Background There is plenty of ambient energy in the world around us and the conventional approach for energy harvesting has been through solar panels and wind generators. However, new harvesting 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. Click here to check out Linear Technology's energy harvesting products to be used as potential solutions.
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 percent 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 optimize 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: Ultralow power (microwatt) energy harvesting for wireless switches and wireless sensor networking, the global market for ultralow 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 percent.
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. This is why Linear Technology has spent time and resources to develop specific products to enable viable and cost effective solutions today.
efficiency is always important.
Your available usable power is the product of efficiency and non usable (without tranformation) available power.
zero times anything is still zero
10% times anything only allows 10% of the energy use...
But I do understand why this is being framed in this way. If you are going to convert these types of power sources you cannot expect to get to conventional efficiencies considered norms in normal power suppl design.
Thus the lowered expectations framing of the issue.
The numbers in the Table for solar panel don't look right to me. With solar constant at ~1400W/m^2 and accounting for atmospheric attenuation, albedo, etc., let us say an insolation of 800W/m^2 which works out to 0.08W/cm^2. With solar panel efficiencies at 10 to 20%, this is few 10's of mW/cm^2, NOT few 100's claimed in the table.
The article otherwise a smorgasboard of Linear's solutions!
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