Monthly Archives: March 2010

Tiny generators harvest energy from natural motions

The Parametic Frequenzy increased Generators (PFIGs)  could produce enough electricity from random, ambient vibrations to power a wristwatch, pacemaker or wireless sensor. They are highly efficient  at providing renewable power from arbitrary, nonperiodic vibrations. The generators have demonstrated that they can produce up to  0,5 miliwatts ( or 500 microwatts) from typical vibration amplitudes found on the human body. That is more than enough energy to run a  wristwatch which needs between one and 10 microwatts, or a pacemaker which needs between 10 and 50.

 The energy-harvesting devices were  created by Khalil Najafi,  and Tzeno Galchev, experts of electrical and computer engineering. They have built three prototypes and a forth is forthcoming. In two of the generators, the energy conversion is performed through electromagnetic induction, in which a coil is subjected to a varying magnetic field. This is a process similar to how large-scale generators in big power plants operate. The latest and smallest device which measures one cubic centimeter, uses a piezoelectric material, which is a type of material that produces charge when it is stressed.

 ‘Batteries are often an inefficient way to power the growing array of wireless sensors being created today’ said Najafi. ‘ They  have more limited abillities, because the rely on regular, predictable energy sources.  But these tiny generators  are working  in environments of traffic driving, on  a busy street or bridge or in a tunnel, machinery operating and people walkin up and down stairs, for example.  This kinetic energy surrounding us every day does not occur in periodic, repeatable patterns.

The ultimate goal is to enable various applications like remote wireless sensors and surgically  implanted medical devices. These are long lifetime applications where it is very costly to replace depleted batteries or worse to have to wire the sensors to a power source.

Bloom box hype or breakthrough?

‘Energy in a box’ so describes K.R. Sridhar, CEO of Bloom Energy, his new invention. The Bloom box is a new kind of fuel cell, which produces electricity by combining oxygen  in the air with every kind of fossil, such as solar energy, propane and naturel gas. About ten years a Bloom box is  sufficient to provide every modern house for electricity.

There is still not much known about the ‘new fuel cell of the future’. Bloom Energy is a bit mysterious about the technology.  But we already know  that  the core element of this technology is sand, from which  fuel cells are being  manufactered.  There is no combustion and the chemical reaction is efficient and clean.  In stead of using  the device generates oxygen.  

The energy which Bloom Eenergy generates is not cheaper than the energy in the  power plants. The cost for generation one kWh electricity is six to eight cent, compared to four euro cent by European power plants. Yet the consumer profits more  from a Bloom Box, because there are no service costs and electricity transportation costs. At this moment the price of a large Bloom energy server is 700.000 to 800.000 dollar, but within five to ten years there are smaller Bloom boxes which shall have a price less than 3.000 dollar.

Is the Bloom box a hype or a breakthrough in the industrial energy ? Critics assert that, if Sridhar succeeds  to make the technology affordable  and efficient , that it is easy for other companies to copy this. There are some questions which have to be answered such as; how long will the fuel cells  last? And is application with solar energy or biomass possible? And what is the reaction of the power plants, would they reject the Bloom box or are they willing to sell them?