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Power/Alternative Energy??

Identifying prospects in green power

Posted: 10 Jan 2013 ?? ?Print Version ?Bookmark and Share

Keywords:Piezo? mechanical vibration? thermoelectric generators?

The conventional methods for energy harvesting have been through solar panels and wind generators. However, new tools allow us to produce electrical energy from a wide variety of ambient sources. Furthermore, it is not the energy conversion efficiency of the circuits that is important, but more the amount of "average harvested" energy which is available to power it. For instance, thermoelectric generators convert heat to electricity, Piezo elements convert mechanical vibration, photovoltaics convert sunlight (or any photon source) and galvanics converter energy from moisture. This makes it possible to power remote sensors, or to charge a storage device such as a capacitor or thin film battery, so that a microprocessor or transmitter can be powered from a remote location without a local power source.

Market forces driving growth
Energy directives, rising operating costs and a growing green movement are driving adoption of WSN for energy harvesting applications. While previous WSN products (industrial machinery, agriculture, structural health monitoring) have left a fragmented market, cross industry efforts are underway to unify sensor networks with an IP-based platform to simplify development, attract new entrants and encourage innovation. Note: WSN can also mean wireless sensor node(s), thereby having either a singular or multiple configurations depending on its contextual use.

WSN is a disruptive technology that can deliver up to 80 per cent reductions in installation costs and support for a wide range of applications not possible with wires that make buildings greener and "smarter." With the prospect of installing sensors almost anywhere, buildings of any size can optimise their energy consumption, improve safety and security, and reduce operating expenses. Note that, in buildings, HVAC consists of two-thirds of current WSN installations, followed by lighting and access control. It is predicted that 15 million wireless sensor nodes will be installed within the next five years (Source: ON World Inc.) that will need to be either battery powered or powered by ambient energy, or possibly a combination of both.

In support of these growth projections, a recently published report from iRAP, Inc., EN105: Ultra low power (microwatt) energy harvesting for wireless switches and wireless sensor networking, the global market for ultra low power energy harvesting devices is estimated to have been $79.5 million in 2009. iRAP further estimates that the market will reach $1.25 billion in 2014, at an average annual growth rate (AAGR) of 73.6 per cent.

As a result, we believe that there is a very large market for products that address specific solution needs in the areas or renewable energy and energy harvesting.

Green power opportunities
Any products targeted towards green energy or energy harvesting will see growth opportunities in 2012 and beyond. Energy costs and environmental concerns, as well as the need to extend battery life for mobile devices, has resulted in a focus on power optimisation for a broad range of applications. Our energy-efficient products enable customers to convert power more efficiently, consume less power and extend battery life.

The market for portable solar-powered electronic devices continues to grow as consumers look for ways to reduce energy consumption and spend more time outdoors. Because solar power is variable and unreliable, nearly all solar-powered devices feature rechargeable batteries. Clearly, the goal is to extract as much solar power as possible to charge these batteries quickly and to maintain their state of charge.

However, solar cells are inherently inefficient devices, but they do have a point of maximum output power, so operating at this point is an obvious design goal. The problem is that the IV characteristic of maximum output power changes with illumination. A mono-crystalline solar cell's output current is proportional to light intensity, while its voltage at maximum power output is relatively constant. Maximum power output for a given light intensity occurs at the knee of each curve, where the cell transitions from a constant-voltage device to a constant-current device. Therefore, a charger design that efficiently extracts power from a solar panel must be able to steer the panel's output voltage to the point of maximum power when illumination levels cannot meet the charger's full power requirements.

Green power is not only limited to the generation of energy via energy scavenging, it is also symbiotic to using less energy to do the same function. One area where this is already having a significant impact is digital system power management. When digital power is done correctly, it can reduce data centre power consumption, shorten time to market, have excellent stability and transient response and increase overall system reliability, in networking equipment for example.

System architects of networking equipment are being pushed to increase the data throughput and performance of their systems as well as add functionality and features. At the same time, pressure is being applied to decrease the systems overall power consumption. In data centres, the challenge is to reduce overall power consumption by rescheduling the work flow and moving jobs to underutilised servers, thereby enabling shutdown of other servers. To meet these demands, it is essential to know the power consumption of the end-user equipment. A properly designed digital power management system can provide the user with power consumption data, allowing for smart energy management decisions to be made.

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