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Executive Roundtable: The Future of Utility-Scale Renewables

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14 Reader Comments
Comment
1 of 14
February 3, 2012
I've just scanned this article and can't find any mention of energy storage, utility scale or otherwise.

If we are going to adopt RE technologies at utility scale we are going to need something to compensate for their intermittency, which is either going to have to be conventional fast/medium response (and poor efficiency) backing generation or utility scale energy storage. Either that or, from evidence so far, we will need to install capacity very many times the base load, you can't time shift full utility load by days.

Don't get me wrong, I'm all in favour of RE and I believe it is viable, that's why I'm researching an energy storage/energy infrastructure that could deliver this scale of energy storage, which in the case of the UK would be in the multi TWh region, in fact according to Andy Boston (Technical Head, Business Modelling at e-on) his estimate for the UK is about 8TWh, about one week's worth of electricity generation!. This level of storage needs a whole new approach, working on it.
Comment
2 of 14
February 3, 2012
Nick's comment is on the money. Until we have a major breakthrough on storage, and a much more sophisticated grid, "storage" for utility-scale renewables will be gas fired turbines for off-hour (no sun, no wind) base load and peaking. In setting rates, the cost of constructing and operating the additional gas turbine plants will have to be considered part of the cost of renewables.
Comment
3 of 14
February 3, 2012
I have read on several occasions that off peak electrical production is either very cheap or is simply wasted. Also have read about compressed air storage of energy with heat storage for efficiency.
I don't understand why we can't store both H2 and O2 from hydrolysis to be used in fuel cells. I understand about losses in hydrolysis and compression of the gases. Also fuel cells can become fouled from contaminates. Pure H2 and pure O2 should not foul the fuel cells. Compressed gases can be stored for a long period of time and added to or taken away as a large buffer.
Initial costs may be high but should come down rapidly with more deployment.
H2 can be piped from where it is produced to where it is used as well.
Natural gas pipe lines and storage facilities are already well established and can be converted to H2 when we either run out of cheap natural gas or we decide that we must further reduce carbon emmisions.
I believe that H2 could also be mixed with natural gas and the H2 producer could get credit for the energy added. Often times wind energy production is near natural gas lines or at least electrical lines that travel to where natural gas lines exist. This way the energy value is mostly preserved and the H2 does not have to be compressed any more than the pressure of the natural gas lines. It could also be filtered out by the end user thru permeable membranes to be used at sight in fuel cells. Some fuel cells are already using H2 on sight by producing it from natural gas. This would simply make the natural gas supply even richer in H2.
This would use and preserve the natural gas distribution system and slowly convert some or all of it (slowly) to H2.
Interested in hearing more about how this would not work, OR how it could work for a cleaner energy future.
Regards to all, napaeric@sbcglobal.net
Comment
4 of 14
February 3, 2012
Gravity Power is developing bulk electricity storage which we feel will be true utility-grade, utility-scale energy storage for peaking power and to support RE penetration: www.gravitypower.net.

Venture-funded and soon to establish operations in high-growth energy storage markets (i.e. not the U.S.), the Gravity Power Module is based on the proven principles of the only widely deployed energy storage technology on the planet; we will provide the highly desired benefits of pumped storage hydropower, yet largely eliminate its challenges of the very lengthy siting and permitting processes and its requiring a huge amount of upfront capital to achieve its first Watt of additional storage capacity.

If all goes well, no longer will it be a decade+ and a few billion of USD upfront required to install additional clean, fast-responding, energy storage-based power plants of significant capacity and life.
Comment
5 of 14
February 5, 2012
Preston Peterson - Using hydrogen to store off peak electricity is not as simple as it seems, it is not that easy to store and transport due to its very low volumetric energy density, even in liquid form its only slightly better than ethanol. When you add losses from conversion (electrolysis), storage (compression) and fuel cell (about 60% max) the round trip efficiency is less than 40%. Even if this could be pushed to 50% it's probably not a brilliant solution and even at 50% it means you need about twice as much, difficult, storage as the required demand. Also hydrogen is probably not a good solution for long term (seasonal) storage.

C Grieco's post on Gravity Power makes a lot of sense for the lower end of utility scale storage but at the levels I mentioned in my first post, ~8TWh for the UK, even this is probably not the best solution as it would require over 13,000 of their 10m diameter by 2Km deep shafts, about 1 a day from now until 2050. I would agree with C Grieco that pumped hydro is 'currently' the only viable bulk storage solution and their version also achieves a much higher storage capacity (~2x)than a 10m by 20m hole with traditional pumped storage. The thing that makes pumped hydro storage cheap is its long service life and its daily cycling but multi TWh is for weekly or longer, such as seasonal, storage which completely changes the economics, for example; a facility that only gets used once a month would take 30 times longer to repay the capital than one used every day.

However nothing, except nuclear, compares to chemical energy as a storage method, particularly in a solid form. The solution I'm looking into would use 'green coal' (i.e. clean, recycled carbon) for storage and a hole, or better still a heap, of this volume would store in excess of 1.25TWh of electrical output, over 2000 times more than can be stored by Gravity Power. This is the scale and ease of energy storage that could really support large scale RE electricity.
Comment
6 of 14
February 10, 2012
Very interesting issues , we at Suneva currently jointly developing projects in puerto rico with NRG Caribe found a lots of similarities regarding RE issues.
Luigi
Comment
7 of 14
February 13, 2012
Really Very interesting issue. Thanks for sharing actually, this will be helpful for electricity suppliers comparison
Comment
8 of 14
February 14, 2012
Future for RE is in huge potential energy in deep waters of lakes and oceans. Utilization of deep water pressure is possible with single device capable of delivering GWatts of energy , device is under development, it needs push and investment and will be put for testing soon. This will enable to produce base energy and eliminate need for storage, excess energy will be compressed air to drive vehicles, using the pressure of compressed air with require only 10 gallon tank allowing to travel over 1000 km. REW should create conference to discuss this possibility, and help to promote this idea.
PV and kinetic energy devices are intermittent and 10 times less efficient than static pressure devices which cost 100 times less.
Comment
9 of 14
February 15, 2012
I wish people discussing RE, or energy in general, would learn the difference between ENERGY and POWER, Power is the size of the engine in your car, or to be more precise the rate at which the engine can convert the Energy (fuel) in the tank into useful energy i.e. mechanical work/motion in the case of cars.

Arov; "GWatts" (GW) is not energy it is power, energy is power times time, how long can you supply your GWs for? Energy would be GWh or GJ (GWs). Power does not do anything on its own, much like a battery has Volts but these don't do anything useful until it is connected to something.

The "huge potential energy in deep waters of lakes and oceans" is simply that, potential energy. To turn this into useful work, i.e. kinetic energy, the mass of water or compressed air, has to move to a state of lower potential energy, the difference being the available energy to do work. Sure you can store energy in compressed gas at the bottom of lakes etc. but you can't just extract useful energy from the pressure that exists unless the mass under pressure can move to somewhere of lower pressure.

"PV and kinetic energy devices are intermittent and 10 times less efficient than static pressure devices."
If the pressure is static it's not doing anything, that's why it is 'static' the efficiency of something that's not doing anything is not really meaningful. A hydro dam provides static pressure, potential energy, as a head of water but you don't get any useful energy out until the water flows through the turbines and unless you keep filling the dam, which requires energy, this will soon run out.

I don't have the space or time to do a rigorous explanation but there seems to be some flawed physics here.
Comment
10 of 14
February 15, 2012
Thanks for crushing respond.
Do not reject something that you do not know how it works.
Gwatts means actual energy output in 1 sec produced by my static pressure engine, new concept, testing presently going on using compressed air as pressure source (not propulsion technology) with loss of pressure only for leakage. It was time that people was killed telling that sun is not rotating around our planet.
Comment
11 of 14
February 15, 2012
To return to my comment regarding 'huge potential energy in deep waters of lakes and oceans' I have to admit I made a mistake.

What I should have realised is that the deep waters of lakes and oceans have water under 'huge pressure' not 'huge potential energy'. Pressure, however huge, is not in its self potential energy. Anything that's under a huge amount of mass will be under huge pressure, but this does not translate to huge potential energy unless this mass can move to a place of lower potential energy.

Arov. When you have finished testing your 'static pressure engine' what are you going to use in place of your compressed air source?

By the way, I've had a look at 'PIPS deep water static pressure to energy converter' @ www.world-wire.com/news/1010010002.html. It has two pistons that apear to move up and down under fluid pressure which is then translated into rotary motion. Moving pistons indicates moving fluid from one pressure to a lower pressure which is a perfectly normal way of harnessing the potential energy in a fluid under pressure to convert it into kinetic energy, but this does also imply a fluid flow, albeit a little different from the continuous flow through a turbine. On the basis that large turbines can harness close to 90% of the potential energy that was originally in the water stored in the dam I would doubt if there is a huge room for performance improvement.
Comment
12 of 14
February 15, 2012
Thanks Nick for taking time to look into my press release. This device is working with kinetic flow between cylinders for purpose of rpm limitation. Recently I invented new device that is considerably simpler and does not have internal flow, after compressed air test (which as goal has car engine with huge achievable travel distance and small tank) I will test device performance in deep water application creating pressure 5 bar 50m depth) using in lab. compressed air tank as pressure source.
Second part in case somebody will come out with support. Fact, that two types of devices (and sure will be more) can utilize pressure into energy, of cource with a twist, confirms as a fact, that nothing is absolute in engineering, absolute only that we did not look around enough, and that knowledge and human curiosity does not have limits, that's why we still have inventors. My invention came as a result of another SLT technology, which is my major invention in energy efficiency and really clue for static pressure utilization.
Sorry, in your first comments you talk about energy storage. If CAES use my last invention (air side) for release of energy stored, there will be more efficient and more effective CAES system
No image available
Comment
13 of 14
Anonymous
February 16, 2012
Regarding the idea that some sort of storage will bring down the cost of wind, I would not really agree. Any method of storage will add capital cost, and higher capital costs will only increase wind LCOE rather than reduce it.

There are many uses for electrical power. Industrial users tend to pay higher utility rates than residential users. So a more cost-effective approach might be to encourage industrial users of energy to relocate to areas with favorable wind conditions, where wind turbines can be installed and operated more profitably. It would seem to be more practical to use the power as soon as it is produced, rather than trying to store it. There is a long history of locating power-hungry industries near geographically remote sources of plentiful electrical power. That's why Alcoa aluminum and Boeing aircraft ended up in the Pacific northwest with its massive hydro power resources.

I would propose that installing low cost on-shore turbines in high-wind remote areas like Wyoming or South Dakota, and then building up a local industrial base around that source of power, is the most logical approach. The incentive of low cost power and low cost real estate will result in businesses voluntarily relocating. Having users move to the power source is cheaper and more efficient long term, than building out the infrastructure and transmitting the power long distances to existing users.
Comment
14 of 14
February 16, 2012
Its true storage will add capital cost but the problem with wind is it is very fickle and turbine output can vary from almost nothing to full output on a daily, possibly hourly, basis, even in Wyoming. It would not be possible to operate industry on such a flexible basis; employees would have to be swapping shifts on a daily basis. Also without storage you will need additional/over capacity to cover periods of low generation which may need to be several times the average output to give a reasonable certainty of having enough power during normal working periods.

If the wind is only supplementing the normal grid power then the problems may not be significant but in this case it still means that the grid will need to be taken to where the wind source is for backup.

Storage and interconnection are the answers, but the storage has to substantial, cheap and able to provide at least a few days of supply if wind is to be the predominant energy source. In the UK in Dec 2010 wind output for the whole of the UK dropped to about 5%, or less, for over a day on three separate occasions, two of which were for about 3 days. Wind currently only supplies a very small fraction of UK energy so conventional generation is able to make up the difference, but if wind provided a major part we would have been in a bit of a pickle.
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ISSUE COVER IMAGE: About Renewable Energy World (North America Edition)
 

Lindsay Morris

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About: I am an associate editor for Power Engineering magazine. I cover EPA's regulations for the power industry in detail. When it comes to renewables, I write regula... more »

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