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Post by Nucular on Nov 15, 2012 8:33:04 GMT 9.5
Using the NREL LOCE calculator, I want to calculate the LOCE of a combined wind-gas (CCGT) baseload (90% overall capacity factor) powerplant.
Wind is supposed to contribute 40% to the overall production, natural gas 60%. Note that this is only going to be a very crude calculation, I want to see at what gas price it starts to make economic sense to add wind turbines to reduce gas demand.
Financial:
Period (Years): 30
Discount Rate (%): 5
Case 1: CCGT only
Capital Cost: $1100/kW
Fixed O&M: $44/kW
Heat Rate (Btu/kWh): 341200/55 = 6204
Case 2: CCGT+Wind
Wind at 20% capacity factor is to supply 40%: Wind needs 2x the nameplate capacity.
Capital Cost: $2000*2 (Wind) + $1100 (CCGT) = $5100/kW
Fixed O&M: $60*2 + $44 = $164/kW
Heat Rate (Btu/kWh): 341200/55 = 6204
now the next step is tricky. The heat rate for the wind turbines is obviously zero, because they consume no fuel. Is it therefore valid to estimate the overall heat rate of the combined system in the following way:
6204*0.6 (CCGT share of overall el. production) = 3722
?
This would reflect the 40% fuel savings through wind ... again note that this is only a very crude calculation.
It reveals that a combined wind-gas powerplant would start to outcompete pure CCGT power plants once the gas price hits $20/MBtu ($13.7/kWh for Wind/CCGT against 13.9/kWh for CCGT), provided my I got the calculation right, of course.
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Post by David B. Benson on Nov 15, 2012 11:35:10 GMT 9.5
In the US one cannot obtain longer term loans than 15 years for wind and 20 years for the CCGT. The fixed O&M for wind appears much too large to me.
As for your question, yes, that is correct.
Why don't you register and become a member?
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Post by Nuclear on Nov 15, 2012 22:39:51 GMT 9.5
Registered, much more convenient that way.  Assuming a 15 year payback time puts CCGT at an advantage even at a natural gas price of $20/MMBtu. In order to increase investments into capital intensive but more environmentally friendly generating technologies such as wind and nuclear, we need to find a way to provide low-interest loans with longer payback times to utility companies. The financial markets won't do it. I adjusted the O&M costs for wind to $35/kW-yr. So the total O&M costs for the Wind/Gas system would be $35*2 + $44 = $114 15y, 5% Discount, $20/MMBtu: CCGT: 14,5ct/kWh Wind (40%)/CCGT (60%): 15,3ct/kWh 25y, 5%, $20 CCGT: 14.3ct/kWh Wind/CCGT: 13.7ct/kWh How long will it take for the gas price to hit $20/MMBtu? In the EU, it may already happen by 2030. This would make integrated powerplants worthwhile if the financial conditions are right (and cheap coal or nuclear are frowned upon). In the US it will likely take much longer for gas to get that expensive, thanks to the shale gas boom. Carbon emissions of the Wind/CCGT plant: Wind: 10g/kWh CCGT: 500g/kWh 10g*0.4+500g*0.6 = 304g/kWh ... not really a game-changer, but better than nothing I suppose. |
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Post by David B. Benson on Nov 30, 2012 9:38:12 GMT 9.5
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Post by trag on Dec 1, 2012 3:13:54 GMT 9.5
I'm not. I expected them to be higher. Texas has enough wind generation to equal the energy actually generated by about two nuclear power plants. Texas has spent or will spend close to $10 billion on transmission lines to move the wind electricity. That's about what two nuclear reactors would cost. So if the transmission lines, alone, for wind cost the same as equivalent nuclear generating capacity, then the added cost per megawatt hour should be approximately the same as the cost of nuclear electricity. Which would put it somewhere in the ballpark of $100/MWHr. The EIA numbers for LOC of various energy sources are listed in a table, the text for which clearly states that the costs of backup power and power transmission are not include in the factors. These costs, for unreliables, add up to as much again as the generating capacity cost, for each of them. In other words, you buy wind three times. First you buy the generating capacity at a rate which might be competitive. Then you buy the transmission lines for a cost close to the cost of the generating capacity. Then you buy the back-up capacity and fuel which finishes tripling the cost. In the real world wind cost about three times as much as FF or nuclear and solar costs 4 - 5 times as much. |
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Post by David B. Benson on Dec 11, 2012 10:00:53 GMT 9.5
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Post by Roger Clifton on Dec 11, 2012 12:13:26 GMT 9.5
I quite agree. They say: "During the hours when there was not enough renewable electricity to meet power needs, the model drew from storage and, on the rare hours with neither renewable electricity or stored power, then fossil fuel. " So the plan requires gas turbines, sitting idle for maybe 90% of the time, paying interest to the bank rather than pay for adequate storage? If that really is a cost-benefit analysis, it underlines the fact that current storage technology is hopelessly expensive. Development of cost-effective storage is certainly needed for wind and solar, but also for decarbonised transport, small grids and eventually, aircraft. |
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Post by David B. Benson on Dec 11, 2012 12:27:04 GMT 9.5
Roger Clifton --- I suspect they have assumed that the natgas generators are completely paid for. Even so, units which are idle 99.9% of the time must charge a premium price (think US$90,000/MWh) when the units do actually generate.
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Post by edireland on Dec 11, 2012 14:54:21 GMT 9.5
Small grids are probably more likely to be solved in most cases by improvements in VSC HVDC technology (see HVDC Light and whatever the Siemens version is called... I can't remember off hand).
They are going to be powering a North Sea oil/gas rig complex from a shore installation.
Almost all places that currently make do with isolated microgrids are sufficiently close to a place that has or soon will need a full sized grid to make simply connecting them with HVDC practical.
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Post by trag on Dec 12, 2012 3:42:55 GMT 9.5
Well, if you read that Science Daily article, they based their conclusions on a complex computer model. You can pretty much massage those things to output any result you desire. However, assuming they did put in a decent effort, I bet they did not properly calculate grid improvement costs. From the blurb, it sounds like they just assumed the existence of sufficient grid at the outset.
Unreliables requires one to have massive grid capacity, because one never knows which source will be producing at five times its average capacity, so every source must have a massive transmission capacity available.
Any way you cut it though, their results are counter to real world experience, and the article does not give enough information to subject their methodology to review. They just hand waved that it is "a computer model".
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peterc
Thermal Neutron
Posts: 30
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Post by peterc on Dec 12, 2012 17:53:12 GMT 9.5
on the sciencedaily article:
The trouble is you get things like this thrown in your face if you argue that renewables can't do it.
The press take up these things avidly, and any second-rate scientist or institution that wants publicity only has to put out something like this (or like the Fukushima butterflies), and they get instant coverage.
I tried to get a closer look, but they demand 40$ for the paper, and I'm not going to give them my money. No doubt to really check it you'd need the complete computer model as well.
They seem to distinguish high/low/zero wind/sun regimes. For the low regime they seem to propose over-capacity and geographical spread to keep the fridge running. For the zero regime : storage, which includes hydrogen from electrolysis, and hydrocarbon back-up.
With all these factors and the network problems trag mentions above, checking the model promises to be interesting work.
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Post by trag on Dec 13, 2012 2:55:53 GMT 9.5
The trouble is you get things like this thrown in your face if you argue that renewables can't do it. The press take up these things avidly, and any second-rate scientist or institution that wants publicity only has to put out something like this (or like the Fukushima butterflies), and they get instant coverage. I agree. That is exactly the problem. That, and the fact that most folks don't have enough interest and/or education to be skeptical of these kinds of claims. |
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Post by David B. Benson on Dec 13, 2012 9:30:06 GMT 9.5
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peterc
Thermal Neutron
Posts: 30
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Post by peterc on Dec 13, 2012 18:00:55 GMT 9.5
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Post by trag on Dec 14, 2012 3:33:18 GMT 9.5
Hmmm. I think that the German Energy Agency may be vastly underestimating the cost of transmission infrastructure. They say they'll need 135,000 Km of new transmission line. That's about 85,000 miles. In the USA the cost of high voltage transmission line is at least $2 million / mile. That would yield a cost more like $170 billion, not the maximum of $55 billion that the agency announced. Of course, perhaps that 135,000 Km isn't all high voltage transmission line and the lower voltage lines are cheaper? Still, given Germany's performance to date, I bet they low balled the numbers. Their current situation suggests that they have systemic delusions in their institutions. |
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Post by quokka on Dec 14, 2012 11:24:28 GMT 9.5
They used a supercomputer for simulations.
Maybe time for a snarky remark. If they required a supercomputer to find this "optimum", the whole exercise may be over optimized and the optimum unstable with even small changes to input assumptions to the model.
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peterc
Thermal Neutron
Posts: 30
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Post by peterc on Dec 14, 2012 16:55:34 GMT 9.5
The level of over-capacity in the "successful" Delaware model is 290%.
What this translates into in terms of plastering the countryside (most of the capacity is onshore wind in the model) with giant asparagus (how they jokingly refer to the towers in Germany) is, for the time being, left to the imagination.
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Post by proteos on Dec 16, 2012 21:39:06 GMT 9.5
In the USA the cost of high voltage transmission line is at least $2 million / mile. That would yield a cost more like $170 billion, not the maximum of $55 billion that the agency announced. In fact I think this depends on the actual perimeter of 'high voltage lines'. The HV lines can be divided into categories. For example, it is planned to build/enhance 4000km of very high voltage lines (200kV+) in Germany. Estimated cost: $25bn. The DENA study includes 'normal' HV lines, which are cheaper. To get to 100 000 km, you have to include those, and they are cheaper than the 'very high' versions. |
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Post by proteos on Dec 16, 2012 21:56:49 GMT 9.5
The main finding is that ditching overflow is more economical than storage. I bet that only works when you have limited population density, though. And even then, I think this is not very credible from a business point of view. Having back up in the form of fossil generation will stay cheaper for quite a long time whatever happens than to have 3x overbuild. Besides, it also means that the electricity market will become a capacity based market more than an energy market. In case of overflow, prices will be negative, so no money will come from energy sales. And in a capacity market, fossil fuels are difficult to beat (OCGTs rule there!). |
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Post by David B. Benson on Dec 26, 2012 14:20:14 GMT 9.5
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Post by Nuclear on Apr 5, 2013 16:20:00 GMT 9.5
www.ceoe.udel.edu/cms/carcher/my_papers/mason_archer_RSER_2011.pdfAccording to this paper by Mason / Archer on firming wind output, a network of several interconnected wind farms in a Class 4 wind region in the US backed up by CCGT produce 216g of CO2 / kWh of firm power delivered. At a carbon price of $30 per ton of CO2 emitted, such a system would be competitive with coal at present-day US natural gas prices. While 216g/kWh is still too high for a true low-carbon system, it's still a significant step into the right direction when compared to coal. Such a combined system would be a real option for a country like Australia to replace ageing coal plants with. In the end (by 2050), even lower specific emissions would be required which could only be provided by nuclear or renewables with storage, but on the way to a low-emission future, natural gas is a viable bridge IMHO. In the end it's a political choice. Australia could go full-out nuclear now, but it would be a political non-starter, while wind/gas are acceptable now and provide meaningful emission reductions when compared to coal. My philosophy: get started on natural gas and wind now to start cutting carbon emissions rapdily, while preparing the public and the industry for a large-scale nuclear roll-out in the future.
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