(June 2011) Dynegy appoints interim president and CEO; Navigant adds new energy practice director; plus senior staff changes at Emera, ConEdison, Energyplus Holdings, and others.
Demand Response: An Overview of Enabling Technologies
routs the signals from 200 MicroCells to the system controller located at a CellNet data center. The system controller converts the data to an appropriate format and presents it to the energy service provider over the Internet.
Communications in a Real-Time Market:
The Missing Link to Real-Time Metering?
Several technologies are available for moving data collected by meters to the utility, load aggregator, energy service provider, or customer's central location.The Power line carrier (PLC) sends communications signals over the power lines. PLC has the advantage that the communications network already exists directly to the meter. However, the following describes a few somewhat more conventional types of network communication schemes:
- Fixed Radio Networks place radio transmitter/receivers throughout the geographic area to be covered, typically mounted on utility poles or buildings. Each meter also has a radio transmitter/receiver. The network can communicate with any meter at any time. It provides the capability to support real-time energy prices, facility monitoring, daily meter reading, load profiling, time-of-use pricing, etc. Metering and sub-metering (non-billing) can give customers a better view of their facilities.
- M obile Radio Networks use technology that is similar to fixed radio networks except that the utility side transmitter/receiver is portable (either hand held or vehicle mounted) and used to make periodic contact with the meters. This reduces the cost of installing a fixed radio network but it also greatly reduces the ability of the system to support real-time operations.
- Telephone Communications are also used to communicate with meters. The meter is supplied with a telephone modem. Communications can be initiated by the meter at set times or by the energy service provider whenever necessary. If a shared phone line is used, the meter modems recognize if the line is in use and, if so, try to make the call later. If a standard telephone line is not available a cell phone (+$800) or a satellite phone (+$2000) can be used.
An advantage to telephone communications is that all of the loads in the aggregation do not need to be in the same geographic area. Another advantage is that no expensive infrastructure is required. A disadvantage is that communications take longer to initiate. It takes about half a minute to read each non-interval (monthly) meter. Reading 1 hour interval meters requires about one and a half minutes each while 15 minute interval meters require about 4 minutes each when read monthly. These times are not long if you are reading a few meters but add up if you need to contact thousands.
The inherent differences between fixed network radio and telephone communications have interesting market structure implications. Fixed radio provides faster communications but it requires high geographic customer density. It is also cheaper when installed in mass. This gives it characteristics that are similar to the distribution system; it may be a natural monopoly. This could give the incumbent distribution company a significant technical and economic advantage in supplying advanced metering services.
Communications via Wireless Systems: A Brief Overview
Cell phones -Cell phone technology is advancing from strictly voice to supporting a range of