Solar ... In the news

paul991

I agree with what you say but shouldn't we be aiming to cover every roof top with pv especially large govt  buildings and solar canopies like this. https://www.aviva.com/newsroom/news-releases/2020/11/aviva-opens-one-of-the-uks-largest-solar-initiatives/

ABrass

Fields are cheaper than roofs. The return is better. They're also bigger and simpler.

So if you're an energy company trying to generate energy you will build on fields. Not on roofs.

Roofs are complicated and more expensive, and if you don't own the building you rent then the process and finances for installing solar on the roof to get the benefit is complex.

If you want to install on roofs then you need to talk to Blackstone and BlackRock to get it into their ESG plans. Or get laws requiring PV on all new industrial building roofs or a suitable penalty to allow installation elsewhere.

70sbudgie

ABrass said:

.... or a suitable penalty to allow installation elsewhere.

Like preventing installation on low quality agricultural land?

I understand that current technology enables ~3MW of PV per acre. 

Should be looking at what crops can be grown on type 3b land and therefore displaced. I don't know where to find the information, but have an idea that it may be livestock feed quality?

Imho growing crops as bio fuel is greenwashing. Especially as there aren't many crops rich enough in oil that can be grown in the temperate UK. I will have to look up your post @QrizB

Roofs may be more expensive to install PV than fields, but they have the added benefit of being a lot closer to demand. It is a better engineering solution. Even if it isn't a better commercial solution.

Edit to improve grammar

ABrass

70sbudgie said:

ABrass said:

.... or a suitable penalty to allow installation elsewhere.

Like preventing installation on low quality agricultural land?

I understand that current technology enables ~3MW of PV per acre. 

Should be looking at what crops can be grown on type 3b land and therefore displaced. I don't know where to find the information, but have an idea that it may be livestock feed quality?

Imho growing crops as bio fuel is greenwashing. Especially as there aren't many crops rich enough in oil that can be grown in the temperate UK. I will have to look up your post @QrizB

Roofs may be more expensive to install PV than fields, but they have the added benefit of being a lot closer to demand. It is a better engineering solution. Even if it isn't a better commercial solution.

Edit to improve grammar

It's not hard to find, harder to C&P with formatting  You're broadly right.

4.4 Subgrade 3a – good quality agricultural land
high yields of grass which can be grazed or harvested over most of the year
Land capable of consistently producing moderate to high yields of a narrow range of arable crops, especially cereals, or moderate yields of crops including:
cereals
grass
oilseed rape
potatoes
sugar beet
less demanding horticultural crops

4.5 Subgrade 3b – moderate quality agricultural land
Land capable of producing moderate yields of a narrow range of crops, principally:
cereals and grass
lower yields of a wider range of crops

Each acre can host about 0.3MW of panels.

The O2 is 104,634 m2, or around 25 acres. That's good for 7.5MW of panels if it were flat. 7.5MW is tiny for a modern industrial system.

Jeremy Clarkson has a 1,000 acre farm. He could have 300MW of panels on that land. Is it going to be easier to negotiate the use of 40-80 O2 arena sized buildings or one farmer's uneconomic land?

Retrofit Solar panels on roofs is elegant, but it's a bad engineering solution, because a good engineering solution is one that you can sell.

thevilla

Imho growing crops as bio fuel is greenwashing

The recent "everything electric" podcast about h2 had a more positive view.  When all cars are electric then the 10% of petrol which is now biofuel could be diverted to the tricky issue of decarbonising aviation.  Makes perfect sense imop that we can't do everything at once but we could have a plan for arguably the hardest of all.

michaels

thevilla said:

Imho growing crops as bio fuel is greenwashing

The recent "everything electric" podcast about h2 had a more positive view.  When all cars are electric then the 10% of petrol which is now biofuel could be diverted to the tricky issue of decarbonising aviation.  Makes perfect sense imop that we can't do everything at once but we could have a plan for arguably the hardest of all.

How does biofuels compare in land use to PV to make green hydrogen.  I would not be surprised if the PV solution was order of magnitude lower land use?

zeupater

70sbudgie said:

[ ... ]

Should be looking at what crops can be grown on type 3b land and therefore displaced. I don't know where to find the information, but have an idea that it may be livestock feed quality?
[... ]

Hi

Probably a little better than grazing ... it's likely suitable for a number of crops but it comes down to how much investment it's going to need to raise the yield to provide a reasonable return.

One of the local farmers has ~5MW of PV on a field which is probably graded as 3b(ish) that was occasionally used for crops (linseed/rapeseed/sugar-beet etc) in periods when fertiliser prices made it possible, but the sandy soil on that part of the farm simply needed too much annual investment as whatever was added each year simply leached away from the top layers where it was needed to support the crop. Most of the time the field in question was alternated between beef cattle & silage/hay for winter feed, but nowadays it's just solar & sheep & a few years ago he told me that the annual return from the same land (sheep vs cattle) was ~50% higher, although there was far more work involved with looking after around 4x-5x more sheep than the previous cows, equating to ~8-10x as many animals over a 2 year period (To sale: beef ~2 years vs lamb <1year) .... if it wasn't for the additional income from hosting the PV he would have stuck with cows and had an easier life, especially in springtime!  

HTH - Z

thevilla

michaels said:

thevilla said:

Imho growing crops as bio fuel is greenwashing

The recent "everything electric" podcast about h2 had a more positive view.  When all cars are electric then the 10% of petrol which is now biofuel could be diverted to the tricky issue of decarbonising aviation.  Makes perfect sense imop that we can't do everything at once but we could have a plan for arguably the hardest of all.

How does biofuels compare in land use to PV to make green hydrogen.  I would not be surprised if the PV solution was order of magnitude lower land use?

Well according to the podcast green hydrogen will never be used in aviation,  in fact unlikely to be used any distance from where it is made.  It also required 3 X the energy to make the h2 compared to the energy returned. 

I won't re state all the discussion around green h2 but it's well worth a watch.  Enlightening and hopeful.

https://youtu.be/JlOCS95Jvjc

michaels

thevilla said:

michaels said:

thevilla said:

Imho growing crops as bio fuel is greenwashing

The recent "everything electric" podcast about h2 had a more positive view.  When all cars are electric then the 10% of petrol which is now biofuel could be diverted to the tricky issue of decarbonising aviation.  Makes perfect sense imop that we can't do everything at once but we could have a plan for arguably the hardest of all.

How does biofuels compare in land use to PV to make green hydrogen.  I would not be surprised if the PV solution was order of magnitude lower land use?

Well according to the podcast green hydrogen will never be used in aviation,  in fact unlikely to be used any distance from where it is made.  It also required 3 X the energy to make the h2 compared to the energy returned. 

I won't re state all the discussion around green h2 but it's well worth a watch.  Enlightening and hopeful.

https://youtu.be/JlOCS95Jvjc

Yes but if PV on a piece of farmland returns 10x as much energy as growing biofuels then even losing 2/3rds of the PV energy producing hydrogen still means you need less land for PV H2 than you do for biofuels.

Of course if H2 is inherently unsuited to aviation then the energy output per acre argument is moot.

(A quick google suggests that a 1ha pv farm could generate 800MWh of electrical energy a year - 270 MWH converted to H2? -  whereas a hectare of sugar beet used for bio-ethanol might produce 33MWh of energy per year.  Which is more efficient use of land?!)

Martyn1981

michaels said:

thevilla said:

michaels said:

thevilla said:

Imho growing crops as bio fuel is greenwashing

The recent "everything electric" podcast about h2 had a more positive view.  When all cars are electric then the 10% of petrol which is now biofuel could be diverted to the tricky issue of decarbonising aviation.  Makes perfect sense imop that we can't do everything at once but we could have a plan for arguably the hardest of all.

How does biofuels compare in land use to PV to make green hydrogen.  I would not be surprised if the PV solution was order of magnitude lower land use?

Well according to the podcast green hydrogen will never be used in aviation,  in fact unlikely to be used any distance from where it is made.  It also required 3 X the energy to make the h2 compared to the energy returned. 

I won't re state all the discussion around green h2 but it's well worth a watch.  Enlightening and hopeful.

https://youtu.be/JlOCS95Jvjc

Yes but if PV on a piece of farmland returns 10x as much energy as growing biofuels then even losing 2/3rds of the PV energy producing hydrogen still means you need less land for PV H2 than you do for biofuels.

Of course if H2 is inherently unsuited to aviation then the energy output per acre argument is moot.

(A quick google suggests that a 1ha pv farm could generate 800MWh of electrical energy a year - 270 MWH converted to H2? -  whereas a hectare of sugar beet used for bio-ethanol might produce 33MWh of energy per year.  Which is more efficient use of land?!)

Yeah I get where you are coming from, just a theoretical comparison/exercise, that still comes back to PV, no matter what route is taken / product is chosen. Effectively  

So looks like the impact of PV on UK agricultural land, especially 3b, is minimal to negligible, even if it was scaled up massively (5x?). It will probably never get close to the amount of land used for golf courses/related uses.

I've always been a fan of demand side PV, as the running costs are minimal, and the value is higher (retail v's wholesale prices). But I really see no issue with lower grade land being used for PV farms. I think it's just the new thing being blown out of proportion, as per those extremely low percentage figures you posted a couple of days ago, on the amount of land being used, which are almost a rounding error.

...... and then add in what Z says about co-locating with grazing, and all boxes are ticked again, including (possibly) the longer term soil quality which should recover a bit over the 20(ish) years.