Renewable Energy II: Liechtenstein Post

Renewable energy sources are mainly the Sun, Wind and Water. Today's conventional energy sources may exhaust one day but renewable energy is not depleted upon usage. It is natural, harmless, economical and good for the environment.

Liechtenstein Post has issued two series of renewable energy stamps, one in 2010 and the other in 2011..  Below is the second series of renewable energy stamps.  I heard that they used Thermochromic ink in this stamp and if you apply heat on the area, the colour will change. 

But I couldn't see the change at all.  I purchased it from Liechtenstein Post directly.  Is there anything like only in miniature sheet it will work or any other hidden thing.  If anybody know the answer please clarify.

15th June: Global Wind Day

15th June is observed as Global Wind Energy Day. Wind Energy Day was first observed by the EWEA (European Wind Energy Association) in the year 2007,But in the year 2009 when the GWEC ( Global Wind Energy Council ) joined hands with EWEA ,Wind Energy Day was observed globally as Global Wind Energy Day.This occasion is used to spread awareness on Wind Energy.

Wind Energy is the energy generated by wind mills,turbines etc with the help of wind. National wind energy associations and companies organise various events in different parts of the world.

The below stamp was issued in the year 2004 in India for the occasion of Wind Energy:Renewable Energy Day.