Eco Friendly Polytunnel heating

[martin95]

I would like to heat my polytunnel in an eco friendly way. My thoughts are to use a simple idea. My polytunnel would be heated in the normal way ie by the sun heating the air. I would then use a simple 'heat recovery' system of pipes to suck the air using a compter fan powered by a 12v battery riged to a PV solar panel. This warm air would be blown down to the bottom and the heat absorbed my some material.

Now that is where i am stuck. What material is good at absorbing heat and then releasing this energy as latent heat so that the poly tunnel can be heated a night therefore extending 'growin time'.

Any ideas guys.

Martin

[Turtle]

Originally Posted by martin95

I would like to heat my polytunnel in an eco friendly way. My thoughts are to use a simple idea. My polytunnel would be heated in the normal way ie by the sun heating the air. I would then use a simple 'heat recovery' system of pipes to suck the air using a compter fan powered by a 12v battery riged to a PV solar panel. This warm air would be blown down to the bottom and the heat absorbed my some material.

Now that is where i am stuck. What material is good at absorbing heat and then releasing this energy as latent heat so that the poly tunnel can be heated a night therefore extending 'growin time'.

Any ideas guys.

Martin

Inasmuch as polytunnels tend to low height, the soil itself is fairly efficient in storing the thermal energy. There is in this of course the matter of how much soil is exposed, which varies by the spacing and stage of growth of the plants. All in all, if you draw off any thermal energy during the day then you have deprived the plants of its benefit.