Observing the world of renewable energy and sustainable living

Archive for the month “February, 2017”

Thermo-Acoustic Heat Pump


The Dutch national energy bureau ECN has build the prototype of a heat pump that is smaller than conventional heat pumps and potentially could become even a lot smaller. What is special about this heat pump is that it operates on sound. Sound is a pressure wave. If air is compressed it gets warmer. The ECN heat pump is a closed tube with speakers.

Core parameters: heat pump is a wall-mounted box of 40x50x10 cm. You need electricity for an air pump and speakers. Electricity of 1 kWh returns 4 kWh of heat. Air is pumped from outside and led through the (inaudible) “sound heat pump” and finally pumped into the living space, providing ventilation as an extra.

Within the Dutch context that means that you get the same heat performance from 2 kWh (40 cent) as from 1 m3 gas (64 cent). Eventually that heat pump can be powered by electricity from renewable sources. The heat pump should cost ca. $1,000 including installation.

[] – Warmtepomp van ECN wordt de nieuwe gevelkachel
[] – Thermoacoustic heat engine

At [1:00] the sound-heat conversion is demonstrated. Sound in the tube pumps heat from lower to higher temperatures.

The thermo-acoustic principle in reverse: use heat to generate standing sound waves and create mechanical work.

Hamburg Considers Large Scale Storage of Heat


The key challenge with setting up a 100% renewable energy base is providing storage facilities. This applies to intermittent supply of electricity via wind and PV-solar, that needs to be matched with equally intermittent demand. The same consideration applies to space heating, the demand of which currently is mostly covered via fossil fuel. If you want to phase out fossil fuel for space heating, you will need to get serious about seasonal storage of heat: trapping solar heat in the summer, use it to heat large bodies of soil and withdraw these Joules in the Winter.

The city of Hamburg is considering a large scale heat storage that should cover 25% of Hamburgs needs. For the moment the buffer would be charged with industrial waste heat from fossil sources. But once realized the storage bugger could be fed with thermal solar as well.

Estimated cost: 4 cent/kwh, half of the price customers currently pay for district heating.

[] – Hamburg considers innovative heat storage scheme


sse_figure28a_rev[source] Global potential for windfloat’s (infinite)

[] – Senvion nominated for first floating wind farm
[] – Floating wind turbine
[deepresource] – Gold Mine North Sea
[] – Drijvende windmolens in alle soorten en maten

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