Best use of renewable energy to heat

scoobyscotlad

We are about to commission a 200kw turbine on the farm and are seriously considering swapping from oil central heating to an electric boiler.
Imported electricity will cost us approx. 11p and export will be approx. 5.2p.
if we can use our own electricity, costing us approx. 5.2p, surely this should be cheaper than oil?
Some way of alerting us or switching on an electric boiler when generating our own electricity would be helpful also.
Grateful for any suggestions
TIA

Smiley_Dan

Wow 200kWp!

Maybe a heat pump to better leverage the input power? Not suitable for all (or, even, most) properties.

You can get devices which divert excess power, in your case you could have one heating an electrical immersion coil in a thermal store.

penrhyn

How does you're own electricity cost you any money?
In the middle of winter when its freezing and there is no wind how are you going to heat the farm?

lstar337

scoobyscotlad wrote: »

We are about to commission a 200kw turbine on the farm and are seriously considering swapping from oil central heating to an electric boiler.
Imported electricity will cost us approx. 11p and export will be approx. 5.2p.
if we can use our own electricity, costing us approx. 5.2p, surely this should be cheaper than oil?
Some way of alerting us or switching on an electric boiler when generating our own electricity would be helpful also.
Grateful for any suggestions
TIA

IIRC, Oil is about 6-7p/kWh.

But wind power is very variable, so any time you are not generating you will be paying 11p.

You need to work out the ratio of 'generating' to 'not generating' and apply that to your consumption of 11p units and 6-7p units.

IMHO, there is not enough of a drop in price over oil to cover the amount of 11p units you will consume, but that is really a guess.

Your best bet would be to connect both oil and your generated leccy into a thermal store, and only have the oil kick in when the leccy is not on enough. You can get diverting units that allow you to make the most of when you are generating.

You may get more answers on the green and ethical section of the board.

Andy_WSM

penrhyn wrote: »

How does you're own electricity cost you any money?

If they're using it locally to run an electric boiler then they're not exporting it, hence, not getting paid for it - so the "cost" is income lost really.

Smiley_Dan

Yes, I would imagine the export on an installation like this would be metered!

scoobyscotlad

Correct, the cost would be the lost exportable income.
But also, do not wish to be heating water at 11.2p if not generating our own.


A thermal store utilising both oil and own generated electric sounds interesting.


And yes, metered both import and export for this size of installation.
Being a dairy farm, milking and cooling the milk takes a significant amount of electricity which we hope to cut down on importing.
And off course, export a fair amount also.

WestonDave

There are a number of products around that have emerged along with solar power systems which detect when surplus solar is being generated and switch on an electric immersion element. Have a wander over the the Green/Ethical part of the forum as there are plenty of threads on there about using intelligent switches etc. OK so you are wind powered rather than sun powered but the essence will be the same in that you need something that can tell when you are exporting and divert it to uses on site.

scoobyscotlad

Thanks for that, sounds exactly what I had in mind!

captainhindsight_2

Your best option would be to install a ground source heat pump, this is worthwhile even without generating your own electricity. You would need to oversize you radiators and maybe add some insulation but there are grants/cashback for this anyway. And with the RHI payments gives about a three year payback, my house a 6 bed farmhouse is generating £9400 a year for 7 years and it cost £24,000 to install. Unfortunately we couldnt get planning for a wind turbine

scoobyscotlad

Just to add to the mix, we also "extract" heat from the milk produced and can currently heat water to 50c as we cool the milk with no additional cost, effectively free hot water.
Passing the return gas through a coil in a copper cylinder, thus helping the efficiency of the compressors and heating the water at the same time.
So we have a tank of 50c water approx 35m away from the main farmhouse.
Thinking it would take little extra electricity input(turbine generated) with a 3 phase element to get this up to 65-70c.
How then could we incorporate this into the central heating system just in front of the oil boiler?
TIA