Wind

[Taff]

Ok has anyone installed a small single wind turbine, I have seen a few about mainly on farms. I’m thinking if I could install one of these would it provide enough power to charge an electric car? Probably charging through the evening

[Stewpot]

Intuitively, I feel that's not going to work out.

 

Hunting around the web, I find that the Tesla Model S has a battery capacity of 100kWh (smaller cars are available). If you had a 10kW turbine working continuously at nominal capacity, and we ignore inefficiencies and energy losses in the recharging system, it would take 10 hours for a full recharge - in reality, probably two or three times that. And in a domestic setting, a 10kW turbine is pretty big.

 

Depending upon how many miles a day you do, and how windy it is at your place, that sounds a bit marginal. And a turbine of that size is likely to cost several tens of thousands.

 

Sorry to dampen your enthusiasm. An electric bike should be eminently do-able like that, though.

[ProDave]

Depends what you mean by "small" 

 

"Small" to most people would mean about 1kW which is not going to add much charge to your car at all.   10kW is probably more like what you need and they are not cheap.  You also need to be in an exposed location with few local obstructions to get the best out of them.

 

At some time I will play with a small turbine but I know our site is far from ideal so I am not expecting much.

[Jeremy Harris]

Electric vehicle charging presents some hard limits on the power source, unfortunately.

 

The lowest rate at which an EV can charge from AC is 6 A per phase, so about 1.4 kW from a single phase supply, or about 4.2 kW from a three phase supply.  If less power than that is available the vehicle will stop charging. 

 

The highest rate that an EV can charge at from AC is usually about 32 A per phase, so about 7.4 kW from a single phase supply.  Few cars have three phase onboard chargers that are capable of handing 32 A per phase, though, so often the three phase charging limit is significantly lower than 32 A per phase (my Tesla can only accept 16 A per phase from a three phase supply, for example).

 

The other issue is that car onboard chargers need to have the available current signalled to them, so a variable power source, like a wind turbine, would need something to measure the available generated power at any instant and communicate that to the car via the signalling interface.  The effectiveness of this depends on the response time of the car onboard charger (this can be tens of seconds) relative to the rate at which power generated by the wind turbine varies over time.  It's very probable that the car onboard charger may not be able to respond fast enough to cope with gusts and lulls in the wind.

 

Buffering the wind turbine output, by using it to charge a bank of batteries directly, then only generating 230 VAC from the battery supply, would be an option that may work OK, but it would need a fairly large battery bank, in order to be able to charge at a reasonable rate.  The battery bank would iron out the peaks and troughs from the wind turbine, so as long as the mean power generated slightly exceeded the lowest vehicle charge rate then it should work.  Whether it makes financial sense is debatable, though, as electricity is pretty cheap (costs me a bit over 2p/mile to run my car, charging with off-peak electricity).

[Taff]

Hmmmm thanks guys for all your detailed explanations, we are quite exposed and can be quite gusty at times. I hadn’t even considered the peaks and troughs of the wind. Ill end up waking up to head off to work with a flat battery ?. Aiming to keep long term costs to a minimum I guess the initial outlay would obliterate any long term gain. we will have 2 phase which I think I could run one feed to the garage to charge the cars overnight (going to look at the economy 7 option). Then the other feed to the house and ASHP. Well that’s what I think I could do? Jeremy 2p per mile, what sort of racing are you on?

[Jeremy Harris]

29 minutes ago, Taff said:

Hmmmm thanks guys for all your detailed explanations, we are quite exposed and can be quite gusty at times. I hadn’t even considered the peaks and troughs of the wind. Ill end up waking up to head off to work with a flat battery ?. Aiming to keep long term costs to a minimum I guess the initial outlay would obliterate any long term gain. we will have 2 phase which I think I could run one feed to the garage to charge the cars overnight (going to look at the economy 7 option). Then the other feed to the house and ASHP. Well that’s what I think I could do? Jeremy 2p per mile, what sort of racing are you on?

 

 

We have an Economy 7 supply, and the tariff at the moment is 8.148p/kWh during the off-peak 7 hours (at the moment from 00:00 to 07:00) and 15.729p/kWh peak rate.  The car tends to use roughly 250 Wh/mile, and I charge it mainly overnight at this time of the year, as our PV system is only now beginning to start generating appreciable amounts of energy again.  1 kWh gets me roughly 4 miles of range, hence the ~2/p/mile cost.  From this month onwards there's a good chance that I'll be able to charge the car from excess PV generation, so the "fuel" element of the running cost will probably drop to close to zero for maybe the next 6 to 8 months or so.

[Taff]

So I’m guessing the E7 solution is probably a good choice for me, we have no PV installation, this may be something that we might have to look at but aware that feed tariffs are coming to an end after sometime in 21. Hence I was initially thinking how can I provide energy.

[Jeremy Harris]

The Feed-in Tariff ended a couple of years ago, so there's now no subsidy for installing either PV, wind or small scale hydro generation.  All that may be paid for is the metered export of excess generation back to the grid, at a rate of around 5.5p/kWh, I believe.  To get this means having a smart meter installed (not an option at the moment for anything other than a single phase supply) and signing up to one of the companies offering the payment.

[Taff]

Oh we are just about to install our ASHP on a two phase, I was under the impression if we get it commissioned this year we would beat the cut off point. Please tell me I can ?

[Jeremy Harris]

The Feed-in Tariff  scheme stopped accepting new applications in April 2019: https://www.ofgem.gov.uk/environmental-programmes/fit/applicants with some exceptions.

 

The RHI scheme is still extant for heating provided by heat pumps etc.

[Taff]

Ah I was getting confused, easily for me that is!

phew ??