Re: Public perceptions paper

[dave andrews]

On 29 September 2011 15:05, Oliver Tickell <oli...@its.me.uk> wrote:

Here is Stephen Salter's original posting to the Google Geoengineering group that triggered the discussion, complete with link to Storm's original paper:

=================================

While a nuclear power station is working normally the main CO2 emissions 
are the plant operators driving to work or slipping out for a smoke.   
However quite a lot of oil is needed for mining, rock-crushing and fuel 
production.  At present this amounts to about one third of the CO2 
release of gas-powered plant but the ratio is strongly driven by the ore 
grade and hardness of the over burden.   The break-even point with gas 
happens when ore grades get to about 100 ppm.  At present rates of 
consumption this is likely to happen within the life of plant planned 
now but it could be sooner if there is a mad dash. 

I do not think anyone knows how much carbon will be released during the 
final clean up process but I am sure that it will not be zero. 

There is an analysis at       
http://www.stormsmith.nl/report20050803/Chap_1.pdf 

Stephen 

Emeritus Professor of Engineering Design 
Institute for Energy Systems 
School of Engineering 
Mayfield Road 
University of Edinburgh EH9  3JL 
Scotland 
Tel +44 131 650 5704 
Mobile 07795 203 195 
www.see.ed.ac.uk/~shs

=================================

--
Oliver Tickell
e: oli...@its.me.uk
p: +44 1865 728118
a: 379 Meadow Lane, Oxford OX4 4BL, UK.

On 29/09/2011 13:50, dave andrews wrote:

guys..can you send me a copy of the paper so i can forward it along with the email....thanks...Dave

On 29 September 2011 14:38, Oliver Tickell <oli...@its.me.uk> wrote:

Thanks Storm - that's great that we are agreed that there is an effect here (or rather, effects).

I did not even know that wind output is being run to earth to allow nuclear power stations to keep on operating. I guess that happens mainly on windy nights, when demand is low. This will obviously have a big effect on the claimed carbon benefits of nuclear power since while this going on, there is no carbon benefit at all for the MWh the nuclear power stations are producing.

I also note your other point. If I understand it right, it is that nuclear power stations, often far from centres of demand, put additional demands on the grid (raising infrastructure requirements and costs) and also presumably engender additional grid losses creating a wider gap between MWH generated and MWh utilised.

Would you be interested in pursuing these questions? You are obviously an authority on the subject and I'm sure that a further paper on this topic would be highly publishable and of widespread interest. I think it would be hard to tackle in one bite - maybe a first paper could try to identify all the factors that apply, and give rough estimates of the scale of the effect in each instance, and invite further work to refine the figures.

If you are interested, I would be very happy to work with you to take it forward.

Regards, Oliver.


On 28/09/2011 18:15, Jan Willem Storm van Leeuwen wrote:

Hi Oliver,

Yes, I agree with your remarks. Nuclear power needs a large 'spinning reserve', gas-fired of course, because the large unit capacity of NPPs, 1000 MWe or so. Apart from the planned outages, there are always unplanned, sudden outages of NPPs. These outages could last for many days, because NPPs are very slow starters. Moreover they cannot operate load-following., only in base load. If there's a large supply of wind power at a given moment, it could easily happen that the wind power is switched off the grid, to keep the NPPs running (as is done in the USA). Another issue is that a number of large NPPs require a heavy grid with large high-tension lines.

All these effects are increasing the hidden costs and are enhancing the specific CO2 emission of nuclear power. I did not include these CO2 effects in my analysis.

Regards,

Storm

Op 28-sep-2011, om 15:53 heeft Oliver Tickell het volgende geschreven:

Thanks Jan Willem. I rather thought these factors were not taken into account, as they were not mentioned. However they do nonetheless increase the carbon footprint of nuclear power.

One way, for example, is by increasing the amount of 'spinning reserve' that is needed - basically fossil power plants that are running in neutral, ready to pitch in if a nuclear power station suddenly switches out. This is not needed for gas turbines - or at least much less - owing to the far lower probability of sudden outages. Nor indeed for wind - while the output goes up and down, and so needs backup, it is predictable based on weather stats and does not need expensive spinning reserve.

Another way is that gas is MWh from gas are likely to be displacing coal fired capacity as they are brought in to meet daytime / evening demand. MWh from nuclear pitches in (and ducks out) whenever it feels like it, and is therefore more likely to be displacing gas rather than coal.

We must also remember that things will change as more intermittent renewables come onto the Grid. At times of high wind generation, gas stations will be taken off-line while nuclear stations carry on. So again, nuclear will be displacing coal rather than gas.

All these factors will reduce the avoided carbon associated with nuclear. To actually put numbers on it will need careful thought, access to the statistics, and some hard work.

I am copying this to Dave Andrews who may have some further thoughts.


On 27/09/2011 15:16, Jan Willem Storm van Leeuwen wrote:

Hi Stephen and Oliver,

I did not consider that kind of data. 

In the nuclear world several notions are used, capacity factor, availability factor, load factor and perhaps some more, not always well-defined.

For my analysis the world-averaged lifetime energy production is important. I use the load factor, defined as the ratio of the actually produced useful energy over the maximum possible production (at 100% capacity during 100% of the time). This ratio approaches about 0.82 world wide for nuclear power plants.

Regards,

Storm

Op 26-sep-2011, om 16:32 heeft Oliver Tickell het volgende geschreven:

These are all interesting figures. As would be historic data on these very questions. I wonder if they are available.

But even once you have them, there is then the question of determining the implicit carbon footprint that results - essential to compare the C-performance of gas vs nuclear. My guess is that we are looking at several percentage points.

Storm, is this something you have considered?

Oliver.

On 23/09/2011 15:45, Stephen Salter wrote:

Oliver

One useful number might be the warning time till shut down.  For tidal stream plant it is infinite, for waves a few days for wind a few hours but for nuclear it can be very short.  Torness had to be shut down recently because of jellyfish blocking the cooling ducts.

A second number might be the time till normal service is resumed.

Stephen

Emeritus Professor of Engineering Design
Institute for Energy Systems
School of Engineering
Mayfield Road
University of Edinburgh EH9  3JL
Scotland
Tel +44 131 650 5704
Mobile 07795 203 195
www.see.ed.ac.uk/~shs

On 23/09/2011 15:33, Oliver Tickell wrote:

Hi Stephen, Jan Willem,

I do not remember hearing any further on this - but the question remains important.

BTW I have since seen figures for nuclear CF and it goes up to .8 for Sizewell B and down to .034 for the worst of the AGRs, all of which are bumping along the bottom. Typically in UK more like 0.6 average than 0.7.

The key question remains the 'quality' of the CF not just its size. A CCGT may also have a CF of say 0.6 but that reflects the fact it is turned on to meet demand. The same CF in a nuke would reflect outages for refuelling, maintenance etc, independent of demand - and often including very sudden unscheduled stops requiring 1GW instant backup capacity.

This means that we need to find a way to address the 'quality' factor in CCGT output and the effect on carbon emissions avoided from coal. When a CCGT produces in it is likely to be displacing coal capacity (at peak / medium peak) whereas a nuke is more likely to produce at a time of low demand displacing more efficient, lower carbon plant. So this would have the effect of reducing the nuke's carbon displacement.

Your thoughts much appreciated, Oliver.
--
www.nuclearpledge.com


On 23/08/2011 14:32, Stephen Salter wrote:

Oliver

Actual output for nuclear is typically around 0.7 but the carbon debt was all incurred before operation and turning them off does not reduce it.  The carbon for the plant is all released before operation and if this is delayed we may ask if there is a carbon equivalent of interest. 

Let's ask Storm van Leeuwen.

Stephen

Emeritus Professor of Engineering Design
Institute for Energy Systems
School of Engineering
Mayfield Road
University of Edinburgh EH9  3JL
Scotland
Tel +44 131 650 5704
Mobile 07795 203 195
www.see.ed.ac.uk/~shs

On 23/08/2011 13:36, Oliver Tickell wrote:

Stephen, I was interested to see your recent post, below.

Reading the paper, there is something I am not clear about. A nuclear power station is typically on full blast all the time giving a capacity factor of 1 (except when it has to go off). However a gas plant will modulate its output according to demand, giving I would guess a typical capacity factor of say 0.6 (guess).

So, when the authors compare nuclear power and CCGT emissions, are they forcing the CCGT to have a CF of 1 like nuclear? If so this is to greatly exaggerate the actual CO2 emissions that you would expect from a CCGT.

Another factor to consider is that as we get more intermittent renewables like wind and solar PV on the grid, the effect will be to further reduce the CF of gas plant - since when wind is generating strongly, CCGTs will scale back their output. This will further reduce the CCGT's CO2 emissions

Regards, Oliver.


==========================================

Stephen Salter <S.Sa...@ed.ac.uk> Aug 23 11:58AM +0100 ^
 
Hi All
 
While a nuclear power station is working normally the main CO2 emissions
are the plant operators driving to work or slipping out for a smoke.
However quite a lot of oil is needed for more...

The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

--

Dave Andrews

K.E.N.T.
+ 44 (0)  755 265 9166

+ 31 (0)  631 926 885
+ 44 (0) 1225 837978

 

 

--

Dave Andrews

K.E.N.T.
+ 44 (0)  755 265 9166

+ 31 (0)  631 926 885
+ 44 (0) 1225 837978