Hacker News Reader

Comment by DrBazza | Hacker News Reader

Check my working...

The UK's national grid is currently running at about 35GW. A wind turbine, produces on average 1MW (from a potential 3.5MW with a 120m blade diameter). The turbines need to be spaced at 8x the blade diameter to be optimal, call it 1km. (edit)

So at the moment, the UK needs 35,000 wind turbines to match the national grid.

We'll need at least double that again to charge all electric vehicles in daily use if we get to 100% electric vehicles, e.g. only 5 million vehicles with 7kW chargers, but we have almost 30m registered vehicles in the uk.

That's almost 200km by 200km of wind turbines, or 120 miles x 120 miles right now.

No wonder we're putting them in the sea. I can't see all of Kent, Sussex, Surrey, Essex, London and Hampshire being covered with wind turbines somehow.

View on HN

I worked this out previously and came to the conclusion that electricity production needed to rise more like 50%. it was a while ago, but the vague calculation was something like this:

UK electricity consumption/year: 301.7 TWh

Miles driven per year in UK: 327e9 [1]

Convert into TWh if vehicle is petrol: 470TWh [2]

Electric cars need about a third the energy of petrol vehicles: 160TWh

See here: https://observablehq.com/d/e02d09be8794978c

[1]https://assets.publishing.service.gov.uk/government/uploads/...

[2] https://github.com/robinl/energy_usage

(Apologies some figures are not sourced)

Yep. That's why I think energy to fuel is potentially a better solution. It will also be a good fit for solar power, as you can just make then stockpile the fuel when the sun is out. For the UK though, I think most fuel would then be imported from sunny places.

I'm not sure that the UK will increase it's grid capacity enough to get all cars electric in the next 10 or 15 years. I have a feeling the UK will end up relying on interconnectors.

> I have a feeling the UK will end up relying on interconnectors.

Gridwatch used to allow you to download an entire year (or more) with a 5 minute resolution. Based on my last download from Sep 2018 to Sep 2019, a net of 7.6% of UK's electricity usage was from interconnectors

Not sure how much those brexit effects these, the UK government has ripped out the conditions that allow these to work, put all the blame on the interconnector companies, and still have no idea what the relationship will look like in 11 weeks time

https://www.gov.uk/government/publications/trading-electrici...

> Not sure how much those brexit effects these

Implicit auctions across the interconnector to end.

Also gridwatch isn't 100% accurate. Accurate enough to get a good picture though.

And if you want to download data, just download from elexon/bmreports. No point gong via a 3rd party.

Current electric cars are about 160 Wh/km.

327.0e9 miles = 526.0e9 km => 85 TWh.

You overestimated the efficiency of petrol vehicules by a factor of two :)

Note: heavy vehicules are 5% of miles travelled according to your [1]

Your info on capacity is a bit sketchy, the capacity of turbines being installed now is 8-10MW, with 15MW turbines on the roadmap. 3.6MW turbines were being installed 7-10yrs ago (exception being Rampion on south coast of UK being installed 2016/17)

Further offshore you go, and the bigger the turbine, generally speaking the better capacity factor you get.

Thanks. Cunningham's Law in action.

It's nonetheless interesting to see the scale of these. You can see them off the coast of Kent quite easily, but there's no perspective for the size.

The size is unbelievable to be honest. The 12MW system when constructed will be taller than the Eiffel Tower I believe, and that is the section above water, there will be 20-50m in water then considerable length piled into the ground.

The relationship between individual turbine capacity and the total power generation of a given area of land/sea is quite complicated. Bigger turbines don't get you as much additional power output as you might initially think because they have to be spaced out more. This is described in detail here: http://www.withouthotair.com/cB/page_263.shtml

(Of course, there's lots of space out to sea and larger turbines may be more economically viable)

Another way to see it : cars are parked about 95% of the time.

If you allow V2G for 5 million cars to deliver 7 kW each to the grid, they can power the country for about 7 hours with zero other mean of electricty production - assuming a 50 kWh battery in the car.

A 50 kWh car will power a typical home for a few days to a few weeks for energy efficient homes.

When full electrification of cars is done the grid will look very very different.

Even if you completely ignore V2G and look solely at load shedding via deferred charging if most of the energy requirements of the transportation sector were met with battery electric vehicles that's a massive chunk of power that can be deferred.

Demand at night is quite a bit lower than during the day and I suspect that's when most EVs will be charging - so that might help.

Agreed. I used a bit of lazy maths to make the numbers match to give a simple illustration. I suspect we'll have more than 5 million vehicles charging daily, and overnight, given that there's almost 30 million registered vehicles right now. And there's also 22kW chargers as well.

And year-on-year, everyone uses more electricity. Definitely interesting times ahead.

On top of that, energy expenses for air cooling and conditioning will increase dramatically in many places due to climate change.

So we probably need to triple the grid capacity. It's very hard to do that with renewables only without opening serious risks. Not impossible though. And will definitely take some long time to deploy the necessary facilities.

air conditioning is one of the smallest issues (somewhat ironically), as the demand from it is the highest when sun is shining, meaning there is lots of PV Electricity available (and with roof PV no burden on the grid either). Heat Pumps in Winter are the bigger issue generally.

I'm not so sure. If you're still speaking about the UK then we'd have to have a spectacular rise in temperatures to make AC a problem. The UK is much cooler than the USA and continental Europe in summer, so it's very rare to have AC at home.

I don't think I've ever seen a home with AC in the UK - certainly not here in Scotland.

Come to the south-east. New build homes down here are heat traps. We have two portable units for the summer and are going to get a full unit next year. We need it. Our house gets to 30C inside and stays at that through the night.

At least one of my neighbours has air-con that I can see, and a couple of re-builds in my town that I can see from the road have them too. My utterly unscientific estimate would be 1 in 500 houses in the SE now have aircon.

You're probably looking into heat pumps. We added one when we moved in and we got another 10 years out of the furnace. What killed the furnace was 27 years of moving air. And parts were no longer available to replace the "squirrel cage".

Heating the house with natural gas (from the replacement furnace) is now cheaper than using electricity, which is not what I predicted when we put in the heat pump. But I didn't foresee fracking.

Anyway, heat pump gets us hot air in the winter, cold air in the summer, and lowers our bills.

A neighbor put in a well-based (as opposed to air, like ours) heat pump which I was very interested in. But it took them 3 days of drilling (rocky soil) and tens of thousands of dollars. So probably just as well.

I did some calculations on how much more renewable the UK would need based on demand over a given year, and how much storage.

With 20 times the current renewable, 1GWh of charged storage, and a perfect grid, starting on Sep 18th 2018, we'd be fine until September 30th at 18:15.

With 10 million EVs acting as a battery store, all topping at 50KWh and going as low down as say 25KWh, that would be 250GWh of storage, we'd last until September 30th at 19:30.

That doesn't count the extra demand of the EVs in actually driving.

If we had 50 times current renewable and that 250GW of storage we'd be OK.

> Demand at night is quite a bit lower than during the day

Germany currently has around 60 GW, during the day we had 77 GW:

> https://www.electricitymap.org/zone/DE

To give a reference in France an average vehicule is driven 13000 km/year which is around 2 MWh with typical 150 Wh/km.

A parking spot is around 2.5 x 5 meters, solar panel efficiency is about 20%, in France we get about 1000 hours equivalent full sun per year so a parking spot covered with solar panels will produce 2.5 MWh each year.

Of course not enough in december and too much in june, but that gives an easy figure to remember.

Solar panels don't produce that much energy but electric cars are very efficient devices.

Another statistics about France : there are about 2 to 3 parking spot per car in the country.

I guess the car charging will make up a lot less than 35 GW constant demand though heating will probably make up a lot more than that over time. This will probably more than offset the general energy savings in electromobiles. Progressively you want to transition most of heating to heat pumps (COP of 3.0 should be quite possible) rather than direct heating, such as oil ovens and such (COP of basically < 1). Practical heat pump motors usually run on electricity and maybe natural gas but probably not heavy oil, coal or even wood. Also insulation of private homes will probably improve a lot in the coming years. It is a very complicated matter that is frequently occluded by politics in some form. It is nice to have interesting facts being mentioned, e.g. I didn't know the 8x blade diameter distance figure.

> So at the moment, the UK needs 35,000 wind turbines to match the national grid.

Assuming a 100% capacity factor which is far off the realistic value of around 30%.

Nuclear power plants have >90% capacity factor and therefore the most reliable power plants we have.

That's why China is building a lot of new NPPs (https://pris.iaea.org/PRIS/WorldStatistics/UnderConstruction...).

Reply on news.ycombinator.com