By: Manas Saksena, senior director of technology, Smart-Energy Platforms at Marvell Semiconductor
Effective management of peak energy demand from the electrical grid holds considerable promise to improve efficiency and reliability and is a key goal and driver for Smart Grid developments. Utilities have to build their capacity to meet the peak demand loads in the system – which may only occur a few days per year. To address the peak demand loads, Utilities need powerplants that are available for peak-demand scenarios; however, there is significant cost related to construction, maintenance and operation of these peaking power plants.
The Utility goal of peak-demand management can be addressed through a variety of consumer engagement and Demand-Response Programs including:
- Engaging consumers by providing them timely information about their energy usage and costs and providing suggestions to reduce their energy usage.
- Implementing a dynamic pricing program to provide incentives for consumers to lessen their energy loads by either reducing their energy use during higher-price periods, or by moving some energy use tasks to times when the price is lower.
- Implementing more direct Demand-Response Programs whereby Utilities can reduce load on the grid by directly controlling devices inside a home over a Home Area Network (HAN). These programs are used on critically hot (or cold) days when peak loads are expected to occur, and enable Utilities to prevent brownouts or blackouts. Often, users are compensated financially to participate in these programs.
While all of these techniques are used and deployed today, mostly in small pilot programs, these efforts are still in nascent deployment stage with an unclear path for mass-scale deployments. One of the challenges has been the lack of a good standard for enabling communication between consumers or, more accurately, their devices.
The Smart Grid can enable and empower consumers to manage their energy consumption in coordination with their Electric Utility. And now the Smart Energy Profile 2.0 (SEP 2.0) is an emerging standard that is designed to enable informed consumer participation and implementation of Demand-Response Programs by the Utilities.
Smart-Energy Profile 2.0
The Smart-Energy Profile 2.0 is being developed to create a standard and interoperable protocol that connects smart energy devices in the home to the Smart Grid. While the original work for SEP 2.0 was done via a joint liaison agreement between the ZigBee Alliance and the HomePlug Alliance, the standard itself is designed to run over Transmission Control Protocol / Internet Protocol (TCP / IP) and is therefore media access control (MAC) and physical layer (PHY) agnostic. A new coalition of Alliances had been formed (composed of Wi-Fi Alliance, ZigBee Alliance, HomePlug Alliance and HomeGrid Alliance) with the intent of developing SEP 2.0 application level interoperability testing and certification program. Even though the standard is still under development, it is widely expected to be widely adopted by Electric Utilities to implement their consumer facing programs.
In addition to providing connectivity to the Smart Grid, it is also envisioned that self-contained implementations of Home Energy Management systems, which leverage SEP 2.0 application connectivity, will be deployed in the marketplace. Futhermore, SEP 2.0 enables the development and deployment of smart-appliances and services that not only provide energy related services, but also provide the ability for device OEMs and service providers to innovate and offer consumers enhanced user-experiences and value-added services.
SEP 2.0 Functionality
The SEP 2.0 protocol is built around the notion of function-sets and each function-set represents a minimum set of device behaviors required to deliver a particular functionality. Some of the core function sets defined in the specification include metering, pricing and demand-response load control (DRLC). These function-sets enable informed consumer participation in managing energy consumption in home and participating in the Utilities’ efforts to manage peak-demand loads in the Grid. Additionally, function-sets are being defined for more advanced use-cases such as Plug-in Electric Vehicles and Distributed Renewable Energy Management.
The metering function set allows devices to get usage-information from the smart-meter or any other device that has metering capability (e.g., a smart-appliance or a sub-meter). Thus, an SEP 2.0 compliant application running on a smartphone, tablet or a dedicated display device, could present to users real-time energy consumption information for the whole home. This information would be delivered directly from the smart-meter / indirectly from a cloud-based server, or from any smart-appliance or smart-energy device supporting metering function.
The pricing function set allows a Utility to send pricing signals to smart-energy devices such as smart-appliances and programmable thermostats. These devices can then take actions to reduce or shift usage when the energy price is high (based on pre-set user-preferences). Alternatively, the pricing signals may go to an energy management service, to store user-preferences and intelligently manage the energy consumption across multiple user-devices. Finally, an energy management service might seek user-input to initiate actions through any method that the user might want, such as email, short message service (SMS), voice alerts and others.
The DRLC function-set provides a more active means for Utilities to implement demand response programs where the DRLC events are targeted to specific devices and have expectations of specific load-curtailment (for example, set point offset for thermostats or duty-cycling for other loads). These programs are used when a Utility expects to hit peak demand, typically offering financial incentives to users to participate in these programs.
SEP 2.0 Architecture and Technologies
The SEP 2.0 application protocol is built on a representational state transfer (REST) architecture that is used widely to deploy Webservices over Hypertext Transfer Protocol (HTTP). A REST architecture is based on a client-server model in which servers contain and perform operations on resources. Servers expose resource representations to clients and clients make requests to access representations of resources on the servers such as read, write, create and delete. In SEP 2.0, resources represent things like meter reading, pricing tariffs, demand response events, etc.
SEP 2.0 resource representations are built to be compatible with the International Electrotechnical Commission’s Common Information Model (CIM). The result is an Extensible Markup Language –based (XML) protocol developed on a REST architecture utilizing HTTP for transport. In addition, the protocol uses other commonly used Standards. For example, it uses Multicast Doman Name System (mDNS) and DNS-Service Discovery to enable SEP 2.0 devices to be discovered on a local network implementing the service discovery method, popularized by Apple, through its Bonjour protocol and is now widely available on all major Operating System platforms from desktops to tablets to phones. Also, SEP 2.0 makes use of Transport Layer Security (TLS) to secure communications between devices, thus ensuring that the protocol meets rigorous security requirements needed to protect sensitive consumer information and to ensure integrity of Smart Grid transactions.
The SEP 2.0 architecture and the technologies used by the protocol standard are the same technologies that are used to implement the rich ecosystem of applications running on smartphones, tablets and browsers communicating with Web-based services. Thus, there is a broad-based developer community, know-how and tools to innovate around SEP 2.0 enabled devices. Similar to recent innovation in the mobile Internet world, SEP 2.0 enables technology that can quickly build and deploy cloud-based services. The only missing ingredient is the lack of widely available smart-energy devices implementing SEP 2.0 based communications.
Enabling Smart-Energy Devices and Services
A standard like SEP 2.0 only addresses part of the challenge as it still requires solutions to be built that overcome adoption barriers, engaging users and motivating participants. A prominent barrier for consumers is the availability of affordable solutions.
The easiest way to save energy is to not use it unless it is required. When users are away from their home, a significant amount of energy can be saved by turning off any electric / electronic devices that do not need to stay powered on and by changing the setpoints for thermostat and water heaters to energy-saving “away” mode. Heating / cooling and water-heater consume about 50 percent of energy in a typical home which can amount to significant savings for consumers.
While these actions can be taken with the existing mass-deployed devices, few users engage in these behaviors as they are inconvenient and compromise user comfort. For example, a user leaving home can set the thermostat to away mode, but will end up returning to a home that it either too hot or too cold for their comfort. Setting the hot-water heater to away mode would typically require a trip to the basement and it becomes a challenge to motivate users to do this in their busy lives.
Smart-energy devices that make it convenient for users to save energy without sacrificing comfort are a key ingredient to engaging consumers in managing their energy consumption. Consider a smartphone application that enables a user to set his/her thermostat and/or hot-water heater to “away” mode when they leave home and to remotely set it back to “comfort” mode so they can ensure that their home is at a comfortable temperature when they get back home. The simple, reliable, and affordable solutions are likely to engage users and are critical to mass-market adoption.
Offering Consumer Value beyond Energy Savings
The core technology to build a SEP 2.0-compliant appliance gives device manufacturers the opportunity to offer more consumer benefits, not just the prospect of saving energy costs. This is critical to mass adoption as it will provide consumers with other motivations to purchase smart-appliances and thermostats.
The first consumer benefit occurs by simply allowing applications to be developed on devices like smartphones and tablets that can interact with a smart-thermostat or appliance. Appliance manufacturers are under competitive pressures to provide more user-friendly interfaces, especially as they add more features to their appliances. This quickly gets expensive as technologies such as touch screen interfaces (which users are quickly becoming accustomed to) are expensive. Connectivity offers a solution to the appliance manufacturers as it can be used to provide consumers with rich user-interfaces on devices that they already own and provide a rich user-interface platform.
Beyond that, connected appliances enable an appliance manufacturer to offer a whole range of value-added services to consumers by having the device communicate with a cloud-based services using the technologies already present in a SEP 2.0 compliant software platform (HTTP and TLS client). For example, a water heater might be able to detect that it is about to leak and a service could send an alert to the user before the damage. Moreover, the owner of a smart-refrigerator might get a notification that the refrigerator door was left open, or the water filter needs changing. Cloud services could gather usage data from an appliance and present it to users through dashboards. They could analyze the data and present guidance to users on how to more effectively use their appliance, and when to do an upgrade. There are endless possibilities of value-added services and it is imperative that we leverage the SEP 2.0 protocol to ensure mass deployment of smart-energy devices.