By Harry Forbes, ARC Advisory Group
Several major US utilities are now going forward with Advanced Metering Infrastructure (AMI) programs. Some of these programs will enter the deployment phase in early 2009, where these utilities will each be installing several thousand new smart meters per week. Since these new AMI deployments cover the entire customer base, it will take several years for a large utility to complete its full deployment.
The occasion of new meter installations is an opportunity for these utilities to install a communications infrastructure that reaches into the home and supports future home-based smart grid applications. The most talked about applications are demand response (where certain customer appliances are duty-cycled to reduce utility peak loads) and support for optimized and intelligent charging of Plug-In Hybrid Vehicles (PHEVs).
While PHEVs are not imminent, the need to plan for them illustrates the dilemma now facing utilities. The new meters must have a 20-year life, yet the networking technology embedded in them is quite new. Normally, utilities would deploy such new technology very gradually, so that it could be field proven long before it reached most of their customers. The need to upgrade their entire metering infrastructure precludes using any such relaxed schedule. To support in-home applications, utilities have chosen ZigBee technology, and in particular the ZigBee Smart Energy profile, which was developed by the ZigBee Alliance in collaboration with US utilities to support home energy applications enabled by AMI.
Emergence of IP and CAP
Last month’s formation of the IPSO Alliance (IPSO standing for Internet Protocols form Smart Objects) showed that advocates of IP sensor networking are organizing to state their case and make their presence felt in the market. IPSO includes Arch Rock Corporation, Dust Networks, Eka Systems, and Nivis. Collectively these firms represent thought leadership in the wireless sensor networking space. The Alliance also includes Silver Spring Networks, a builder of IP infrastructure for AMI, and networking giants Cisco and Ericsson.
This week brought an announcement by Arch Rock of the Compact Application Protocol, or CAP. In a nutshell, CAP is an architecture that enables ZigBee applications and profiles to run over IP networks rather than the ZigBee networks, which they were originally developed for (and with). CAP is documented in an IETF draft that was published this month, and was demonstrated in prototype form at the 2008 Sensors Expo.
The announcement states that CAP “expands the scope of ZigBee applications to any IP-enabled device”. True enough, but another way to say this is that CAP preserves the upper layers of ZigBee (which utilities like) while replacing the ZigBee network layer with IP (which utilities also like). Given the 20-year duration of their technology bet on new meters, utilities are far more comfortable building IP networking into their AMI architectures. Until CAP, they could not extend IP into the home without giving up the ZigBee Smart Energy profile.
Powerline and Wireless Networks Needed
Another important benefit of CAP is the potential to unify diverse types of home networking. AMI home applications must reach from the electric meter to in-home devices, such as thermostats, water heaters, pool pumps, and (eventually) garaged vehicles. Choosing a single physical link to reach all these devices is problematic. Despite boosting their signal power, wireless networks are challenged by some locations of meters and home equipment. Utilities are more comfortable deploying a combination of wireless and power line carrier networking, but at present ZigBee applications must be wireless only.
Some utilities are now pushing the HomePlug and ZigBee alliances to develop a technological solution that will enable common communications for in-home applications over both types of networks. They have formed a new ad hoc working group, unaffiliated at present, that is driving to define such a solution. This group met last week in Vancouver. Their scope is limited to utility demand response and smart energy applications, rather than the broader field of home automation. CAP offers a relatively easy and appealing option to unify these communications. While some HomePlug devices support IP communications, most do not. ZigBee supports IP only to its network gateway. The vision of this group is that ZigBee Smart Energy devices could use either the wired HomePlug or ZigBee’s IEEE 802.15.4 wireless links. Furthermore, the use of IP opens the door to future addition of any other type of link that supports IP.
Given their AMI deployment schedules, the working group has laid out a very aggressive schedule. But as one participant in last week’s meeting told ARC, “The beauty of this group is that end user utilities are driving it, and they have the best hammer of all. They are the customer, and they have money to spend.” Despite the impending AMI deployments, CAP will likely have a big impact on AMI, and soon, since the technology has already been demonstrated, and the end users who are driving this effort need a solution immediately, if not sooner.