NISKAYUNA, N.Y.--People first touted the Internet refrigerator as a way to access the Internet from your kitchen. Now General Electric has found a more practical use for the networked fridge: the smart grid.
GE hosted a media day on the smart grid on Tuesday at its research lab in upstate New York, where it announced its net-zero energy home project and showed off this "kitchen of the future." Rather than let humans browse the Web, these networked appliances talk to smart meters in order to be more energy efficient.
Appliances can shave owners' bills in a few ways, cued by a "price signal" sent by the utility via the meter. If electricity rates go higher during peak times, appliances can go into conservation mode and dial down their consumption. Or these appliances decide to do their mode power-hungry tasks, like making ice, at off-peak times.
The "central nervous system" for a network of smart appliances is GE's Home Energy Manager, a device for programming device preferences. Seen here is the interface for a consumer. The system acts as a central communications hub between networked appliances and a home smart meter.
GE is looking at different options for accessing the system, including connecting to a home router so consumers can see energy information in real time, said Natarajan Venkatakrishan, director of research and development at GE Appliances. Individually, he said, GE's smart appliances can be more efficient by taking advantage of off-peak rates and by going into low-energy mode during peak times. The Home Energy Manager, which will cost between $200 and $250, collects data on multiple appliances.
The way that a smart clothes dryer works is that it gets a "price signal" from a smart meter that peak prices are in effect. If a consumer has set up the dryer to work with demand response programs, it will go from using two heating coils to one.
In a demand response program, the utility will offer the consumer a lower rate for dropping its energy use during peak times. The low-energy dryer mode will take 60 or 75 minutes, rather than 35 minutes. Consumers can also schedule to run dryers and other appliances in the middle of the night or other off-peak times.
Lowering energy use on high-energy appliances, such as clothes dryers and water heaters, can make a significant difference in aggregate. About 250,000 homes running their electric dryers is the equivalent to 600 megawatts of electricity use, about the same as one coal plant, said Venkatakrishan, who is pictured here.
GE's demand-response refrigerator can make adjustments to its settings based on peak-time price signals from the utility. It can also reduce its consumption significantly just by deciding when to run the defrost cycle to remove ice from a fridge's coils.
Right now, refrigerators defrost based on how often the door is opened and closed, GE executives explained. Energy use can be cut dramatically simply by running the defrost cycle, or making ice, in the middle of the night when demand for electricity is low.
GE executives said it's hard to say exactly how much its demand-response appliances will save consumers because prices vary across the country and many utilities don't yet use time-of-use pricing. One of these appliances, which will cost about $10 more than a regular GE model, can reduce its consumption on the order of 20 percent, they said.
What makes a smart appliance smart? On the right is a module that GE has developed that allows communications with a home's smart meters. The networking can be done in a variety of formats, such as the wireless Zigbee standard.
When GE releases its demand-response appliances next year, the module will be fitted onto the appliance's motherboard.
At its research center in Niskayuna, N.Y., GE has set up a smart-grid research center where it is working on various aspects of making the grid more efficient and reliable.
Here, electrical engineer John Kern runs a simulation of the smart grid in action. In this case, there's a spike in demand because it's a hot day and the added air conditioning load is straining the local distribution grid.
Behind Kern is the software that a utility would use to forecast the projected load and steps it can take to deal with it. In this case, it's going to try to "shed load," or lower power consumption in its local area. It sends a signal to buildings with a smart meter to indicate that it needs to reduce consumption. Reducing the load through efficiency is less polluting and less expensive than relying on "peaker plants" to meet high demand.
When this home dryer, which is equipped with a communications modeule, receives the peak-load event signal from the utility, it goes into a low-power mode, as shown by GE electrical engineer Owen Schelenz. It will take longer to dry the clothes but the consumer should get some sort of financial discount for participating in the demand-response program.
GE already makes smart meters with two-way communications between the consumer and the utility. There are a number of different networking paths that a utility can use to aggregate and transport information back to its data center. In its lab, GE is testing a WiMax system for communication from a home back to a utility. There are 140 million electric meters in the U.S. Converting a large number of them to smart meters will take about 10 years, GE executives said.
Another important piece of hardware in a smart grid are servers for handling the flow of data between the utility and its customers. One of the biggest technical challenges is processing and making sense of the huge amounts of data being gathered.
In addition to networked appliances, utilities also envision putting sensors along transmission lines and communications gear, such as routers, in substations. Here are two servers for managing policies during a demand-response event and for managing the electricity distribution system.