Energy Storage Benefits Renewables–and All Other Resources
A reader notes: “Fossil fuels (and nuclear fuels) provide energy storage. To replace them with renewable energy sources like wind we’ll need to incorporate a means of storing the energy.”
This isn’t completely incorrect, but it’s misleading, and it provides me an opportunity to clarify, in a summary fashion, the whole issue of energy generation, storage and consumption.
• It’s true that energy sources like coal and nuclear fuels store energy (coal with its strong chemical bonds and nuclear with its large and unstable nuclei). And yes, both can be converted to heat or electricity when we want, but we don’t have absolute freedom here; the process of doing this is very hard to regulate on an hour-to-hour or minute-to-minute basis. Once one of these plants is started, it runs at a more-or-less constant level of power production for months at a time, thus the name “baseload.” Conversely, the load we humans demand ramps up and down fairly dramatically during the course of a 24-hour period, and thus can’t be mirrored precisely with these fuels. For that reason, even coal and nuclear benefit from energy storage, e.g., pumped hydro, saving off-peak energy for times that it is needed, long after it was generated.
• It is also true that variable resources like wind and solar do not mirror the ever-fluctuating load that we demand. This means that one of four things must happen:
a) We need to consume it on the spot. This is what happens with almost all renewable energy. Take solar energy, e.g., whether it’s on your rooftop or out in a solar field, where the power is purchased and distributed though the utility grid. A photon from the sun hits a PV panel, and a tiny fraction of a second later, the resultant energy is pushing through the distribution lines, powering our toasters, hair-driers, etc.
b) We store it, in a way not unlike what I described above. It can be used to make water flow uphill (pumped hydro), charge a battery (which could be in an electric vehicle), or flow into some other storage technology.
c) It’s exported somewhere else. Examples here are things like “net metering,” where the solar energy we don’t need at the moment is sold back to the grid, and used to toast someone else’s bread, charge someone else’s EV, etc. There is a limit here, of course. Our current grid doesn’t allow us to generate a huge amount of energy in one region, say, the plains states (where it’s windiest), and send it immediately to the large population centers on the U.S. coasts. Over time, however, this is changing for the better as we improve our grid.
d) It’s lost. If you can’t use, store, or transmit the energy you’ve generated, it’s wasted. An example of this is so-called “curtailment,” where wind turbines are turned off for periods at night where demand is low and supply is high.
• In their current quantities, for right now and at least the near future, the effective use of variable resources like solar and wind requires no storage at all. Wind presented 4.18% of the grid-mix in 2013, and solar was 0.23%. Until wind at least triples in volume and solar grows by some enormous amount, both of which will require many years, storage will add very little value in terms of successfully integrating renewables. We should note that, during this time, the R&D associated with storage is progressing nicely.
I hope that puts this subject into better perspective.
The time for energy storage project development has arrived. Costs for energy storage, especially with Compressed Air Energy Storage, are low. When combined with nighttime wind power, CAES produces a baseload power at prices that beat the price of fossil fuel sources. Environmental and climate change costs of fossil fuels are no longer affordable.
Craig,
There is another option that is considerably cheaper than energy storage. (Virtually anything is cheaper than energy storage in most situations.)
Energy consumers can vary their consumption according to the availability of cheap power. This makes considerable sense for industrial processes that are energy-intensive with some opportunities to build up buffers along the process chain.
http://www.leonardo-energy.org/sites/leonardo-energy/files/documents-and-links/cu0202_an_wind_powered_industrial_processes_v1.pdf
You’re absolutely right; I should have mentioned that.
How are things in Norwich, that picture postcard of a town?
https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1920&bih=936&q=norwich+england&oq=norwish+eng&gs_l=img.3.0.0i10i24.1322.4555.0.6024.11.11.0.0.0.0.117.1000.10j1.11.0.msedr…0…1ac.1.60.img..0.11.986.1rwdGxKpwVs
Cold Craig.
Something you probably don’t experience in California.
Aedan
That’s for sure. We do have beauty here, but a) we don’t have your lush greens, and b) we have very little history; there were no buildings here before the mid-19th Century; most of this place was built in the last few decades.
The time for energy storage is now as mentioned in the first post, because the price of energy storage keeps dropping, thus the potential for the a massive deployment of this technology increases. There are two interesting items that we could consider according with Navigant Research within the next decade you can expect 21.8 GW of energy storage worldwide, in addition you can see the in Europe and in particular Germany there is a strong movement to place energy storage in homes this year alone 20% of all systems installed in the range between 3-9KW have energy storage.
$500/KWh is the average price for a system today, although the vector points towards the $350/KWh for 2017 then you can anticipate a spike in the number of installations, in addition companies such Ambri a MIT spin off is aiming to use its liquid metal batteries that can potentially produce energy for less than $50/KWh when they are able to ramp up their production.
So the future of energy storage is bright, we hope that all the players involved are able to put their act together and benefit of this great technology.
Why did the coal power utilities brainwash us to believe that wind and solar energy are the only viable alternatives to coal power? Answer; because both wind and solar are intermittent energy sources and require the coal fired power stations to be kept online and ready to back them up and because biomass and trash-to-energy could enable us to shut down those coal fired power generations.
Actually, some coal burning plants can vary their output to a considerable degree, but at the expense of efficiency. Even if load following did not reduce efficiency, running at less than full power reduces the return on the investment.
France has nuclear reactors designed for load following. If ordinary pressurized water reactors are used for load following, the fuel is not used evenly which runs up costs. France has reactors with the control rods arranged differently and controlled differently to minimize, but not completely eliminate, that effect.
However, it should be clear that regardless of what type of power source we use, return on investment is maximized if it is always run at full power which, of course, is not possible for all generating stations since at least a few of them must be able to do load following unless power storage is available.
Although adding storage would improve the efficiency and return on investment for ALL power sources, one must also consider the cost of the storage and its return on investment. The cost of storage depends on the type of storage available. Although costs of energy storage have been dropping, they will always remain significant. If energy storage were cheap enough, it would make sense to use it even with coal and nuclear power. Perhaps that could happen, but attempts to predict the future are very risky and we should not count too heavily on things which do not yet exist.
Even with unlimited and free energy storage, if all power were provided by intermittent sources, their peak generating capacity would have to be far greater than if they were not intermittent. For example, let us assume that a wind farm, on average, could generate 1/3 of its peak power. That means that a three gigawatt peak power wind farm would, with unlimited storage, provide the same power as would a one gigawatt power system that could be run continuously at full power. A similar situation exists with solar power. Because intermittent systems must be greatly over-built and have storage, it is very difficult for them to compete with systems that provide continuous power. It is very difficult to compare them using published data.
In some areas, the cost of power depends on when it is used. When used off-peak, power companies charge less which makes good economic sense because it motivates customers to shift their peak usage to times when the power costs less. Also, some loads, such as air conditioning, can be dropped for short intervals to reduce peak loads. For that reason, some power companies have the ability to power down customers’ air conditioning when high demand for power threatens to overload the system.
Some very large air conditioning systems generate ice during off-peak times and use the ice for cooling during peak times. Although that does reduce the efficiency of the air conditioning systems and requires a greater investment cost, shifting the power load to off-peak times does make economic sense.
It should be understood that eliminating the usage of fossil fuels would increase the demand for electricity as there is a shift to using electricity for cooking, heating, and transportation. Thus, using the wind and sun to generate an adequate amount of electricity as demand for it increases is more challenging than many people realize.
Joe and Rogelio are on the right track.
Unfortunately though, what we are not discussing much these days is the important counter argument that the world actually needs to start focusing on consuming a lot more energy across the board [in the order of several magnitudes] to enable the new era human services development and sustainability industries, to come on steam everywhere. Those industries will be very dependent on energy intensive technologies processes and procedures particularly in the artificial agricultural and food science industries, and new tech infrastructure development technologies.
Any talk of energy frugality being embraced as the norm is short-sighted and not visionary at all. The engineering science required to make this possible looking forward is in the hands of the world’s best and brightest young physicists and scientists, and there is no doubt they will achieve the necessary thermodynamic science breakthroughs that will consign this low footprint thinking about global energy frugality to the waste bin forever. The world requires “low cost and abundant power” whenever and wherever required.
There is a pathway though to get to that point. I understand that, and I am involved in the renewable energy industry like yourselves heading merrily along that pathway. But those genuine renewable energy practitioners on that pathway need to all understand that their particular interest “at the moment” is simply a point of time along an inexorable process pathway. Do your best with what you have got around you in technology at the time for sure, but be enthusiastically mindful of where we need to and have to get to in the longer term. Don’t be tempted to stomp on expansive notions.
Talking storage for example, I have in the last few months been working with a commissioning team on a 48 MW [in 3 stages] traditional solar PV plant at an industrial township in Shandong Province China which incorporates complimentary sized compressed air storage. Joe would be impressed, me to, but I like to remind myself that in the overall scheme of things, really it is a transitionary step only. It was an expensive project overall and that’s not what we need. I emphasise “low cost and abundant”. But nevertheless it reflects an important step along the pathway in my mind.
Like all electrical generation supply networks [viewed as an equivalent simple circuit] the demand varies and the supply source responds; storage behaves the same way. It is also possible to have a near balanced supply and demand “conspiracy” achieved between prime source and secondary source through accurate sizing. What is not good design though is a deficiency in available power at any one time that needs to be compensated for by a third source to maintain a critical supply system. A small surplus is good maths though.
Engineers need to re- focus on low cost and abundant [at all scales and for all situations] energy technologies. But expensive is not tolerable. The emphasis is on low cost and abundant. That is the engineering challenge ahead, and there are groups of design engineers everywhere focused on these points.
Lawrence Coomber
Fossil fuels and nuclear store energy in different form not as electrical energy.What we need is either either electrical energy or instantly available like UPS or flywheel or battery or capacitor.
Naban discounting fossil fuels, there are only a few realistic methods available that provide for secondary “energy storage” opportunities.
They do share three important attributes in common though. [1] they exist in a format that can be tapped into when required; [2] they are able to be replenished via a “storage mechanism or process that also consumes energy in doing so”; and [3] they are able to be transformed into useful electrical energy as required.
For your information, batteries are a chemical potential energy storage technology, able to be transformed into electrical energy when required.
So let me list these few secondary storage options: [1] Chemical potential energy [batteries, capacitors etc.]; [2] Kinetic potential energy [circulating water; pumped head; flywheel, for example]; [3] Thermal potential energy [solar heat capture for creating superheated steam for driving turbines normally].
We all know these technologies well by now and no one disputes that. The real issue though for our researchers and engineers to grapple with is that just because these technologies and methods are all known and work well, that doesn’t mean that they include a built in guarantee to be useful and cost effective, and most importantly just because they exist, is someone prepared to pay for them.
In fact we are seeing this very subject explode all around the world at the moment with wind power; in a nutshell is it affordable; is that affordability sustainable, and importantly hands up those willing to pay and continue to pay.
So your discussion is really sheeted back to economics Naban, not the known engineering options that you have pointed out.
Listing energy technologies is very easy to do – explaining their affordability and validating their future usefulness through objective financial analysis is another question indeed, and it’s this point that we need to focus more on as we move forward as design engineers and researchers.
Like yourself I have my own view on what is best regarding secondary energy storage thinking, just as many others do also, and that involvement by many is what drives the experts onward and upward.
There will be many “technology causalities” on the path forward and that is a good thing; we need to consign many cost inefficient technologies to the waste bin without fear or favour as we go forward, even though they work well.
Well done Naban I enjoyed you posting.
Lawrence Coomber
I like electrical/kinetic storage not thermal which can fail to start sometimes,even trip.
Craig:
An exergy store inherently stores both heat and electricity (in the form of exergy) and in the process it also accumulates both energy and exergy from local sources (up to 657 PJ/y in Ontario, for example). The charging timing, rate and storage quantity are controlled by the grid operator while the recovery timing, rate and quantity are controlled by the building operators.
In most Canadian provinces exergy storage systems could eliminate the need for fossil fuels for heating, cooling and DHW and they can save a lot of money (up to $44 billion per year in Ontario, for example) by making the power grids more efficient. They do not need fuel, they greatly reduce the maximum power capacity that is needed, they handle both supply and demand fluctuations, boost generator efficiencies, reduce the need for the grid to transport energy, etc.
Exergy stores cannot be analyzed like battery stores because they are concurrently doing multiple tasks. The Sustainability paper provides a more comprehensive description.
http://www.mdpi.com/2071-1050/6/11/8297/pdf
They work best in places that have wide seasonal temperature variations.
Mr. Eggers wrote; Although adding storage would improve the efficiency and return on investment for ALL power sources, one must also consider the cost of the storage and its return on investment. The cost of storage depends on the type of storage available. Although costs of energy storage have been dropping, they will always remain significant” to which I would like to ask readers to consider how much it costs to store municipal trash on the tipping floor until peak demand times, which normally occur about twice per day I hear. And compare that cost to the cost saving of not hauling that resource far away from the population center to the landfill and paying to tip it off there.
Very well stated Craig. Renewables have a long way to go before we need to overly worry about the fact that they are intermittant. That said, it has ignited the current interest in storage which in turn has lead to meany new applications andthe price dropping. Almost overnight, we are all looking at where we “waste” energy by either not producing when we could cheaply (e.g. curtailment), or are ineffecient on demand vs. load. That is the main reason storage is growing now – not because of renewables!
I see this as a virtuous cycle. What you said that most people need to keep in mind is that we are on a journey and in the very early stages. It is normal for people to resist change, but as the economics improve, others adopt.
Remember early cell phones? We were told that they were never going to compete with landlines for cost or efficency. The energy transition will take longer, but fundamentally, wind power and sun energy are there for the taking. The Utility model we have had for the last 50-100 years is just a model – and models change when new factors come to play.
Thanks again for your article. It was very well put.
The need for storage is “here and now” in many places. The source value for electricity cycles through a large range on a daily basis. In Ontario, for example, that value falls very nearly to zero at night, 365 days per year, and in some seasons the power producers have to pay nearby consumers to take the power away. That makes wind power particularly unattractive.
Moreover, renewable energy sources that lack storage are inefficient and that is a deterrent that applies right now. For example, run-of-the-river hydro stations are typically about 2.7 times less efficient than high dams that are able to store a river’s energy during high flow periods. If you added energy storage to the system then existing hydro stations could deliver up to 2.7 times as much electricity without making any apparent change in the dam or in the river flow (but you would need to add turbines).
In the case of exergy storage systems, which can store both energy and exergy in very large amounts, the extra electricity can be used to collect and store heat extracted from the summer air and from solar thermal collectors. That can more than triple the amount of useful energy, utilizing energy sources that are presently being ignored. Although the energy is in the form of heat, not electricity, in regions where there is a high heating or cooling demand the exergy storage has the same impact on the power grid as the same amount of electricity storage. See http://sustainability-journal.ca for details.