CAISO Report - Integration of Renewable Resources

CAISO - the California Independent System Operator - is constantly worrying about the impact of renewable wind and solar generation on the California grid. It's their job as the grid operator - gotta keep the grid stable and the lights on. The problem with intermittent - oops, sorry, variable generation - "variable" is the new PC term for intermittent - it just sounds so much better - the problem with variable generation is that it is "variable". The grid can't dispatch it when it is needed, like a natural gas peaker plant. It just happens when it wants to happen, whether it is convenient or useful or not.

As a result, CAISO is always studying the problem, and the latest report just came out. Here are some of the highlights:

• First, you'll be happy to know, is that the California grid can handle 20% penetration of renewable resources. Of course, there are some caveats. For example, the increased production of solar and wind energy will displace traditional thermal generators, so their revenue will decrease. In other words, we are likely to put the current generators out of business. Hope you are not invested in one!
• At the same time, we are going to need to keep those plants that are now uneconomic, because we need them to balance out the rapidly changing wind / solar PV generation.

"The integration of variable energy resources will require increased operational flexibility—notably capability to provide load-following and regulation in wider operating ranges and at ramp rates that are faster and of longer sustained duration than are currently experienced. Forecast uncertainty associated with wind and solar production will increase the need for reservation of resource capacity to ensure that these requirements are met in real-time operations...In providing these capabilities, the existing and planned generation fleet will likely need to operate longer at lower minimum operating levels and provide more frequent starts, stops and cycling over the operating day."

Exec. Sumary, pg. iii.

Again, the existing fleet of generators is going to loose money, "The lower capacity factors combined with the reduced energy prices under 20 percent RPS may result in a significant drop in energy market revenues for the gas fleet in all hours of the day and in all seasons." - pg xiv, but we need the entire fleet to keep renewables from crashing the grid, "The additional regulation requirements appear to be well within the capabilities of the existing generation fleet."

So, as long as we keep the current, money - loosing generators, and work them harder, for less money, we can add variable wind and solar without black-outs. Of course, ramping them up and down so much will increase their cost - for less revenue - and increase their emissions - adding pollution when the renewables are supposed to be reducing emissions.

The trade-off on emissions is supposed to come from lower over-all energy generation. Since they will produce less energy, the increased emissions from inefficient ramping will still be less than if they were at full production, although the impact from this type of operation was not calculated."The table also shows a reduction in CO2 emissions from combined cycle generators due to the reduction in operations, although this was calculated using a single emissions factor multiplied by energy output, and did not consider the potential for higher emissions at less efficient levels of operations." pg.86.

And the report made certain assumptions about the status of this generation fleet, that it will increase in capacity, not decrease:

• "Table 2.10 shows the new and planned thermal resources that were included in the analysis. These resources were included as they are currently under construction and have little or no risk of not being available in the 2012 timeframe. No resource retirements were modeled, nor were sensitivities conducted for the status of once-through cooling (OTC) plants. OTC plants are slated to be retrofitted or shut down after 2013 and are not expected to affect the 20 percent RPS integration. However, they could affect renewable integration after 2013, and hence are being examined in the ISO’s 33 percent RPS operational study."

So, the bottom-line seems to be that we should be okay until 2012, because we can thrash our current peaker plants up and down and avoid grid collapse. But all bets are off for any increase over that.

We think increased penetration of energy storage is a better balancing strategy then building more natural gas peaker plants. Using energy storage, like the VRB-ESS™, allows variable resources to be fully integrated without increasing emissions. As we plan for 2020, we hope the regulatory agencies will continue to look toward clean technology resources to integrate renewables, and keep clean energy "clean".

Efficiency of Pumped Hydro Contest - Dud!

My contest to try and get some real figures on the round-trip efficiency of pumped hydro was a dud! No studies, no real world numbers. I heard from a few helpful readers that had projected efficiency numbers based on new turbines from Japan, but no information on existing projects. I find this highly interesting because new advanced energy storage systems, like the VRB-ESS(tm), are being compared, sometimes unfavorably, against pumped hydro. If PH is the gold standard for highly efficient time-shifting power generation, then one would think there would be substantial and easily accessed information on real-world experience.

I may try this again. In the meantime, if any reader has any resources on the subject, please leave a comment.

While we're on the subject, here are a couple of interesting points on the electricity in - electricity out efficiency of the VRB. The standard metric is 65% - 75%, AC-AC. However, the actual round-trip efficiency depends on the application.

For example, the lithium battery providers, like A123 and Altairnano, and flywheel providers, like Beacon Power, are advertising 90% efficiency. However, this is for a very limited pulse of power in the middle of their state of charge (SOS). The application is used for balancing the 60Hz frequency of the grid by pulsing to full capacity - in megawatt size - for only 15 minutes. Apparently, just about any battery system, including lead acid, could pulse like this, in the middle of their SOC, with high efficiency and many cycles.

This applies to the VRB-ESS as well. The greatest efficiency loss occurs at the end of the charge cycle, as it takes more work to find "uncharged" vanadium ions to "fill up the tank". In other words, if a facility had installed enough tanks of electrolyte to store 8 hours of energy, but only used the first 6 hours, then the round-trip efficiency would be closer to 80% than 70%, and if the VRB-ESS was used for the same application as the lithium systems, the efficiency would be the same - in the 90% range. However, one of the key distinctives of the VRB is the ability to fully cycle a nearly unlimited number of times without loss of capacity. Capacity is dependent on the amount of electrolyte. So, an application could chose 30 minutes of storage or 8 hours; it's simply a function of how much electrolyte is stored in the tank. After thousands of full cycles, whether on a 30 minute tank of electrolyte, or an 8 hour tank, the VRB is still able to provide full capacity and for the same amount of energy.

Contest! Prizes! Discover Efficiency of Pumped Hydro!

Please help us ferret out (apologies to mink and weasel lovers!) information on what appears to be a great mystery - the round trip efficiency of Pumped Hydro Energy Storage. Prizes will be awarded!

The round trip efficiency of storage technologies are of great interest and discussion. Some are concerned about "wasting energy" when storing electricity. "Losing" 30% of the electricity going into a storage facility is a "non-starter" for them. However, others counter by pointing out the greater value of electricity delivered on-peak, even if some energy is lost by storing off-peak power.

The number one storage technology in use today is pumped hydro. These are, usually, massive projects, where water is pumped up to a reservoir at night, when power is cheaper, and allowed to flow downhill during the day. The turbine used to pump the water uphill is then spun backwards by the water coming downhill, generating electricity. Whenever energy storage is discussed, pumped hydro is held up as the ideal answer due to it's large storage capacity, low emissions (although some have begun to be concerned about the amount of methane released from underwater biomass), fast response (although only when generating electricity) and high efficiency. However, your humble blogger has had a difficult time finding authoritative literature on pumped hydro efficiency, and I'm hoping to tap the resources of other, more knowledable members of the industry, by tempting them with fame and fortune.

As an example of what appears to be unsupported but accepted wisdom, NREL recently published their technical report on energy storage, and said this about pumped hydro:

"PHS plants can achieve round-trip efficiencies that exceed 75% and may have capacities that exceed 20 hours of discharge capacity. (pg 43)" However, even though this is supposed to be a technical report, no citation was offered.

Again, the Electricty Storage Association indicates efficiencies in the 70 - 85% range, but no authorities or links are provided.

I would tend to accept these statements as accurate, not knowing any better, but I have been at conferences where such claims have been hooted at by participants, with counter claims of less than 65%. This has piqued my interest in getting some authoritative answers, especially since the VRB-ESS achieves efficiencies in the 70 - 75% range when used for the same purposes as PHS. Obviously, if efficiencies of 70% or less are not a problem when applied to PHS, then higher efficiencies from a flow battery, like the VRB-ESS, would be even more desireable. If, however, PHS is much less than 70%, then alternative storage systems become even more attractive. But we need to know the facts before we can have an informed discussion.

Hence my contest. We will award prizes and fame to those that provide the most useful resources discussing PHS efficiency. Unless you wish to remain anonymous, we will announce the three commentators that provide the best citations or other authoritative resources. And, the winners will receive their choice of the Enerdynamics publications, "Understanding Today's Electricity Business" or "Understanding Today's Natural Gas Business". Both publications are valued over $60!

As a bonus, anyone that also provides authoritative analysis resources on the actual per kWhr cost of PHS will receive both books = $120!

I'm having a little bit of fun with this, but it looks like a good project given the dearth of information, or so it seems to me, on pumped hydro storage efficiency. Your comments will be posted below, therefore contributing to the general store of knowledge, unless you prefer to email your offerings to ctoca@utility-savings.com. I will be the sole judge of the winners - since it's my contest - and we will close the contest on Thursday, April 15th, so we won't continue to "tax" your patience!

Please click the "Post a Comment" link below or email your replies. Thanks for the help!

CAISO Postpones Entry of Energy Storage

The California Independent System Operator (CAISO), the state agency running the transmission system, has postponed the entry of limited energy storage resources (LESRs) into their ancillary services markets.

CAISO is bound by the Federal Energy Regulatory Commission (FERC) Order Nos. 719 and 890 to allow Non-Generator Resources to participate "on a comparable basis to services provided by generation resources in meeting mandatory reliability standards, providing ancillary services and planning the expansion fo the transmission grid".

To that end, CAISO began a stakeholder proceeding in September, 2009. LESR technology providers, like the Beacon flywheel, Altarinano and A123 lithium ion batteries, saw this as an opportunity to open these markets to their short term energy storage systems, as they have been able in other ISO markets. Many saw this as a continuation of the various energy storage proceedings that have started and stopped without resolution at CAISO since 2008.

However, the existing CAISO markets require greater energy resources than the above technologies can provide. Although CAISO reduced their requirements from up to 2 hours of energy, to as little as 30 minutes in the course of this proceeding, the LESR technologies are limited to 15 minutes of energy in one direction - charging or discharging. In fact, they want to be paid for providing service in both directions, requiring them to operate in the middle of their capacity, which only allows them to provide 7 minutes of energy - more or less.

The final decision of CAISO, after months of meetings and stakeholder comments, was the determination that new ancillary services markets would need to be created for these technologies because, "...energy storage and other resource have different operating characteristics and different implementation issues." (Draft Final Proposal, page 3)

CAISO proposes to take up the issue of LESR participation in future proceedings, although the timing is uncertain. This is understandably disappointing for the LESR companies, who have seen some success in other ISO territories, either with full participation or through pilot programs. However, for the foreseeable future, limited energy storage will not be able to participate in CAISO markets.

However, nothing in this decision or other proceedings prevents other energy storage technologies, with longer energy capability, from participating in CAISO markets. For example, the VRB flow battery, with the ability to store hours of energy, qulifies to provide spinning reserve, frequency regulation and other ancillary services. The VRB Energy Storage System (VRB-ESS), sited in conjuction with a solar PV, could shift generation, maintain peak output for the solar generator, and could then provide services to CAISO when not needed for solar energy.

I know this blog is about the VRB Energy Storage System, but...

I guess I'm one of those people who will step aside when the herd is all heading one way to look and make sure we're going the right way, and not off the cliff. Never been a lemming. I don't readily accept the "conventional wisdom". I've found out that usually, when some concept attains universal acceptance, it is probably due to some other reason than good logic, facts or common sense. So, I like to find the "other side of the story" - there is always one.

The VRB ESS fits in this concept. Popular sentiment is rushing toward renewable energy, like wind and solar, without truly considering the consequences. I believe we should develop distributed energy resources for many good reasons, including homeland security, energy independence, and local control v. centralized control. The VRB-ESS connected to solar PV or a wind turbine will provide all of that. And we'll need large energy storage facilities like the VRB to make large wind and solar PV installations useful and to prevent them from crashing the grid due to thier intermittant power output.

But I'm far from convinced that we need renewables to save our planet from global warming (opps! I mean climate change...) There, I've said it. But, even though I don't follow the climate change faith, I still have common ground for the reasons stated above.

All this so I could share these interesting bits:

No rise of atmospheric carbon dioxide fraction in past 160 years, new research finds

ScienceDaily (2009-12-31) -- Most of the carbon dioxide emitted by human activity does not remain in the atmosphere, but is instead absorbed by the oceans and terrestrial ecosystems. However, some studies have suggested that the ability of oceans and plants to absorb carbon dioxide recently may have begun to decline and that the airborne fraction of anthropogenic carbon dioxide emissions is therefore beginning to increase. In contradiction to those studies, new research finds that the airborne fraction of carbon dioxide has not increased either during the past 150 years or during the most recent five decades.

And also:

Can Carbon Dioxide Be A Good Thing? -- Physicist Explains Benefits Of Carbon Dioxide

ScienceDaily () -- A physicist from Colorado State University and his colleagues from the North American Carbon Program (NACP) have discerned and confirmed the unforeseen advantages of rising carbon dioxide levels. Through the processes of photosynthesis and respiration, scientists have been able to elucidate why plants are growing more rapidly than they are dying. The NACP is employing methods, such as the use of cell phone and aircraft towers to monitor and retrieve carbon data for their continuing study.

CAES - Lies and Damned Lies

With apologies to Mark Twain, I keep thinking of his categorization of whoppers when I hear the misleading, if not willfully false, claims made for Compressed Air Energy Storage - CAES.

The Wall Street Journal has a story on the DOE grants for CAES, due to be announced soon. $60 million is planned to "promote a patented technology that stores energy until it is needed".

First, referring to CAES as "energy storage", is a stretch, if not downright misleading. The WSJ doesn't mention that the compressed air is "stored" for the purpose of firing a natural gas generator! Yes, that's true - a natural gas, greenhouse gas emitting, fossil fueled generator.

Advocates of CAES are quick to point out that using compressed air increases the efficiency of natural gas generators, from about 33% to as much as 88%, so less GHG is emitted. That's great for fossil fueled generation, but don't call it energy storage. However, as discussed in an earlier blog, on an energy in - energy out basis, counting the energy used to compress the air, actual energy efficiency is about 54% or less. But I digress...

Second, how can anyone compare CAES to advanced batteries - like the VRB-ESS - and conclude that it's, "much cheaper than battery storage and far more durable"? The article quotes Robert Schainker of EPRI advising that batteries are too expensive. Elsewhere he is quoted as saying CAES costs about $700 per kWhr. If the PG&E project stays on budget - how likely is that? - then PG&E will get 10 hours at 300 MW, or 3,000 MWHrs for under $400 million, about $133 per kWhr? Wow, what a deal - if it happens. However, what about the cost of the natural gas? No information has been provided yet, but 8 million MMBtu per year seems in the ballpark. At $7 MMbtu, that's at least $560 million over 10 years. Twice that over 20 years. And what are the O&M costs? The generators are typically completely overhauled every 10,000 hours. We need more information...

By contrast, Prudent Energy is expecting the VRB-ESS to run about $500 per kWhr for 6 hours of storage within 2 years, and much cheaper for a 10 hour system. Refurbishment at 10 years, for about $60 kWhr for a 10 hour system, will allow the ESS to run another 10 years. And, wind power can be stored and delivered as needed, without emissions, with about 75% efficiency.

One final digression - if renewable energy, subsidized by taxpayers, is used to enhance a natural gas generator, is it still "renewable". Renewable wind power is consumed to run the air compressors. The compressed air is then released to enhance natural gas generation, turning "clean" energy into "dirty" energy. What does this do to the Renewable Portfolio Standards? Does wind energy, that is not delivered to consumers, but instead is consumed to produce natural gas fired electricity, count toward the 20% - 33% RPS?

There's no guarantee a 300 MW CAES will or can get built as expected, or that it will ultimately cost under $400 million. However, VRB systems can begin to be installed at wind farms and end-users now. It's more likely that 300 MW of VRB batteries can get installed in 5 years than CAES, and we won't have to substitute wind power for natural gas.

How Do You Value Grid Connected Energy Storage?

This is almost a part II to my earlier post, but I was reminded again of the problems we face when it comes to defining, and then valuing, Grid Connected Energy Storage (GCES).

The recent New York Times article, "Companies Race to Develop Utility-Scale Power Storage" pointed up the problems and potential for confusion. "Power storage" technologies listed included the Beacon flywheel, the NGK molton sodium-sulfur battery, the A123 lithim ion battery, and compressed air (again!). Quoting a report by GTM Research, this article made a very insightful distinction between "power oriented" technologies, used mainly to regulate short-term changes to grid frequency, and "energy oriented" storage -- in which energy use is shifted to other times of the day. However, the author could have done a better job applying this distinction and pointing out the difference in cost.

For example, the article discussed the $69 million Beacon project in New York, where they will install, "...hundreds of "flywheels" to store 20 megawatts of electricity, enough to power 200 homes for a day." In reality, the flywheel is designed to store only 15 minutes of power and falls into the "power oriented" category above. Its total energy storage will only be 5 MW hrs, about enough to power 40 homes for a day, although it will never be used for that purpose.

Also, the article reported on the $25 million requested by Southern California Edison for an A123 "32-megawatt-hour battery" - but is it really 32 MW hrs? I pose the question because the system will be designed as an 8 MW battery with 4 hours of storage (32 MW hr), but the application is at a wind farm, where multiple cycling is needed to firm wind - a "power oriented" application. Lithium ion batteries are good for about 500 - 600 complete charge and discharge cycles. If it is used in an "energy oriented" application, shifting wind power at night to the day, then it will only last about 2 years. However, in a "power" application, where the battery is barely discharged, it will last for many thousands of cycles. In fact, this is how it is currently applied. In this case it would be operated like an 8 MW flywheel, with usable energy storage of only about 2 MW hrs.

So how do you value these installations? If we value the flywheel and the li-ion systems by the MW hr, then their cost is $13.8 million and $12.5 million respectively. However, if all we care about is their power capacity, then the cost is $3.45 million and $3.125 per MW. (The NGK battery is the only energy oriented technology mentioned in the article, but no cost information was provided.)

By contrast, a VRB-ESS (vanadium redox flow battery - energy storage system) will provide both energy and power, with nearly unlimited cycles, full or partial, for about the same cost per MW of the flywheel or li-ion battery. However, the VRB-ESS will also include 4 - 8 hours of storage, dropping the cost per MW hr to a fraction of the cost for a "power oriented" system.

For example, a 5 MW system with 6 hours of storage would cost about $18 million, with all costs included - a complete turn-key system. That would provide 30 MW hrs of energy at a cost of about $600 thousand per MW hr. The cost of power is only $3.6 million per MW.

Although not directly relevant to the discussion, it's good to know that the VRB-ESS will last 10 years before needing refurbishment. This consists of replacing the PEM (proton exchange membrane) at a cost of about $3 million. The system is then good for another 10 years!

Bottom-line? - It's important to understand the application, whether energy, power or both, and then determine the cost per energy (MW) and/or the cost for power (MW hr), when evaluating the technology.