Demand Energy Wins Sitri Funding for Energy Storage

An energy storage company, Demand Energy, will receive $350,000 in new funding ($100,000 loan/$250,000 grant), winning one of five awards from The Sirti Foundation . The project involves integrating the company’s storage system (30kW) and network management software with renewable energy resources, such as solar/photovoltaics and wind, and installing them in a large commercial facility.

Five projects from among twenty applicants were awarded a total of $1.5 million from the Sirti Foundation Energy Innovation Fund. The Fund was made possible by an award from the Washington State Department of Commerce State Energy Program under the American Recovery and Reinvestment Act.

Demand Energy's product called the “Demand Shifter” is a distributed, flexible energy storage device, to and from which utility resource managers can dispatch load based on availability and need. The storage technology is chemical battery media, typically an advanced form of lead-acid battery technology. The re-generation subsystem powers a rotating motor assembly that transforms into an induction generator. The generator mechanism is a specialized DC motor with auxiliaries.


Caption: The Demand Shifter extracts energy from the grid, stores electricity in its batteries, and reintroduces energy back into the grid when it is needed most.

Demand-Shifters are presently designed for high density and custom site deployment.

High Density deployments range through three basic output capabilities; 5kw, 30kw and 110kw (it is also possible to sequence devices together for additional flexibility and special requirements). Typical high density deployment scenarios vary from neighborhood residential, high concentration/population load centers, to small to medium industrial, commercial and agricultural applications.

Custom site deployment units are supplied for sizes over 500kW (up to 500kW, the cost-per-kilowatt and kWh favors multiple linked high density unit installations). Base unit sizes will have 2-hour runtime battery storage capacity. Additional capacity is available in hourly increments.

The electric utility interconnection requirements vary with the Demand Shifter unit size and state-by-state regulation, however all Demand Shifters have points in common that simplify interconnection. Those points are:

• All units are supplied with integral non-directional over-current detection circuit breaker subsystems that meet service entrance requirements.
  
  
• All units connect to the utility system using industry accepted motor-starter technology.
  
  
• The induction generator self synchronizes with the grid utilizing both voltage and frequency from the grid. An “energized-line” is required by the electro-mechanical design for generation to occur.
  
  
• Loss of the utility energy source results in mechanical shut down by design. No “islanding” detection subsystem is needed.
  
  
• When generating, all units provide positive power system stability response to system disturbances. Optional unit control system parameters allow for automatic unit startup in response to frequency deviations.
  
  
• Transient response to external system fault conditions mirrors similar sized induction motor response. This allows for standard utility distribution fusing and fault-study responses while deploying distributed generation devices.
  
  
• Units use induction-generation and are incapable of powering a local grid.
  
  
• Units do not function as “UPS” for local loads.
  

The 5kw single phase requires a 50 amp interconnection and disconnect. This may require a local disconnect similar to a hot tub, heat pump, swimming pool, or air conditioner. However an electric plug similar to an oven or a stove is expected to be adequate in most locations. An appropriate circuit breaker feeding this circuit should be supplied according to local codes and standards.

The 5kW 3-phase unit's interconnection requires a 4 wire grounded receptacle. For 240Vac this needs to be a 30 amp rated receptacle and for 480Vac a 15 amp rated receptacle. The 5kw 3-phase units will be supplied with 10 feet of connecting cable and appropriate plug. An example 3-phase plug is shown to the left. This is only an example since local codes and standards will establish the design. An appropriate circuit breaker feeding this circuit should be supplied according to local codes and standards.

The 30kw size units are 3 phase 480Vac only and require a 4-wire grounded connection. The connection requires a 60 amp receptacle. The 30kw 3-phase units will be supplied with 10 feet of connecting cable and appropriate plug. An example 3-phase plug is shown to the right. This is only an example since local codes and standards will establish the design. An appropriate circuit breaker feeding this circuit should be supplied according to local codes and standards.

The 110kw size units are 3 phase 480Vac only and require a 4-wire grounded connection. The connection requires a 225 amp direct wire connection to a panel mounted circuit breaker. The 100kw 3-phase units will not be supplied with connecting cable.

These units must be hard-wired into an appropriate electrical panel and terminated on 225 amp circuit breakers in accordance with local codes. An example 3-phase 225 circuit breaker is shown to the left. This is only an example since local codes and standards will establish the design. Conduit and other needed accessories are not included with the quoted packages and must be included in the site specific design.

Demand Shift units sized 500kW and over will be site-specific designed to meet utility interconnection and placement requirements. For example the electric utility may desire a 1000kW unit be located within the confines of an existing substation fenced area. Typical interconnection voltages for a site such as this range from 2400V to 34.5kV.