Energy import benefits of UK Solar PV

zeupater

PeterZ wrote: »

Now that we have to import increasing amounts of gas due to North Sea gas decline and the closure of coal fired plant, what are the benefits of PV due to reduced gas imports?

I think its highly likely that in the coming years we will see huge price increases in gas. If solar PV is reducing the amount of gas burnt at the power station then its reducing our imports and helping with the trade balance.

Anyone got any thoughts or numbers to play with?

Evening All

Looks like everyone's become set in the discussion again and is completely ignoring the original question, so let's put a simple stake in the ground to test the question ....

Okay, for the sake of sanity now let's just say that all electricity generation is gas based and British Gas is the sole provider. Looking at the cost of wholesale gas against the billed cost we find that BG calculate this as being 52% (2011 analysis)( http://www.britishgas.co.uk/youraccount/discover/your-bill/explaining-energy-bills.html ), therefore taking their average household usage of 14818kWh costing £555 ( http://www.britishgas.co.uk/youraccount/discover/your-bill/explaining-energy-bills.html ) the average cost per kWh must be 3.75p/kWh(555/14818). From this we can deduce that the wholesale cost of gas per kWh is 1.95p(3.75x0.52).

Right then we have a wholesale cost for the gas, now let's see what that means in terms of electricity. Let's say that the current conversion efficiency (gas to electricity) averages somewhere around 40% (based on full load efficiencies of OCGT 35%-42% & CCGT 55%-59%) ( http://www.ukerc.ac.uk/support/Gas ) and delivery losses over the grid averaging an additional 5% ( http://www.ofgem.gov.uk/Networks/ElecDist/Documents1/Sohn%20Overview%20of%20Losses%20FINAL%20Internet%20version.pdf ) - (Section 4.2) ..... so the wholesale purchase cost of fuel per kWh electricity consumed becomes 5.13p(1.95/0.4/0.95) .... this is the effectively the import cost.

Next, let's look at the total pv generation in the UK which would be offsetting the energy imports. Leaving aside the larger installations of 50kWp+ and looking just at system included in the FiTs scheme, we find that as of 6/3/2013 the total installed pv capacity was 1439175kW (1.44GW)( https://www.gov.uk/government/statistical-data-sets/weekly-solar-pv-installation-and-capacity-based-on-registration-date ), which, if averaging an annual 850kWh/kWp would generate 1.2TWh per year((1.44*850)/1000). Looking to a point in the future where there is (say) 10GW of capacity, which is well below Germany's current level, then 8.3TWh((1.2/1.44)*10) of generation would theoretically be displaced.

Okay, we have the data we need, let's now see what this means to the balance of trade .... At the current level of installation it's ~£61.6million((0.0513x1.2x1,000,000,000,000)/1000), at a 10GW penetration it becomes ~£428million ((61.6/1.44)x10) and if it was to reach the same level as it is in Germany today (32.66GW), then it would become ~£1.4billion ((61.6/1.44)x32.66) per year at current prices.

To counter this there would be an obvious argument that a proportion of the gas powerplants would need to continue to be operated as a spinning reserve, however, these plants would not be operated under load and would therefore be idling, in which case the fuel usage would be relatively low and the generating efficiency would be much lower than when under load .... I would assume this to contribute to a reduction in the above savings of somewhere around 5%-10%, therefore the adjusted figures reflecting a median 7.5% become £57million, £396million and £1.3billion per annum respectively.

I believe that the above represents a pretty decent stab at answering the original question posed.

HTH
Z

zeupater

antrobus wrote: »

Wouldn't you first of all have to find out where the various components of your PV solar system had been manufactured, in order to calculate the potential initial cost to the UK economy of importing them? I have no idea myself, but I wouldn't exclude the possibility that (say) the £5000 cost of importing the Chinese manufactured panels will generate an expected saving in reduced gas imports of only £2500.

Hi

I agree that this is a valid point, so linking this to my previous post let's see what the effect is .....

Okay, for this exercise let's assume that all of the panels and inverters are imported and absolutely none are manufactured in places like Wrexham, using glass from St Helens etc and that the vast majority of panels originate from China ....

Current spot-market panel prices for panels from China (as at Jan 2013) are €0.53/Wp ( http://www.solarserver.com/service/pvx-spot-market-price-index-solar-pv-modules.html ), which at current exchange rates is approximately £0.46/Wp. To this let's add an inverter which would likely be imported into the wholesaler at something around £400 for a ~3.6kWp inverter to be matched to 4kWp of panels, so the cost/Wp would be around £0.10/Wp (400/4000) ... the total cost of major component imports is therefore around £560/kWp ((0.46+0.1)x1000) at current economics.

Let's now simply make a comparison based on increasing the installation base by a nominal 10GWp ....

The cost of imports for 10GWp of installations would be ~£5.6billion ((560x10,000,000,000)/1000), which would save imports of gas of ~£396million (previous post) ...

At this point, to place the above into context, it should be noted that the UK currently operates a balance of traded good loss of around £9billion/month ( http://www.ons.gov.uk/ons/rel/uktrade/uk-trade/december-2012/stb-uk-trade--december-2012.html#tab-Key-Figures )

So we have a stab at another answer ... at current costs, the likely payback purely from a trade balance aspect would be ~14.1 years (5600/396) ..... however, panel prices are still falling (32.9% in 12months to Jan 2013) and international market gas prices are still rising ....

HTH
Z

PeterZ_2

zeupater wrote: »

Evening All

Looks like everyone's become set in the discussion again and is completely ignoring the original question, so let's put a simple stake in the ground to test the question ....

Okay, for the sake of sanity now let's just say that all electricity generation is gas based and British Gas is the sole provider. Looking at the cost of wholesale gas against the billed cost we find that BG calculate this as being 52% (2011 analysis)( http://www.britishgas.co.uk/youraccount/discover/your-bill/explaining-energy-bills.html ), therefore taking their average household usage of 14818kWh costing £555 ( http://www.britishgas.co.uk/youraccount/discover/your-bill/explaining-energy-bills.html ) the average cost per kWh must be 3.75p/kWh(555/14818). From this we can deduce that the wholesale cost of gas per kWh is 1.95p(3.75x0.52).

Right then we have a wholesale cost for the gas, now let's see what that means in terms of electricity. Let's say that the current conversion efficiency (gas to electricity) averages somewhere around 40% (based on full load efficiencies of OCGT 35%-42% & CCGT 55%-59%) ( http://www.ukerc.ac.uk/support/Gas ) and delivery losses over the grid averaging an additional 5% ( http://www.ofgem.gov.uk/Networks/ElecDist/Documents1/Sohn%20Overview%20of%20Losses%20FINAL%20Internet%20version.pdf ) - (Section 4.2) ..... so the wholesale purchase cost of fuel per kWh electricity consumed becomes 5.13p(1.95/0.4/0.95) .... this is the effectively the import cost.

Next, let's look at the total pv generation in the UK which would be offsetting the energy imports. Leaving aside the larger installations of 50kWp+ and looking just at system included in the FiTs scheme, we find that as of 6/3/2013 the total installed pv capacity was 1439175kW (1.44GW)( https://www.gov.uk/government/statistical-data-sets/weekly-solar-pv-installation-and-capacity-based-on-registration-date ), which, if averaging an annual 850kWh/kWp would generate 1.2TWh per year((1.44*850)/1000). Looking to a point in the future where there is (say) 10GW of capacity, which is well below Germany's current level, then 8.3TWh((1.2/1.44)*10) of generation would theoretically be displaced.

Okay, we have the data we need, let's now see what this means to the balance of trade .... At the current level of installation it's ~£61.6million((0.0513x1.2x1,000,000,000,000)/1000), at a 10GW penetration it becomes ~£428million ((61.6/1.44)x10) and if it was to reach the same level as it is in Germany today (32.66GW), then it would become ~£1.4billion ((61.6/1.44)x32.66) per year at current prices.

To counter this there would be an obvious argument that a proportion of the gas powerplants would need to continue to be operated as a spinning reserve, however, these plants would not be operated under load and would therefore be idling, in which case the fuel usage would be relatively low and the generating efficiency would be much lower than when under load .... I would assume this to contribute to a reduction in the above savings of somewhere around 5%-10%, therefore the adjusted figures reflecting a median 7.5% become £57million, £396million and £1.3billion per annum respectively.

I believe that the above represents a pretty decent stab at answering the original question posed.

HTH
Z

I would say that was an excellent answer to my question, thank you! The benefit to the UK economy is significant and will only grow as we import more gas that gets even more expensive.

I would argue that even if you ignore the environmental benefits, the economic benefits for the UK as a whole make PV a good investment for the long term benefit of us all.

Martyn1981

tberry6686 wrote: »

Most cars will move quite happily at idle and will use the same amount of fuel moving at idle that they will use idling while stationary but I accept the analogy is probably not the most appropriate.

I'm afraid I'd have to dispute this, 'idle' is not a set amount (think back to manual chokes), idle is varied to take account of different loading, such as warm start up on a summers day, or cold start up in winter, plus lights and rear demister being switched on. Also the modern engine management system will 'try' to prevent stalling to a small degree. Modern cars now idle nearer to 500rpm, whereas with less efficient fuel management systems they used to idle nearer to 1,000rpm to cope.

So the unloaded stationary idle, is not the same as a loaded moving idle, since the go faster peddle on the right is not the only variable to fuel consumption.

tberry6686 wrote: »

I won't argue that wind turbines can play a part in reducing emissions because it's obvious that they can. I will argue that solar panels will make at best a trivial saving on gas consumed in this country.

That was the point of my original post supplying a link to that article:

Martyn1981 wrote: »

As to gas savings, many people argued that having plants on tick over would burn just as much gas. Obviously PV is still very small in the UK, but as it grows, it's 'intermittent' impact would presumably be similar to that of wind power. Note, I'm not saying the scale of impact, rather that how PV generation and gas consumption interact, would presumably be similar to the interaction of wind and gas.

If so, then this article is quite important as it tried to show that there is a genuine correlation between wind generation and gas consumption. It's a little old, and the dates refer to 2011 (not 2012):

Obviously I'm concentrating on your gas reduction question, not gas plant reduction, since the role of PV is to help reduce the CO2 intensity of our generation, not to meet winter peak generation.

If wind generation and gas consumption are directly linked, as suggested, then surely the exact same correlation will exist between PV generation and gas consumption?

I completely admit that I'm assuming the same relationship for PV, and somebody may be able to point out why there is a 'clever' difference, but since I can't think of one, then surely the article (and other similar ones) also stand for PV, not just wind.

tberry6686 wrote: »

(I'm not saying they should not be used) but I do think the subsidies that are being given to both wind and solar power should be withdrawn and these industries made to stand on their own feet.

As long as this is done fairly, remember coal, gas (and oil) would have been far less efficient a long time back, so have benefited. They still benefit today as their true costs (pollution and CO2) emissions are not represented in their prices, so they do actually receive substantial subsidies, simply through failing to account for their true costs. Carbon costs are probably around 3p/kWh. Of note, carbon costs have just, this month, started to hit coal generation.

Nuclear also receives enormous subsidies, but these are 'hidden' in general taxation, which in itself distorts renewables subsidies since some of those subsidies aren't 'real' subsidies, but simply go towards leveling the price playing field.

Also remember that if we dredge up old news, nuclear was very heavily subsidised at the start by the need to produce weapons grade nuclear material. The heat used to power steam turbines was only a by-product!

To sum up, yes PV subsidies are still quite high, but they are now comparative to projected new nuclear subsidies, and costs are roughly similar to off-shore wind. Hopefully, by the end of the decade PV (domestic scale) will be comparative to on-shore wind, and gas/coal with CCS or carbon taxation.

So the subsidy is an investment for lower future prices. Or to go right back to Peter's original question, will help to off-set monies 'exported' to pay for foreign fuel, by using our own (free) fuel.

Mart.

zeupater

spgsc531 wrote: »

(1) That's wrong. A car requires more power to move, therefore must use more fuel to maintain revs (idle). Unless its going down a decline I suppose. If steep enough most modern cars will shut off fuel to the engine .....

....

MrsZ's car uses no power when stationary (idle), therefore much more power to move and if 'going down a decline' it uses negative power (ie, it fuels itself) ....

HTH
Z

spgsc531

zeupater wrote: »

....

MrsZ's car uses no power when stationary (idle), therefore much more power to move and if 'going down a decline' it uses negative power (ie, it fuels itself) ....

HTH
Z

The exception that proves the rule?

zeupater

spgsc531 wrote: »

The exception that proves the rule?

Hi

Not really ... it's just taking the 'rule' to it's ultimate extremes ...

Anyway, looking at a conventional engine, efficiency could be looked at two ways .... firstly in terms of fuel consumption per hour and secondly in terms of fuel consumption per unit distance covered. Whichever way is used, consideration must be given to the fact that the sole reason for a car's existance is to move passengers & goods, it doesn't really matter how efficient the engine is whilst idling because there is no distance covered, therefore the 'real' idling efficiency would always be zero% .... the period of idling simply has an effect on the overall efficiency in terms of overall mpg, so the level of fuel consumption when operating at zero% efficiency comes into play which is really the same as that of generating plant, which may be efficient when under significant load, but inefficient when not.

HTH
Z

spgsc531

zeupater wrote: »

Hi

Not really ... it's just taking the 'rule' to it's ultimate extremes ... (1)

Anyway, looking at a conventional engine, efficiency could be looked at two ways .... firstly in terms of fuel consumption per hour and secondly in terms of fuel consumption per unit distance covered. Whichever way is used, consideration must be given to the fact that the sole reason for a car's existance is to move passengers & goods, it doesn't really matter how efficient the engine is whilst idling because there is no distance covered, therefore the 'real' idling efficiency would always be zero% .... the period of idling simply has an effect on the overall efficiency in terms of overall mpg, so the level of fuel consumption when operating at zero% efficiency comes into play which is really the same as that of generating plant, which may be efficient when under significant load, but inefficient when not.

HTH
Z

(1) Inclusio unius est exclusio alterius.

I was just commenting on the OP post:

tberry6686 wrote: »

Most cars will move quite happily at idle and will use the same amount of fuel moving at idle that they will use idling while stationary

(But apparently not comedian's wife's cars)

zeupater

spgsc531 wrote: »

.... (But apparently not comedian's wife's cars)

Hi

On the contrary, what I have posted is entirely in accordance with your post of 22:34 yesterday and was meant to support it ..... perhaps it's just an example of where simple prejudgement should be displaced by a level of absorption, reasoning & understanding.

HTH
Z

grahamc2003

zeupater wrote: »

....

MrsZ's car uses no power when stationary (idle), therefore much more power to move and if 'going down a decline' it uses negative power (ie, it fuels itself) ....

HTH
Z

Unfortunately, both of those aren't necessarily the case. Once in Ready, you'll be using a parasitic 250W just sitting there ready to go. Also, it doesn't really matter whether you're going uphill, downhill or on the level - if you are calling for a lower level of acceleration than you are getting, you're likely going to be using regenerative braking. If you're on a slight decline and you want to accelerate, then you're likely to use positive power.

How are you finding it? Have you tried the heater yet?. if so, does it affect the state of charge much?