Distributed Energy Resources (DER) is defined as smaller-scale power generation or storage. It is also known as Distributed Resources or Distributed Generation.
Equipment associated with DER can be connected directly to the customer’s building or interconnected into CPS Energy's distribution system. DER system sizes typically range from five kilowatts (5 kW), which is the approximate demand for a typical residential customer to up to 10 megawatts (10 MW) for large commercial or medium industrial installations.
Major types of DER are:
Combined heat and power (CHP, or cogeneration)
Photovoltaic (PV) cells collect the sun’s energy and convert it directly into electricity, using solar cells comprised of semiconductor material. PV systems have numerous advantages:
No moving parts
Requires little maintenance or regular scheduled maintenance
Can be stored in deep-cycle batteries for evening or back-up use
A PV system produces DC power compared to the 120V AC power supplied by utility companies. This requires special equipment to convert DC to AC power called an inverter.
Landfill gas is produced by decomposing garbage which is collected and either flared off or used to produce electricity. Landfill gas is a mixture of gases including carbon dioxide (CO2) with the largest component being methane gas. This gas can be captured and used to power a turbine generator thus producing electricity.
Combined Heat and Power (Cogeneration)
Combined Heat and Power (CHP) devices produce both electrical and thermal energy and use the heat or steam for industrial processes, heating or cooling. It is one of the most common forms of increasing energy efficiencies.
Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity. Due to the lack of wind production in this region of the state, wind power is not recommended for significant energy savings as opposed to other regions of the state.
Micro Turbines are small combustion turbines that can produce between 25 kW and up to 500 kW of power and consist of a small gas turbine that drives a generator. They may be used to burn a variety of fuels including natural gas, fuel oil and landfill gas in order to produce electricity.
Energy storage can be achieved by devices or physical media that store a form of energy to be used at a later time. The most common at this time are fuel cells and battery storage.
The Future of Distributed Energy Resources
As DER progresses it may become a tool in addressing environmental challenges in our world. Renewable energy sources like solar and wind (from the west and southern coast of Texas) are part of CPS Energy’s overall strategy to meet Greater San Antonio’s energy needs with diversified sources.