biffvernon wrote:The cost has got to be greater than the cost of wind generated electricity - if only we had greater installed capacity. We just had three days of continuous 5GW wind and now its dropped to four and a half. That will have been worth a lot of gas.
I have to doubt that but it depends on what wind installation is considered and the actual fuel cost of the LNG. http://www.eia.gov/forecasts/aeo/er/ele ... ration.cfm
Note that they are computing actual live cycle costs and are not considering any subsidies or incentives applied to wind or solar.
vt, I was writing about the cost of the gas that was bought this last weekend. The spot price peaked at 150 pence per therm, as opposed the recent run of 80 pence. Of course we don't know what price was paid to divert three tankers of LNG to the UK from wherever they would otherwise have gone but somebody must have outbid the Japanese on Friday.
(The BBC radio news has just said the current gas price is 91 pence/therm)
That table is interesting. I notice the capacity factor listed for gas generation is 87%. That does not fit well with the graphs at http://gridwatch.templar.co.uk/index.php that show the peak at almost 20GW but much of the day is under 15GW (75% of the peak) and at night it goes down to below 5GW. No way is that averaging anything like 87%. Explain that please.
biffvernon wrote:vt, I was writing about the cost of the gas that was bought this last weekend. The spot price peaked at 150 pence per therm, as opposed the recent run of 80 pence. Of course we don't know what price was paid to divert three tankers of LNG to the UK from wherever they would otherwise have gone but somebody must have outbid the Japanese on Friday.
(The BBC radio news has just said the current gas price is 91 pence/therm)
That table is interesting. I notice the capacity factor listed for gas generation is 87%. That does not fit well with the graphs at http://gridwatch.templar.co.uk/index.php that show the peak at almost 20GW but much of the day is under 15GW (75% of the peak) and at night it goes down to below 5GW. No way is that averaging anything like 87%. Explain that please.
That is not an 87% capacity factor. It is a cost in 2011 US$ per MMWH of delivered electricity. If you dig deeper they expect land based wind to be producing on average about 34% of the time. I don't know what their assumptions were for the long term prices of fuels like LNG but I doubt they used todays very low gas US price. It's in one of the side reports somewhere but I haven't had time to search it out. The point is that using the set of assumptions they chose Gas cost $ 65 and coal $100 for the same amount of electricity and off shore wind was all the way up to $221. What the UK's numbers are I don't know but without a lot of research nothing is certain.
1Costs are expressed in terms of net AC power available to the grid for the installed capacity.
2As modeled, hydro is assumed to have seasonal storage so that it can be dispatched within a season, but overall operation is limited by resources available by site and season.
Note: These results do not include targeted tax credits such as the production or investment tax credit available for some technologies, which could significantly affect the levelized cost estimate. For example,new solar thermal and PV plants are eligible to receive a 30 percent investment tax credit on capital expenditures if placed in service before the end of 2016, and 10 percent thereafter. New wind, geothermal, biomass, hydroelectric, and landfill gas plants are eligible to receive either: (1) a $22 per MWh ($11 per MWh for technologies other than wind, geothermal and closed-loop biomass) inflation-adjusted production tax credit over the plant's first ten years of service or (2) a 30 percent investment tax credit, if placed in service before the end of 2013, or (2012, for wind only).
Source: U.S. Energy Information Administration, Annual Energy Outlook 2013, December 2012, DOE/EIA-0383(2012).
Nope scrambled mess.
Trial #2
Added in the spaces. to put it back into columns
Trial #3 used periods.
Last edited by vtsnowedin on 25 Mar 2013, 22:32, edited 2 times in total.
biffvernon wrote:First column Plant type
Sexond column Capacity factor (%)
For gas it's 87 (I don't believe it for reasons above)
For wind it's 34 (which is a tad generous)
Ok now we are getting some where. just a coincidence that the levelized cost of wind in the last column is $86.8 and the plant capacity of natural gas is 87%. I thought you were confusing the two or I was confusing what you were getting at.
Why wouldn't a mechanical plant with a fuel supply be available 87% of the time? The crew shows up and flips the switch and the turbines begin to whine. A few weeks a year they shut it down go on vacation and grease the bearings etc. Probably starts out at 99% if staffing is available but needs more parts changes and overhauls as it ages hence the 87% lifetime average.
There's a difference between the time when the generator is working and the time when it might be able to work if it were needed.
I think we need to define what 'capacity factor' actually means or we'll just be comparing apples with pears.
As I understand it, capacity factor is the amount of electricity actually produced over, say a year, divided by the theoretical amount that might be produced if it were going at full tilt full time, times a hundred to express as a percentage. Or am I wrong?
Anyway, net change on storage in 24hrs to 6am today was -376GWh, but LNG was +588GWh, after those tankers arrived. Big flows from LNG into the network now, which I guess will need to stay there for some weeks...
biffvernon wrote:There's a difference between the time when the generator is working and the time when it might be able to work if it were needed.
I think we need to define what 'capacity factor' actually means or we'll just be comparing apples with pears.
As I understand it, capacity factor is the amount of electricity actually produced over, say a year, divided by the theoretical amount that might be produced if it were going at full tilt full time, times a hundred to express as a percentage. Or am I wrong?
I don't know. That sounds reasonable but some of these plants can and do vary there output to meet varying demand and I expect they count every hour it can deliver a load within it's design range as 100 percent for that hour. If that were not the case few would be above 65% due to daily fluctuations in demand. It's not the plants fault that everyone turns off the telly and turns in about the same time.
