From mobile phones to Wi-Fi, wireless communications have fundamentally changed human behavior. As the much hyped era of the Internet of Things looms, the dense, rich communication networks needed seem to only be possible using wireless networks. Moreover, big data requires ever more data to be collected and shared. In buildings, this means more sensors and more communications to enable better efficiency. Though wireless communications are poised to facilitate this transformation, the shift remains tangled in the wired status quo.
In addition to communications, building networks need power to create what Navigant Research has defined as nanogrids, which are, in essence, single-building microgrids capable of aggregating and optimizing distributed energy resources (DER) while increasing resilience thanks to their ability to island during utility power grid outages. Running power wires to sensors is costly in new construction and prohibitive in most existing buildings. As a result, it’s not done unless absolutely necessary. Wireless makes the communication side of the equation easily scalable. The incremental cost for connecting more sensors is small. But, if a sensor needs wired power, why would anyone invest in wireless communications? Power remains the key to unlocking greater data density in smart buildings, and thereby, expanding near-term opportunities for nanogrid applications.
One approach to reducing the cost of sensors is lowering the cost of power wiring rather than eliminating the wire all together. This is accomplished by using low-voltage direct current (DC) power for sensors, controllers, actuators, and even LED lighting. Low-power DC wiring doesn’t need to be installed by an electrician, reducing the installation cost. Also, many electronic devices are natively DC-powered. So alternating current (AC) power must first be converted, resulting in an efficiency loss. Moreover, onsite generation of power through solar PV panels or wind turbines is typically DC (as are battery storage devices). So, DC distribution within buildings helps match energy supply with loads (since according to some estimates, 80% of building loads such as LED lighting, laptops, and cellphone chargers are all natively DC). Low-power DC in buildings can serve as building blocks to nanogrids that tailor energy services to the precise needs of end users.
The push for DC power is being led by the Emerge Alliance, an industry association developing DC power distribution standards for commercial buildings. A competing solution can be found in Power over Ethernet. Both solutions can be cheaper to install than a traditional system. But, though low power is less intrusive than the status quo, wires remain a limiting factor.
Power from High Frequencies
Eliminating all wires is the most elegant solution to enable the transition to more data-rich buildings. Currently, this is being done either by installing batteries or by harvesting ambient energy to power devices. Batteries require replacement and, when examined on a cost per kilowatt-hour basis, are very expensive. They just don’t provide enough benefit to eliminate power wires. Energy harvesting, on the other hand, eliminates the maintenance requirement but is restricted by the ambient light available.
However, a shift from energy harvesting to wireless power transmission is on the horizon. Ossia, a tech startup, has demoed its Cota wireless power technology and expects to have commercially available products by the end of 2015. Cota works by broadcasting radio waves over the 2.4 to 2.485 GHz ISM band (the same as Wi-Fi, ZigBee, Bluetooth, and others) and is capable of transmitting about 1W of power up to 10 meters – enough for a sensor, but not much else. Even a decade from now, it’s unlikely that wireless power transfer or energy harvesting will be able to provide enough power for anything more than a sensor. But leveraging big data in buildings requires more sensors, many more than are currently deployed. Wireless power could be the building block that brings the Internet of Things to smart buildings and hasten the spread of nanogrids.
For a more detailed look at the nanogrid market, please join our free webinar, The Expanding Business of Nanogrids, on Tuesday, October 14 at 2 p.m. ET. Click here to register.
Tags: Distributed energy, Energy Management, Microgrids, Smart Buildings Program, Smart Utilities Program
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