hydropower Association Small Hydro page

US Dept. of Energy Microhydropower page