|
|
Post by Scottish Scientist on Apr 25, 2015 6:45:23 GMT 9.5
Modelling wind turbines and pumped-storage hydro for renewables-only 24/7 electrical power
This Scottish scientist produced a spreadsheet model of an electricity generating system composed primarily of wind turbines backed up with pumped-storage hydro-electricity schemes. Such modelling can predict how much wind power and pumped-storage energy capacity should be installed for satisfactory renewables-only generation.
Click to view a larger image
The spreadsheet line graph above plots power & energy variables for the time-line modelled –
• curves for power exported, demanded, from wind, for pumping, from the hydro-turbine &
• a curve for the energy stored by water pumped into the upper reservoir.
The time-line graphs data for the grid in Scotland, normalised in proportion to wind power and demand data for June 2014, as downloaded from the Gridwatch Database of the U.K. National Grid Status Website.
Modelling assumptions for this graph –
• the peak demand in Scotland in 2014 was 6GW
• an installed maximum wind turbine power in Scotland of 33GW = 5.5 x peak demand
• an installed pumped-storage hydro energy capacity in Scotland of 160GWh = 1.11 peak-demand-days
• the pumps have a maximum power consumption of 6GW = peak demand
• the hydro-turbines have a maximum power output of 6GW = peak demand
• the pumps and the hydro-turbines both have an efficiency of 88%
• no other power stations are generating power.
I conclude that such models will help to take the guesswork and uncertainty out of renewable-energy electricity system design!
Click to view a larger image
A real electricity system which had adopted wind power and pumped-storage hydro for future electricity generation would inherit existing power stations which could continue to serve on stand-by as a further back-up, reserve or emergency power supply.
UPDATE
Discuss in my Scottish Scientist blog - Modelling of wind and pumped-storage power
|
|
|
|
Post by eclipse on Jul 26, 2015 9:07:52 GMT 9.5
Or we could build dispatch-able nuclear for truly CO2 free power generation in a real emergency. Here's a question for you, Scottish. What do you propose we do about replacing petrol and diesel? If we're so busy backing up intermittent wind and solar just to run our power system, don't we have to build far more plants (like about 6 times as much capacity according to your Scottish graph) just to 'recharge' the hydro dams ready for the troughs? What if we just built nukes to run all day every day, which would give us the night time spare capacity (according to Americas NREL) to charge about half of our cars at night as well? It's just that I keep hearing renewables advocates contradicting each other. 1. We're all going off grid, and magical storage devices are going to back up wind and solar on our own houses or industrial estates or offices in town. 1. We're all going ONTO a continent-wide super-grid, and it's going to cost $10 billion in its own right to build and is an important backbone of the grid as we get wind and solar from Perth when there's a drop in wind and sunshine in Sydney or Cairns or whatever. 2. We're going to charge about half our electric cars at night on excess nighttime spare baseload power supply when business closes down for the day! (NREL) 2. We're NOT going to really do anything at night because... who needs power at night? Amory Lovins says the requirement for baseload electric power is a myth, and there's no real need for power at night. (Except for charging iphones and running fridges and, HELLO, charing about HALF the American car fleet with surplus night time power! Amory seems to think we need to beef up the grid to allow 50% extra electric cars to be charged during the day as well, but then assures us that their models show energy efficiency will mean they only have to build HALF of today's capacity!! Um, AND replace oil? Yeah, pull the other one it plays jingle bells!) Honestly, when I hear contradictions like this in wishy washy wishful thinking fairy land, I agree with Dr James Hansen! bravenewclimate.com/2011/08/05/hansen-energy-kool-aid/Meanwhile, if we assume we are going to build out 6 to 10 times the required capacity in wind, why build pumped-hydro that only stores power? Is it really that much cheaper than just building despatchable nukes? Indeed, we might not have to build as many multiples of wind capacity if we just build about half wind, half nukes. Or here's an idea: lets just build baseload nukes and run them day and night and not trouble ourselves with an unreliable, inflexible, 'wind when it wants to' and 'solar when it feels like it' grid! Renew Economy (Aussie renewables fans) are trumpeting about South Australia's recent sudden outage of a coal fired power station. Yellow = solar Green = wind Brown = coal plant which dies Red = gas which we must replace with despatch-able nuclear  |
|
|
|
Post by Scottish Scientist on Jan 17, 2017 22:35:44 GMT 9.5
Or we could build dispatch-able nuclear for truly CO2 free power generation in a real emergency. Here's a question for you, Scottish. Well my apologies for my late reply. I didn't receive a notification email about your reply. I had my notification option set to the default "smart" for "participated". I've set it to "instant" now. However, I would always encourage people to comment on my Scottish Scientist blog as the best bet to get my attention. What do you propose we do about replacing petrol and diesel? Well we need to phase out all fossil fuels. This can be done quickest by replacing fossil fuels with their renewable biofuel equivalents - bio-diesel for diesel, for example. Some bio-fuels, like bio-diesel, still cause a pollution problem, especially road transport in urban areas, so existing road vehicles should be converted to run on cleaner burning (renewable energy produced only if you please!) fuels such as bio-methane or dimethyl ether (which, like methane, is also very clean burning and easier to liquify under pressure than methane) or hydrogen (now that extraordinarily strong high-pressure tanks are available). Public transport should upgrade from diesel buses to hydrogen fuel-cell buses, with government grants to install the hydrogen refuelling infrastructure nationwide. Then citizens can be encouraged to prefer to buy hydrogen cars. Diesel trains can be electrified. If we're so busy backing up intermittent wind and solar just to run our power system, don't we have to build far more plants (like about 6 times as much capacity according to your Scottish graph) just to 'recharge' the hydro dams ready for the troughs? If only storing excess grid energy, yes. Whether it is 6 or 7 times as much capacity depends on how robust the system must be to cope with rare very low wind / solar periods. Fortunately, on-site wind / solar farm energy storage offers a solution that requires less generator overcapacity, by storing surplus energy that otherwise would have to be wasted by constraining or curtailing power generation because of insufficient demand or limited local grid transmission capacity. Where a wind or solar farm isn't conveniently located next to a hydroelectric scheme for pumped-storage then surplus wind/solar power-to-gas can be used to make hydrogen gas by electrolysis of water. I appreciate that supporters of nuclear power want to derail every thread to discuss nuclear power but I must decline your invitation so to do here. |
|
|
|
Post by eclipse on Jan 18, 2017 11:29:21 GMT 9.5
Yes, but the storage costs of all that plus overcapacity build... seriously, it's just fanboi words and wishful thinking! No costings, just so many words about what might be technically possible but economically impossible! "Can renewable energies provide all of society’s energy needs in the foreseeable future? It is conceivable in a few places, such as New Zealand and Norway. But suggesting that renewables will let us phase rapidly off fossil fuels in the United States, China, India, or the world as a whole is almost the equivalent of believing in the Easter Bunny and Tooth Fairy." bravenewclimate.com/2011/08/05/hansen-energy-kool-aid/ |
|
|
|
Post by Scottish Scientist on Jan 19, 2017 2:12:03 GMT 9.5
Yes, but the storage costs of all that plus overcapacity build... seriously, it's just fanboi words and wishful thinking! No costings, This is a topic about computer modelling a simple wind turbines / pumped-storage system. What matters there is the assumed relative costs of wind turbines versus pumped-storage because that determines the system designer choice, as guided by the modelling, of the optimal low cost mix of how much wind turbine power capacity and how much pumped-storage energy capacity. You've no right to complain when you lure me into a general discussion about renewable energy and demand that I provide all answers to all questions for your benefit. just so many words about what might be technically possible but economically impossible! "Can renewable energies provide all of society’s energy needs in the foreseeable future? It is conceivable in a few places, such as New Zealand and Norway. But suggesting that renewables will let us phase rapidly off fossil fuels in the United States, China, India, or the world as a whole is almost the equivalent of believing in the Easter Bunny and Tooth Fairy." bravenewclimate.com/2011/08/05/hansen-energy-kool-aid/What is most economically possible is the lowest cost renewable energy back-up to intermittent generation - namely biomass burning - not quite as clean as the gold-standard back-up methods of pumped-storage hydro and power to gas but biomass-burning certainly can be afforded. Please do not expect me to engage in a wide ranging discussion about renewable energy here in this topic about modelling. If you have nothing further to say about my modelling then I have nothing more to reply to you in this topic. |
|
|
|
Post by Scottish Scientist on Oct 24, 2017 23:37:08 GMT 9.5
I've extended my modelling to a include back-up generators and modelled some example working system configurations using scaled real world wind turbine generation data and demand data, from the UK grid during low wind conditions in September 2014.  Graph 8. Peak Demand (52,500 MW), Store – 0.6 days x peak demand (756 GWh), Wind – 2.7 x peak demand (141,700 MW), Back-up – 0.4 x peak demand ( 21,000 MW) I've summarised the results in a table. Table of wind, pumped-storage & back-up factorsThe factors in the table are peak demand power multipliers. Each row triplet describes a possible system configuration for 24/7/52 reliable 100% renewable energy generation.  Using these results, I have written a web-page script on-line calculator - Wind, storage and back-up system designer (my Scottish Scientist Wordpress blog post for documentation and discussion) Wind, storage and back-up system designer (the actual calculator web-page which has to be hosted separately because it uses javascript which Wordpress, the blog host, don't allow).  Peak demand, wind and back-up power / energy usage and storage capacity calculatorFor the specification and design of renewable energy electricity generation systems which successfully smooth intermittent wind generation to serve customer demand, 24 hours a day, 7 days a week and 52 weeks a year. Adopting the recommendation derived from scientific computer modelling that the energy storage capacity be about 5 hours [see note] times the wind power capacity, the tables offer rows of previously successful modelled system configurations - row A, a configuration with no back-up power and rows B to G offering alternative ratios of wind power to back-up power. Columns consist of adjustable power and energy values in proportion to fixed multiplier factors. The wind power generation Capacity Factor (C.F.) percentage can be adjusted too. Note: I should caution against unrealistic "green energy" expectations following news reports of commercial engineering companies peddling - "largest ever" batteries which can store only 10 or less minutes times the wind or solar power capacity. Such relatively small energy stores are grossly insufficient to design a power-on-demand system where energy is sourced in the main from wind and solar power generators.
At best, expensive energy storage from batteries can cobble together wind and solar generators as bit-part generators in a grid system where most of the power must still come from conventional dispatchable generators, usually fired by fossil fuels. Therefore "largest ever batteries" or other battery sales in this context are a commercial marketing deception and a fraud driven by the profit motive which trick and lock-in grid managers into continuing fossil fuel dependence. Such batteries offer no "100% renewable energy solution" at reasonable cost. The established technologies to expect to be deployed for wind and solar energy storage are pumped-storage hydro and power to gas. So Elon Musk is every bit the enemy of renewable energy as Donald Trump is. At least Donald Trump is honest about supporting coal.
|
|
|
|
Post by Scottish Scientist on Jun 24, 2019 5:57:17 GMT 9.5
|
|
|
|
Post by engineerpoet on Jun 24, 2019 9:22:31 GMT 9.5
Well we need to phase out all fossil fuels. This can be done quickest by replacing fossil fuels with their renewable biofuel equivalents - bio-diesel for diesel, for example. I doubt it. The land-use requirements for biodiesel in particular are prohibitive, and most biofuels aren't much better. The most feasible route appears to be to electrify everything, with the HEV/PHEV appearing to have the best match between capability and resource requirements for transport at the moment. Biofuels can fill in for what's left. As an example of resource requirements, the USA used almost 37 quads of petroleum last year. That's way in excess of any feasible biomass production, let alone specific high-quality inputs like vegetable oil. OTOH my calculations indicate that we might be able to produce ~20 quads of dimethyl ether, which can substitute for diesel fuel, LPG and also natural gas. If you've electrified 2/3 of your fossil energy demand, 20 quads is close to what's left over. Horses for courses. |
|
|
|
Post by Roger Clifton on Jun 24, 2019 12:59:56 GMT 9.5
Biofuels are fundamentally hostile to the environment in a world that is already too crowded. No land capable of forest should be considered so low in value that it can be diverted to producing low-density power. We already have concentrated power sources that consume negligible land, require no diesel fuel, and emit no greenhouse gas.
The diversion of land to support a vast area of solar panels or windmills is similarly frivolous. Pumped hydro is even more abusive of our natural assets, destroying selected wild valleys and mountainsides, cluttering the landscape with unnecessary power lines, pipelines and desalination plants that consume any productivity due to the panels etc and their storage. It is hypocritical for these believers to claim they are on side with Nature when they are so abusive of it.
|
|
|
|
Post by eclipse on Jun 24, 2019 17:39:26 GMT 9.5
|
|
|
|
Post by David B. Benson on Jun 24, 2019 17:54:49 GMT 9.5
eclipse --- I don't do Facebook. I don't do sites that require an app. My mobile device is quite limited.
Please post here more often.
|
|
|
|
Post by engineerpoet on Jun 25, 2019 0:50:26 GMT 9.5
Look at the energy cost of carbon extraction and reduction. F-T synthesis is a very lossy process as well. tl;dr Maximizing your useful energy per unit carbon is key to keeping the cost down. It looks to me like methanol gives you the max energy throughput, but it's rather toxic so it probably shouldn't be in widespread use. DME is relatively non-toxic and is one catalytic dehydration step away from MeOH. Lately? I'm watching the threads here pretty closely. They won't let me play in r/energy any more because I called scientifically illiterate nitwits, scientifically illiterate nitwits. Fine, let it be a cesspool. I prefer quality over quantity, which is why I came back here as soon as it came up on my radar. You might enjoy a couple subs I read: r/ColonizeMars and r/ColonizeVenus. |
|
|
|
Post by engineerpoet on Jun 25, 2019 1:00:34 GMT 9.5
As an example of how bad r/energy is, it has lots of totally clueless comments that would be material for r/Dumbass, if r/Dumbass was specialized in scientific stuff.
|
|
|
|
Post by eclipse on Jun 25, 2019 13:30:31 GMT 9.5
Ha ha ha, the irony. I just got banned from Energy for using tinyurls! Yeah, having a humanities background myself means I can't go too deep into the technicalities but I like to throw things out there in energy debates and see if certain *concepts* are even covered by certain 'studies' (like Mark Jacobson's 100% renewable 'studies'.) But that's why I value your posts and evaluation of certain subjects. For instance, that's why I'm surprised you prefer DME as the crowd over on BNC blog seemed to prefer the synthetic diesel solution I linked to for heavy vehicles. Does DME require a different kind of engine or massive refit of existing engines? Is this about laws of physics stuff impacting on the potential economics, kind of like the EV vs hydrogen debate where hydrogen has to do it's very round trip just to get back to electricity from a fuel cell again? Or is there something else going on? Sorry, I've tended to just plonk all synfuels into the 'needs high EROEI power source to start with' category in my story of weaning off oil, and of course being an ex-peak-oil-doomer, the hunt was on for that original power source. I basically just assumed the marketplace would sort out which synfuel. But I'm interested in your opinion.
|
|
|
|
Post by engineerpoet on Jun 25, 2019 21:43:30 GMT 9.5
DME retains more of the energy of the source syngas than F-T hydrocarbons do, and it has a higher cetane rating than most petroleum diesel. It's not compatible with current diesel injection pumps and injectors but the switchover appears no more involved than the switch to CNG/LNG would be.
I look at F-T fuels as a trap. First, synthesis is lossier so they cost more per unit of energy delivered. Second, they retain compatibility with petroleum so can always be slipped into the system without the consumer being the wiser; this has potential for massive fraud, and the cost difference creates incentive for it. Best to make a clean division between fossil fuels and their replacements.
|
|
|
|
Post by eclipse on Jun 28, 2019 13:27:03 GMT 9.5
DME seems expensive.
|
|
|
|
Post by Scottish Scientist on Jun 28, 2019 21:14:50 GMT 9.5
|
|
|
|
Post by engineerpoet on Jun 29, 2019 0:22:04 GMT 9.5
Everything is going to be expensive if you start from atmospheric CO2 and electrolytic hydrogen. There are better ways, though there are other resource limits on them. Speaking of resource limits or lack thereof, Highview Power's LAES (liquid air energy storage) scheme popped up at GCC. The claims of 65-70% efficiency are at least plausible. This is not as good as pumped hydro but the small footprint and lack of specific geographic requirements make it far more scalable. |
|
|
|
Post by eclipse on Jun 29, 2019 10:40:44 GMT 9.5
Hang on, I can't work this out. It's $140 per Megawatt hour if you buy a what? 10 hour * 200 Megawatts = 200 Megawatt hours, doesn't it? 200 MW is the unit of power, 10 hours is the unit of time, put them together and you just get 200 MWh?
So that means $140 / 320 homes = $0.43 per hour per home.
Interesting!
Now our average household price is something like the below, so in some states this price would be double the average hourly rate. However, with the continued economies of scale of solar power and wind, will they get cheap enough for enough of the day to cost spread the storage across technologies like this for the rest of the day?
South Australia $114.16/MWh
Victoria $100.12/MWh
New South Wales $88.06/MWh
Tasmania $82.73/MWh
Queensland $76.92/MWh
gobulk.com.au/australian-electricity-prices/
|
|
|
|
Post by engineerpoet on Jun 29, 2019 11:33:30 GMT 9.5
Hang on, I can't work this out. It's $140 per Megawatt hour if you buy a what? 10 hour * 200 Megawatts = 200 Megawatt hours, doesn't it? No. 10 h * 200 MW = 2000 MWh = 2 GWh. Normally I mock people who don't get simple physics stuff right, but you mentioned that you got sucked into the humanities so I'll ELY5. A 2 GWh system stores 2000 MWh of energy. Multiplying by $140/MWh, the cost would be $280,000. Compared to ~$100/kWh for Li-ion batteries, the LAES system is a bargain. (That number does seem awfully low given all the hardware in the video, and I wouldn't be surprised to learn it's a typo.) Of course, the LAES system isn't a monolith. Unlike a battery, its energy storage elements can be sized independently of its energy input/output elements (compressors and turbines). But a 10-hour size might represent the likely use case. |
|
|
|
Post by David B. Benson on Jun 29, 2019 13:26:51 GMT 9.5
Using a smaller liquid air storage system, Xie et al. Energy Procedia, v. 158, 2019 Feb, pp 4852--4860 obtain an LCOE in the US dollar range 250--375 per MWh delivered.
In my opinion this is expensive electricity.
|
|
|
|
Post by David B. Benson on Jun 29, 2019 16:47:20 GMT 9.5
Buy low, sell high:
In principle determining the LCOS, levelized cost of storage, is straightforward. I'll do a simple example of a pumped storage scheme which buys overnight and sells the following day at the time of highest wholesale market prices, maybe late afternoons.
The scheme is 75% efficient; for every 4 units of electricity provided, one is "wasted" and 3 are available for sale. If the purchase price is $12/MWh the sale price must be at least $16/MWh. But wait! There also the capital cost and interest to be paid, plus M&O, maintenance and operations, and also maybe a little profit. The M&O might be just $8/MWh but paying the finance charges I assume requires $56/MWh. So to break even, the LCOS, is 16+8+56=80 dollars per megawatt-hour. Selling for anything above that is profit.
This is much more complex to work out with more variable prices and timings.
|
|
|
|
Post by eclipse on Jun 30, 2019 8:48:14 GMT 9.5
Thanks EP! (Sorry, I was tired last night and didn't see the MwHOURS, I was just reading Mw. I thought I was converting from power capacity to Mwh. D'oh!)
I got the following conversion of capital price of an AP1000 into MWh from Mike Conley at the "Renewables vs Nuclear" facebook group. Coming in at $27.5 / MWh, my question is how 100% renewables advocates ever think storing wind and solar will ever break even with just using the money to build nukes in the first place?
|
|
|
|
Post by engineerpoet on Jun 30, 2019 9:25:23 GMT 9.5
<facepalm> He knows enough that he should know better than to make that mistake. |
|
|
|
Post by David B. Benson on Jun 30, 2019 9:57:15 GMT 9.5
eclipse --- Everwhere I know about, which leaves out the PRC, the maximum length of the construction loan, bonds, is 30 years. So the capital cost plus interest is paid then, considerably upping the LCOE for the first 30 years. After that there is only O&M plus so-called fuel so the LCOE is quite low.
A better estimate of the LCOE for a modern LWR is the BOO, Build-Own-Operate, contract between Rosatom and Turkish utilities for several VVER-1200 nuclear power plants currently being constructed: $123.50/MWh. On that Rosatom expects to double their investment in 30 years. By the way, this is a quite similar price to the guarantee for the new Hinckley Point reactor finally under construction in England.
|
|
