IET
Decrease font size
Increase font size
Topic Title: CO2 reductions due to wind power
Topic Summary: Is wind power failing to produce the promised reductions?
Created On: 16 January 2014 01:19 PM
Status: Read Only
Linear : Threading : Single : Branch
1 2 Next Last unread
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 16 January 2014 01:19 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

Is anyone willing to engage on the question: how much reduction in CO2 emissions can be attributed to UK wind energy?

There is now some 11 years of data published by government which can be analysed to give an answer to this. During this period the output from wind rose from almost zero to 4% of UK electricity generation. We might expect to see emissions due to wind reduce by an equivalent amount if wind is carbon-free.

There are five main reasons for changes in CO2 emissions: demand, changes in fuel-to-electricity conversion, changes fuel-to-CO2 conversion, changes in traditional fuel mix and renewables. This data can be found in The Digest of UK Energy Statistics (Table 5.6) and The Office for National Statistics' publication UK Environmental Accounts: Greenhouse Gas Emissions by Industry and Gas.

I have carried out 'what-if' analyses on excel to establish the contributions from these 5 reasons to reductions in CO2 emissions from 2000 - 2011 (latest CO2 figures available are 2011). To get a good average I did 16 comparisons between 2000 - 2003 and 2008 - 2011.

The conclusion is that wind-power contributes on average a reduction of only about 100 tonnes of CO2 per Gwh of generation output. Of the 4% contribution to output that's less than 1% contribution to CO2 reductions. This is also less than a quarter of the amount claimed by DECC and the wind industry and almost down to a fifth of what we would expect if wind was carbon free (around 470 tonnes/Gwh). What's going on here?

Has anyone else looked at the available data? Is anyone willing to check my method and figures?
 17 January 2014 08:31 AM
User is offline View Users Profile Print this message



ectophile

Posts: 546
Joined: 17 September 2001

Are you comparing like with like?

If the only source of CO2 were electricity generation, I would expect a 4% rise in wind generation to produce a roughly 4% decrease in CO2.

But there's also transport and non-electric heating to consider. Those will carry on generating CO2 regardless of how much electricity comes from wind.

-------------------------
S P Barker BSc PhD MIET
 17 January 2014 01:04 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

I've only looked at CO2 emissions from electricity generation (which include emissions directly relating to generation such as plant manufacture and maintenance, related transport etc) and , like you, would expect close to 4% reduction and was surprised to find such a shortfall.

Possible explanations could be:

1. Overestimating the output from wind plant.
2. Underestimating the losses between the plant and the consumer (e.g. transmission losses, maintenance etc., )
3. Additional emissions arising from the requirement to back up and balance an intermittent and unpredictable energy source with traditional plant running under sub-optimal conditions.
4. Inaccurate statistics - but they're the best evidence we've got.
 17 January 2014 01:23 PM
User is offline View Users Profile Print this message



ectophile

Posts: 546
Joined: 17 September 2001

In that case, I'd suspect that statistical uncertainties are a large part of it. Having spinning reserve would be another.

Also bear in mind that the generation displaced by the wind farms will be whatever can be turned off and on the most easily. That's likely to be gas, rather than coal or nuclear. So replacing 4% of generation with wind won't mean exactly a 4% drop in CO2.

-------------------------
S P Barker BSc PhD MIET
 17 January 2014 01:48 PM
User is offline View Users Profile Print this message



rogerbryant

Posts: 866
Joined: 19 July 2002

I have heard point 3 being mentioned a number of times. Excessive spinning reserves, part load operation and frequent starting of gas turbine systems were all predicted as absorbing a lot of the supposed benefits of wind power. For example:

http://www.civitas.org.uk/econ...ctricitycosts2012.pdf

http://www.telegraph.co.uk/ear...-wind-power-plan.html

http://www.poyry.com/sites/def...i-july2009-energy.pdf

Best regards

Roger
 17 January 2014 11:29 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

The statistical uncertainties seem to give consistently negative results for wind-power.

I agree, mostly gas generation will be displaced but does this account for such a large discrepancy? DECC settled on 430 tonnes of CO2 saved per Gwh of wind output having examined the displacement issue following a ruling from the Advertising Standards Agency. My results are showing a average of 100 tonnes/Gwh
 17 January 2014 11:37 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

There's a lot of surmising taking place in these papers/articles. I have looked at the empirical evidence (for what it's worth) and it points to a huge shortfall in CO2 savings from wind generation. If savings are really 100 tonnes/Gwh against the claimed 430 tonnes it will take more than 4 times the amount of wind generating plant to achieve the desired results than currently planned. Unless, of course the reasons for failure can be understood and compensated for. Can electricity storage or the 'Smart Grid' achieve this?
 18 January 2014 12:54 PM
User is offline View Users Profile Print this message



jarathoon

Posts: 1042
Joined: 05 September 2004

Is there anyone employed full time by the IET to help members deal with difficult and important problems like this (involving the interpretation of government statistics)?

I doubt whether your calculations are correct, but I am not sure the governments calculations or those of the ONS are either. The real truth lies somewhere in between I expect.

However the points you raise are important because we must keep in mind how much this all this investment in new energy generation infrastructure costs us all per tonne of CO2 saved; in pounds sterling, lost jobs and excess winter deaths etc. This is the main political motivation to raise prices in the short term (for rushing out new technologies before they are ready for the mainstream) and these are the figures that matter most and yet these are the figures most difficult to obtain.

In addition to the factors already stated above the figures are further confused by:
1. the change in the balance of gas to coal electricity generation in recent years.
2. the net decline in legacy nuclear energy generation over the period you study
3. the trend towards more efficient gas powered CHP systems as companies get priced off the grid (in the limit 80% efficient).
4. the false biomass CO2 accounting (cutting down trees that remove CO2 from the atmosphere, then manufacturing and transporting the woodchip half way around the world to burn in a different country)
5. the accelerating trend to export our energy intensive industries and jobs (that currently emit lots of CO2) as unilateral carbon taxes rise here. (the alternatively being apparently to subsidise energy intensive industries via a new energy welfare system to be started soon, funded by regressive levies on consumer energy bills)
6. the fact that exporting CO2 emissions abroad does not achieve anything in terms of global carbon emissions, but just acts to massage the UK only statistics.
7. the gradual increase in losses on the electricity grid and what to attribute these losses to. I would have thought that an increase in local solar energy should help to constrain grid losses, however moving more electricity greater distances, from North to South, seems to be having the bigger effect.
8. the cost transfer to the health service as more people become ill, because they cannot afford to heat and ventilate their house properly.


I had thought that onshore wind generation was the best of an expensive bunch in the UK; that includes solar, offshore wind, Generation III nuclear, tidal range and stream.

Now the government plans to subsidise everything, how do we know what investments make sense and what don't from an engineering point of view. If prices rise too high consumers and businesses, who don't have their electricity costs subsidised, will be motivated to detach themselves from the electricity grid; biggest users first.

Our politicians have turned into dishonest vote tarts riding wrecking balls - a recent controversial Youtube video (which I've never watch in full) seems to have inspired this thought. And we are increasingly turning into the hand maidens to dishonest vote tarts riding wrecking balls.


-------------------------
James Arathoon
 18 January 2014 02:18 PM
User is offline View Users Profile Print this message



jarathoon

Posts: 1042
Joined: 05 September 2004

There are day-night load changes over time associated with the UK's gradually reducing need for power relative to the nuclear baseload, as well as the increase in wind energy generation.

The ratio of dispatchable power needed between night and day varies over the course of a year and gradually from year to year. [i.e. net power needed to meet electricity demand once nuclear and wind has been subtracted from gross demand curve]. Some of this supply variation between night and day is being handled by coal stations (about 5GW at the moment), with the remainder (around 15GW of power variation) being handled by gas stations.

How does the ratio of gas to coal in the day-night net supply curve effect the overall efficiency of the system?

Also how do changes in the geographical distribution of wind generation play out and modulate this across the country?



-------------------------
James Arathoon
 20 January 2014 10:28 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

James, the stats I have referred to include details of the coal/gas/nuclear/oil/hydro/renewables etc mix in each year and I have accounted for the effect that changes in this mix have had over the period. And yes, it would be great if someone could check my figures.

There are of course many unknowns on both the energy supply and emissions sides of the equation which are not accounted for in the official stats. However if claims are made by the government and the wind industry they should be able to justify them and I suggest these stats are the best info we have at present.

And yes I would be very happy if someone would check my figures!
 21 January 2014 12:48 PM
User is offline View Users Profile Print this message



clivebrown

Posts: 21
Joined: 28 October 2001

Just a few thoughts; I haven't attempted the calc but as with just about everything else in life lots of others have tried and (surprise:surprise) there's lots of controversy.

Wikipedia ( http://en.wikipedia.org/wiki/L...ions_of_energy_sources ) gives mean life time CO2 emissions of Natural Gas 469g/kWh and Coal 1001g/kWh

Because both types of plant consume a lot of fuel during their working life time, the marginal CO2 emissions should not be much less than these figures.

On the interconnected grid power generated =power consumed (ignoring losses)
so any change of wind generation should cause a reverse change in the marginal thermal generation

So if coal fired generation is cheaper than natural gas (as at present) the MARGINAL CO2 saving due to wind will be less than when gas was cheaper (only a few years ago); and you get the (strange?) fact that the savings from wind will be least when the total system is most CO2 intense (i.e. coal cheaper than gas).
And thus - bizarrely - the TOTAL CO2 saved (by weight, not weight/kWh) when gas was cheaper and there was less wind generation could have been greater than it is now. All very confusing!

But the important point is that wind generation affects the amount of marginal thermal generation, so that the CO2 saved is at the rate of marginal rather than average thermal plant.

Hope this helps.....Clive

-------------------------
clivebrown
 21 January 2014 02:39 PM
User is offline View Users Profile Print this message



jarathoon

Posts: 1042
Joined: 05 September 2004

But as I said before the marginal change in power output is spread across coal and gas in a varying degree. The wind is changing at a slow enough frequency now (i.e. greater than a period of one day) that much of the wind energy may be being balanced by marginal changes in coal plant use.

Gas plants are being switched on and off daily, but how is the marginal change in the coal station output being controlled on longer timescales than a day? If all the coal stations continue to generate, then one possibility is that all the coal power stations share the reduction in load at a collectively shared cost to their generating efficiency.

Lets say there are 20 one gigawatt coal stations generating 20 GW of electricity for the grid at 1 tonne CO2 / MWh.

lets say 1 GW of wind energy arrives to the grid. In theory emissions should reduce to 0.95 tonnes CO2 / MWh if one of the coal stations is shutdown. Wind has saved 500 kg CO2 / MWh one twentieth of the carbon output.

However if all the 20 coal stations are modulated down in power, then what is the change in efficiency required to reduce the carbon savings due to wind from 500 kg CO2 per MWh to 100 kg CO2 per MWh?

Every coal station would then have to emit 995 tonnes CO2 for every 0.95 GW they generate. i.e. emitting 1005 kg CO2 per MWh instead of 950 kg CO2 per MWh. This change in carbon emissions could arise from a change in plant efficiency at the one per cent level given the 5% reduction in power output.

So are these sort of figures plausible?



-------------------------
James Arathoon
 21 January 2014 03:11 PM
User is offline View Users Profile Print this message



jarathoon

Posts: 1042
Joined: 05 September 2004

The average emissions figure (kg CO2 per MWh) depends on the size of the amount of wind energy used relative to the amount of fossil fuel energy used.

I suppose the better choice is to tabulate the emissions figures for coal and gas separately, and then try to see if there are any changes in efficiency and emissions in either that correlate with the varying amount of wind on the grid.

-------------------------
James Arathoon
 23 January 2014 01:59 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

Clive, DECC's 430 tonnes/GWh figure (per Gwh of wind output , if you insist!) is based on replacing gas primarily.
 23 January 2014 05:49 PM
User is offline View Users Profile Print this message



Ipayyoursalary

Posts: 265
Joined: 21 November 2009

Interesting discussion but rather academic when you consider global temperatures have remained flat for 17 years now according to RSS and UAH satellite records. This is despite a third of all man-made CO2 ever emitted having been emitted over that same 17 year period.

UAH Satellite Global Temperature Trend Since 1997

So why are we wasting £Billions 'decarbonising' our energy infrastructure with medieval wind & woodchip burners ? The question of whether we're wasting £Billions to save N molecules of CO2 or N/4 molecules of CO2 seems irrelevent: We're wasting £Billions on a non-existent problem.

Edited: 23 January 2014 at 06:29 PM by Ipayyoursalary
 23 January 2014 08:55 PM
User is offline View Users Profile Print this message



jarathoon

Posts: 1042
Joined: 05 September 2004

Originally posted by: Ipayyoursalary

So why are we wasting £Billions 'decarbonising' our energy infrastructure with medieval wind & woodchip burners ? The question of whether we're wasting £Billions to save N molecules of CO2 or N/4 molecules of CO2 seems irrelevent: We're wasting £Billions on a non-existent problem.


In regards to being able to predict next years weather, we are in much the same position as the Ancient Egyptians trying to predict how the Nile will flood the following year. They had oracle priests and other forms of divination, we have climate scientists. They laid out expensive and extravagant offerings to the God's, just as we still do today. [I suppose ours aren't completely without merit, you must admit onshore wind turbines do generate electricity cheaper than many other methods, now including new Generation III nuclear reactors]

For some reason the people in power like to be given the impression by those around them, that they are in full control of events, with an exceptionally privileged and intelligent view into the future; that, for example, children picking straws at primary school don't have . Because journalists would rather go to politicians for answers, rather than asking children to pick straws, they rarely attempt to undermine this collective delusion.

As in the past, what today's Rulers are being told about the future, is one vague educated guess after another; sometimes dressed up as divine knowledge, especially if enough has been spent on purchasing the guess or if enough vested interests see benefit in promoting the guess.

To cut to the chase and to mix my metaphors; the Pharaoh can eventually end up appearing in public with no clothes, on the basis of a guess that can later be easily proved wrong by a child (as long as they don't have too much schooling to blind them to this possibility).

That is the nature of the human existence: the great physicist and electrician Lord Kelvin produced various educated guesses using the best and most trusted physical theory then available to him and concluded that the earth must be much younger than 100 million years or so; in spite of all the geological and palaeontological evidence then available that seemed to prove this figure wrong. He was eventually and conclusively proved wrong, following on from investigations by a man with a photographic plate and a lump of uranium ore, and a woman shovelling and refining pitchblende. Who could have predicted that in advance?

Whether or not the anthropogenic CO2 global warming theory is correct or not, the way we have spent and are planning to spend our valuable resources as a society in trying to combat any potential long term threat is an utter disgrace. Our most recent energy policies are becoming extremely damaging and corrosive to the future of engineering culture in this country, because no one knows anymore what the true cost of energy should be. It is all the more embarrassing that the engineering leaders in this institution and other engineering institutions say nothing and do nothing to stop the irrational subsidy feeding frenzy from continuing.

With so many subsidies and protectionist policies flying about, we now need to create whole new schools of engineering to cope with this: like "Engineering using Subsidies", "Engineering at Any Cost" and "Post-Modern Engineering on LSD". Combined honours should also be available in ""Engineering at Any Cost, using Subsidies" to train up all the engineers needed on HS2, Generation III Nuclear and offshore windfarm projects.




-------------------------
James Arathoon
 26 January 2014 08:27 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

I like your thinking.

My knowledge on how the grid balances fluctuating energy sources is limited but I can see that very small reductions in efficiency in any one plant could soon multiply if several plants are modulated to cope with any one situation. Day-to-day costs of different fuels, the amount and rate of variability of the wind, and probably other factors too, such as the availability of imports and pumped storage, will lead the grid to draw on a range of different plant over any one period.

Thanks for your input Clive & James!
 29 January 2014 01:24 PM
User is offline View Users Profile Print this message



bluedun

Posts: 10
Joined: 12 January 2014

Any thoughts on losses in transmission. Could these be significantly underestimated? Official Stats seem to assume output = supply.
 29 January 2014 03:28 PM
User is offline View Users Profile Print this message



jarathoon

Posts: 1042
Joined: 05 September 2004

Originally posted by: bluedun

Any thoughts on losses in transmission. Could these be significantly underestimated? Official Stats seem to assume output = supply.


I am raising this question to the energy networks association http://www.energynetworks.org/

with the following email...


In the Digest of UK energy statistics (DUKES) chapter 5

https://www.gov.uk/government/publications/electricity-chapter-5-digest-of-united-kingdom-energy-statistics-dukes


e.g. from table 5.3 Commodity balances etc

There seems to be a steady increase year on year in the transmission and distribution grid losses. Do you know of publicly available research work into the reason for the year on year increase in electricity transmission and distribution energy losses? And also any work done to develop strategies either for reducing the losses or mitigating future rises?

The costs of these losses are set to increase dramatically over the next few years as more generators receive subsidies based on the electrical energy they supply to the grid rather than the electrical energy consumers and businesses are able to use from the grid.

Increasing energy losses, together with the increasing cost of those energy losses, may justify different engineering solutions at some point; for example a HVDC transmission spine running up the length of the country.


-------------------------
James Arathoon
 02 February 2014 01:22 PM
User is offline View Users Profile Print this message



westonpa

Posts: 1771
Joined: 10 October 2007

Originally posted by: jarathoon
It is all the more embarrassing that the engineering leaders in this institution and other engineering institutions say nothing and do nothing to stop the irrational subsidy feeding frenzy from continuing.

Obviously the 'leaders' do not see things quite as you do James, do you accept the possibility that they are correct and you are wrong? I would however argue in your defence that you publically give your opinions and you back them up with logical and well thought out arguments and yet the 'leaders' are always strangely silent. If I am honest I am not sure institutions have that much influence with governments who for the most part appoint committees around them and who are generally full of people who are a long way removed from the coal face (out of touch).

Regards.
IET » Energy » CO2 reductions due to wind power

1 2 Next Last unread
Topic Tools Topic Tools
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.