Residential Power Trading Will Depend on Wireless Sensor Networks
- Written by Melike Erol-Kantarci, Omar Asad and Hussein T. Mouftah
Wireless sensor networks provide numerous opportunities for smart grid applications including demand-side energy management, power system monitoring, coordination of plug-in hybrid electric vehicles and integration of renewable energy generators. Because of their low cost, intrinsic redundancy and ease-of-deployment, they will be useful on a large scale in power grids.
At the University of Ottawa, we have assembled a large team in a project called Wireless Heterogeneous Sensor Networks in the e-Society (WISENSE), combining expertise in wireless sensor networks and power engineering to develop applications and protocols for the smart grid.
Integration of wireless sensor networks (WSNs) into the smart grid opens a rich field of research with sensor web services as one fruitful area: It addresses the need to access data collected by a sensor network via standard interfaces and in common formats. Technology developed to that end provides for remote management, data collection and querying capabilities—capabilities that will be useful to the smart grid.
For instance, power consumption of home appliances can be measured by sensors and delivered to the smart phone of the user. The user can shut down appliances remotely, set a thermostat to start at a later time, or share consumption information with trusted communities. The consumer also can sell power generated by a roof-top solar panel or backyard windmill to the grid.
In the future, these applications promise to transform the electricity consumer from being a passive user into an active, power producing and selling user—an officially stated objective of the European Union, the United States and Canada, among others. (See for example the recent report of the Council of European Energy Regulators, "The Drive Towards Smart Grids".)
Ontario has one of the leading programs that enable home owners, farmers and small business owners to sell energy to the grid. Ontario's Micro Feed-in Tariff (MicroFIT) program, launched in 2009, provides renewable energy generators of 10kW or less an opportunity to contract with a local utility to sell energy for at least 20 years. Prices for electricity sold back to the grid are determined by the Ontario Power Authority and depend on the generation source. (Current rates are 80.2 Canadian cents/kWh for rooftop photovoltaics, 64.2 cents/kWh for ground-mount photovoltaics, 13.5 cents/kWh for wind, 13.1 cents/kWh for water power, 13.8 cents/kWh for biomass, 16.0 cents/kWh for biogas and 11.1 cents/kWh for landfill gas.)
Although consumers are not expected to become in aggregate large-scale suppliers of electricity in the smart grids of the near future, energy trading among consumers may contribute significantly to the power sources of some communities. Sensor web service technology will be an ideal tool for developing applications to residential consumers in such energy transactions.
The opportunities that become available with wireless sensor networks are not limited to sensor web services. WSNs can provide pervasive communications and control capabilities at low cost, which will make them an inevitable component of smart homes. Initially, smart homes mostly targeted inhabitant comfort and energy-efficiency, by helping adaptation to outside conditions. Next-generation smart homes will be designed with integration to the smart grid in mind.
In particular, demand-side energy management applications will be an integral part of smart homes. Heretofore, demand response has not been implemented for residential customers because the number of premises is so large, and because suitable communications and automation tools have been lacking. In the smart grid of the future, fine-grained demand-side management will be possible, thanks to communication technologies, intelligent devices and advanced control techniques.
In general, demand-side management aims to reduce the amount of power consumed and the total amount paid for it. At WISENSE and in the context of Ontario's MicroFIT program, we have introduced an in-Home Energy Management (iHEM) application, which monitors the power consumption in a smart home and allows the consumers to communicate with the home controller and negotiate a schedule for their appliances. The application takes into account what is the most convenient time for consumers as well as for the grid. Thus, if a user wants to turn on a dryer during peak hours, the home controller may suggest a different time.
Unlike most of the demand management techniques found in the literature, iHEM interacts with the user and the user is given the option to opt out from delayed start times. iHEM utilizes the pervasive communication environment provided by WSNs, making it possible to incorporate into daily routines energy management applications that are personalized and available anywhere and anytime.
WSNs are also ideal tools for monitoring the utility assets such as power lines, substations, wind turbines, and so on. With the integration of various generators and storage devices—flywheels, for example, and hybrid cars—status monitoring of the smart grid will require higher resolution than now; the effectiveness of automated decisions will rely on the robustness of the monitoring tools. This accounts for the attention WSNs are getting in industry and academia.