Wind Shortfalls Make Grid Guys Nervous
When it comes to integrating wind into the transmission lines, system operators say that they are challenged. While they understand and appreciate the reasoning, they are saying that the networks lack the flexibility to handle wind variation.
Green energy has a lot of public appeal. But the intermittent nature of wind and solar power coupled with the relatively higher costs put the grid’s traffic cops in an untenable position. Those are the fellows whose job it is to schedule the resources to where they need to be so that the electricity keeps flowing. Their task is to maintain that reliability with the lowest-priced fuels.
“We have to be truthful about what the impact will be,” says Jim Detmers, principal in Power Systems Resources and the former chief operating officer of the California ISO. “The devil is in the details. These new embedded costs will be significant.” Better communication with policymakers is essential.
In the case of California, it now has 3,000 megawatts of wind. In a few years, that will be 7,000 megawatts. A few years later, it will be 10,000 megawatts. By 2020, the goal is to have 33 percent of electricity generated from renewable energy. “That’s making grid operators nervous,” says Detmers, who spoke at Wartsila’s Flexible Power Symposium in Vail, Colo.
Simply, the wind does not blow on demand. Ditto for the sun. So these resources must be backed up with other, “dispatchable” forms of generation. But such “firming” or “cycling” creates two distinct issues: The first is that the power is not free and the second is that if coal plants are “cycled” up and down, they release more pollutants per unit of output than if they ran full steam ahead.
No doubt, the price of wind and solar energy is falling while their productivity rates are increasing. But the technologies still have a ways to go.
“If you are a grid operator, you must be dispassionate and follow the engineering,” says David O’Brien, former head of the Vermont’s Department of Public Service and now a consultant for Bridge Energy Group, during a phone call. “The best thing they can do is to provide the data to their stakeholders and to be an honest broker. But they have to ultimately accept the policy mandates.”
Public Demands
According to Steve Lefton, director of Intertek Aptek who also spoke at the Wartsila conference, those base-load coal units developed decades ago were never designed to firm-up wind generation. They were made to run at full capacity. So when they are used as such, they create excess emissions.
As wind energy increases its market share, thermal plants can be expected to rev up and down more often. If coal is the main fuel source that is dispatched, it will decrease the emissions savings from wind.
“The actual emissions reduction rates from wind are far less than what the lobbyists are touting,” if system operators do not have the flexibility to use cleaner backup fuels, says Brannin McBee, energy analyst for Bentek Energy, a speaker at the conference. “Thermal plant cycling is also very expensive,” particularly if the older coal plants are used to firm up the wind generation.
With the public demands to increase green energy growing, what might be an optimal firming fuel? The answer could be natural gas. Regulators tend to favor it because it releases far fewer emissions than coal while the price is expected to remain low at $4-$7 per million BTUs.
Coal facilities without carbon capture and sequestration cannot get the permits to operate, says Doug Egan, chief executive of Competitive Power Ventures. And if the plants are built with such capacity they are too costly. Even those with coal gasification that nearly eliminate the sulfur, nitrogen oxide and mercury but which don’t capture and bury the carbon are prohibitively expensive, he adds.
In recent years, developers have abandoned their plans to build 38 coal plants, says the Sierra Club. Meanwhile, it says that 48 more can be expected to be retired.
Natural gas is the most plausible option to firm up wind and solar. More than enough of it exists with the recent discoveries of shale gas, the unconventional source that is extracted from rocks more than a mile beneath the ground using hydraulic fracturing. That withdrawal technique, though, is under fire from some community organizations that say it is polluting their drinking water.
The U.S. Environmental Protection Agency wants developers to voluntarily disclose the chemicals they are using as a way to ease tensions. Producers are balking for now, saying its exploratory methods are proprietary.
“Fracking can be dealt with,” says Egan. “Producers will share their secret sauce. It will make it the process slightly less efficient. But a deal with get cut.”
Managing a grid and keeping the lights on is difficult. Green energy’s role will increase but so too will the challenges associated with delivering it -- facts that must be relayed to policymakers and customers alike. Older coal plants present the most issues but the newer gas-fired generation may be more accommodating.
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Comments
Distributed Demand Response Schema
Oh, but wait!! Here's a plan...
Google management had a great idea to cope with variability of Wind and Sun. Their idea is to build about a half-dozen server farms, each mirroring the total Google internet database.
Then, Power Management control systems would run the Google processes from whichever farm had wind and sun power available that period.
If that works out well, General Motors could restart all their idled regional assembly plants and use the same management schemes. This concept could revive our economy, with a half-dozen standby jobs on, for instance, half-pay, each being available on short notice to assemble cars and trucks.
some questions
The questions to come out of this discussion are what the price to society and the price to consumers will be if shale becomes the replacment for coal. Will power be more expensive? Will it be better for the environment? For coal to get regulatory approval, it will have to be cleaner. How much more will these investments be? Will that make coal more expensive than shale? What about wind and solar over time? Won't the prices come down and make it more competitive? Will the storage technologies soon be available? If someone can address these questions, it would be very helpful to those trying to make up their mind on this issue. I'm sure that one person does not have all the answers. Thank you.
Energy storage
If wind grows (God forbid!) Into a substantial proportion of the electrical energy needed, then there will be a huge demand or energy storage. People should stop kidding themselves that whole populations, businesses and economies will tailor their daily actions to the whims of the wind. Tthis would cause total chaos, carry huge expenses and make the United States industry and the economy uneconomic. So, if we are to have wind and solar power in large quantities, storage is essential.
People talk about storage in terms of a few hours only. For this, batteries–at great expense–and pumped storage schemes–at a lower expense–can fill the bill. But most pumped storage stations have sufficient storage for 6 to 10 hours operation. But when you look at wind and solar power then, you find that, in many cases, you will have to store energy for days or weeks and even months. Quite clearly, batteries are out and pumped storage is likewise impractical because you need a huge number of sites suitable for building a very large upper storage reservoir and a very large lower storage reservoir and separated by 500 to 700 m. And they have to have a good supply of water to overcome the evaporation losses. There are two or three such schemes in the world and, as I understand, they rely on natural lakes. On top of that, pumped storage scheme and earns its money by working hard every day. A seasonal pumped storage scheme pumps for a few months and then generates for a few months. So even if it were cheap to build–and won't be–it will still be extremely expensive storage.
But why are we worrying about all these things? United States–and, soon, much of the world–now has access to truly enormous quantities of gas from shale. This provides all the additional energy we could meet in the future and also allows for the phasing out obsolete coal-fired stations.
But then you have to ask another question. What are we trying to achieve? If it is a reduction of carbon dioxide emissions in order to “fight global warming" the battle is over. Every day more evidence accumulates that man-made carbon dioxide has nothing to do with the world climate. Every day, evidence accumulates that the world has entered a cooling phase and, right now, dangerous global cooling is what we should be preparing for. And that will mean more electricity and energy will be used in heating and that, inevitably, food production will reduce. Both of these are extremely serious.
So let us forget all this nonsense about windpower, renewable energy and global warming and concentrate on what really matters. Global cooling.
My name is Tom Stacy
First, Thank you to Ken for repeatedly presenting this issue to your readers over time. As well, I appreciate your very balanced perspective. I have spent the past three years networking with energy and policy professionals on this very issue - but starting completely "green" (as in 'noob'). Today I spend considerable time preparing and delivering presentations on the issue to interested parties - all unfunded, and all for free. Why? Because I love America's values and am proud of our global leadership over the past two + centuries. I just want us to not further abandon the sensibilities that won us this prestige.
Clearly the laws of physics cannot be rewritten to accommodate well intentioned and grounded ideals - that we'd be better off using sources of energy that aren't limited over a century or less time horizon, and which aren't environmentally perilous. But unfortunately the details do harbor the devil here, and it is simply not fair to taxpayers or rate payers to pursue this ideal using technologies that cannot respond to market signals - in hopes a breakthrough in energy storage capacity and affordability is just around the corner. Complete solutions must be arrived at in a limited setting, and vetted for their technical, environmental and economic performance BEFORE our government spends money from the taxpayer's wallet to deploy them on a large scale.
This is not a game we can start over twenty years from now because we aren't winning. Today's policy decisions weigh heavily on America's future global competitiveness across the board, just like low transcontinental transportation costs inadvertently put our labor force at a competitive disadvantage. The difference is, with wind energy, some are attempting to have us voluntarily give up our competitive edge in electrical energy value.
The finger needs to be pointed squarely at law makers who must put on their big boy (and girl) pants, and make energy policy decisions to support complete generation solutions - behind the interconnection transformer. If that means building a gas plant (wartsila piston engine or a CCGT or a simple cycle combustion turbine) on the sprawling campus of every wind generation colony, then so be it. The land use / sprawl implication will not suffer, the product wind+gas will be as schedulable and responsive as every conventional generator in the nation wide fleet, and the rules can remain constant.
As a bonus, we will be able to accurately measure the heat rate implications of ramping and partial loading to accommodate wind, and learn just exactly how clean, green and affordable the wind energy "solution" is. In the end we have to apply metrics to value. But this is impossible when the service bundle of electricity generation includes not just quantity, but also logistics and delivery timing obedience, and the wind lobby has Congress convined that raw MWH production - regarless of when, where, or for how long - is the only metric of value.
Public support
Hi, this is Ken. I've received a number of questions about how I quantify 'public support' for green energy and if I have them, to please provide specific poll numbers. First, I skeptical of polls taken randomly from the public. That's because the question is usually slanted to get the response the organization funding the poll wants. Having said that, what one can say is that at least half the states have enacted renewable portfolio standards. And because we live in a representative democracy, one can generally conclude that our officials would not proceed unless they have either the implicit or explicit backing of the people. I know the responses that will come in: "But the people don't truly understand the shortcomings of green power, namely the variable nature." I get it. But the point of the article is to show that states are under these mandates and grid operators must comply with them. So the questions are: Do we revert back and use older generation or do we look forward and try to come up with solutions? In this story, I present one of the solutions that some of the panelists at the Wartsila conference had espoused: gas-fired plants that are cleaner than coal and which can ramp up rather quickly to back up wind if it stops blowing. Ken
Wind shortfalls make grid guys nervous
In response to Tom Casten’s excellent comment, I can only proffer the age-old adage, “You can take the horse to water, but you can’t force it to drink”. But, since we desperately need that horse we must find alternative ways to hydrate the critter!
Wind shortfalls make grid guys nervous
The problems described are largely caused by using yesterday's technology and yesterday's monopoly utility objection to distributed generation. The grid and its utilities can accomodate more sustainable energy, including wind with proven technology by embracing distributed generation and thinking in a DG paradigm.
First, end the logic flaw. Because all A is B does not mean that all B is A. All electricity generated with renewable energies is sustainable, but sustainable energy is not solely from renewable energies. Generating electricity by recycling process waste energy is also sustainable, in that it does not deplete the base capital of the planet or cause any incremental ecological problems. California should follow the lead of 10 other states in recognizing waste energy recovery or WER as sustainable, for several reasons, including helping to accomodate more wind energy, which brings us to the second point.
The deployment of WER helps achieve the societal goal of increasing sustainability. Waste energy flows tend to be 24/7, so WER generation is base load, as opposed to solar and wind generation. Thus WER does not present shortfall problems to the grid.
The WER projects are almost totally located at or next to electric users, so WER generation reduces the flow through the T&D system, and frees the wires to carry more wind power.. Regardless of who purchases the WER electricity, the electrons flow to nearest user. Without grid control of WER voltage or leading/lagging power factor, the local WER generation avoids the U.S. average, the 6.5% line losses on the WER power , and by lowering the current flow on the remaining centrally generated power, lowers the line losses of all remaining T&D flows.. Counting both impacts, local DG of one MWH, without voltage control by the grid, avoids about 1.13 MWh of central generation and so eliminates 130 kWh of line losses.
But grid operators would kill for the active power factor and voltage control they cannot obtain from their passive capacitance and inductance banks. Grid operators can have this dream from DG that uses spinning generators (not so easy with DG power that flows through an inverter, as from solar collectors). Dr Marija Ilich, professor of electric engineering at MIT and Carnegie Mellon has shown that one MWh of DG, located in a load pocket (where there are manufacturing plants emitting waste energy streams) can, with grid control of leading or lagging power factor, avoid up to 1.45 MWh on average, and up to 2.25 MW of peak generation. The long-practiced central generation paradigm blinds grid operators to this option and has them believing the only way to active PFcontrol is with expensive FACTS type capacitors.
These two elements - adding 24/7 sustainable generation from WER projects and then using the WER for active PF control greatly lowers the problems of Wind variability and lowers the cost of sustainble energy. But there is more help available from enlightened new CHP.
The current central generation approach is to build gas turbine electricity-only generator plants for peak shaving, and then operate these turbines very inefficiently at part loads through the on-peak hours, giving grid operators spinning reserve to compensate for loss of generation, whether the loss is due to calming winds or due to failure of a fossil or nuclear generation plant. These pathetic peaking plants burn over 13,000 Btus of natural gas per kWh all day long, in order to provide spinning reserve, and do not provide spinning reserve during off peak, when they are turned off. Wind shortfalls during off peak hours are managed by keeping added Ranikne cycle plants on line that are operating at part load, with efficiency penalties, which also wastes fuel, increasing polllution and expense.. Policy makers are then asked to allocate these added expenses to wind costs, which slows the march to a sustainable future. But there is a more elegant sollution involving DG.
Encourage new CHP plants using gas turbine generators that are oversized for the host thermal requirement , and then operate these plants around the clock, but only generating enough electricity to supply the host thermal need. For example, install a GE LMS 100 with roughly 100 MW of capacity, to provide a 120,000 pound steam load for a bypical industrial plant such as ethanol, beef or poultry processing, chemical manufacture, etc. Operate the turbine at about 40 to 45 MW to produce sufficent exhaust heat to supply the steam load. The net fuel to electricty is just over 5,000 Btu per kWh, a heat rate that is way lower than the best combined cycle gas turbine plant's 7,000 Btu heat rate.. The remaining 60 MW of capacity can ramp up and provide spinning reserve, 24/7, eliminating both present grid problems. The incremental heat rate to ramp us this turbine is about 7,100 Btu/kWh, still very efficient.
It gets better. Because the new CHP plants will nearly always be next to industrial electric loads, these plants reduce line losses, as noted above. The grid operator, by controlling the CHP generation power factor to provide active VAR support can slash peak generation and T&D requirements. If wind generation dropped by 120 MW during peak hours, one CHP/spinning reserve plant would supply an instant 60 MW of generation and would cut system line losses by 60 to 75 MW, thus covering the entire wind shortfall.
ThisCHP/spinning reserve approach eliminates the cost of inefficiently operating a 200 MW peak shaver at 40% minimum load for ten to twelve hours per day to provide the same 120 MW of spinning reserve. It also reduces the need to add transmission lines as load grows.
Wind variability is real and does require system response. Conventional approaches to managing wind variability are only expensive if we stick with last century's technology and yesterday's anti-DG attitudes of monoppoly protected generatiors. Wind and waste energy recovery systems or WER projects complement each other, speeding the march to sustainability and lowering its cost.
Tom Casten, Chair
Recycled Energy Development LLC.
tcasten@recycled-energy.com
I hope our "experts" listen
One can only hope the "experts" at DOE, EPA and NREL and our legislators read and heed Mr. Casten's post above. His approach is sensible and will lead to less wasted fuel, lower emissions, and lower power costs. Think about the net effects of building simple cycle gas turbines for back up of a large wind farm, especially if it they are build at the wind farm site. First their heat rate will be lousy because there is no heat recovery and they will spend much of the time at part load. Second, the line losses from pumping the power hundreds of miles will make the delivered heat rate even worse--ie more CO2 and other emissions per MWh generated.
new pumped storage is a key
The article suggests that natural gas is the most plausible way to "firm up" wind and solar. This is not true in many areas of intensive wind and solar development, where a number of firms - led by Gridflex Energy - are proposing new pumped storage and CAES (compressed air energy storage) projects that can represent a superior strategy to gas turbines. Combustion turbines can only "fill in the space" on the transmission lines, and they must do so by burning a fossil fuel that has greenhouse gas emissions and always faces future price uncertainty (current perception of glut notwithstanding). Pumped storage projects with sufficient storage capacity, like those being proposed, can firm wind with wind and create firm products that can compete against any other firm intermediate-to-baseload resource. Unlike combustion turbines, pumped storage can also peak-shave, creating huge savings on transmission costs by absorbing the top MW production and shifting it to times of lower wind (or solar) production. Pumped storage plants can ramp up and down much faster than even the next generation of combustion turbines, without the issues of increased O&M and decreased efficiency that fossil plants face when serving in this function. The key to making it work is optimizing the balance between wind (or solar) and storage capacity so that you get the greatest bang for your buck. You also have to find the most cost-effective sites to use, since pumped storage costs vary widely from site to site. Gridflex has largely addressed this question as well.
Grow up and go to work.
Now is the time for progress, not saying "tell me how to do my job", posturing for higher fees to please Wall Street, and saying "lets just run coal plants because we know how to do that. Lets throw the entire operation back to the 1950's and remove computers, and rely on the telephone for notifications of changes. Perhaps automation that eases power regulation made the dispatcher's job just too easy.
I seriously question the compentency of the those making statements about more difficult operations: they are the experts, now propose a solution. Integrate weather forecasts for wind and sunlight into the dispatch model. Run a computer simulation to select best practices and monitor the changes. The prevailing "anti-change" model must give way to real improvements. If they cannot perform the job, then I'm sure others are available that will be quite willing to replace them. Put on your big boy pants and grow up and go to work.
I need more info
These older coal plants have all been "depreciated" over the years, right? The purpose of that was to be able to offset upgrades, replacement of the facilities when they have come to the end of their useful life, right? Where is all that money now?
Where is the energy storage discussions or plans for these intermittent power sources? Would that not make it easier to coordinate and distribute?
Why do I keep reading its up to the "regulators" to figure it out? I'm just getting tired of the finger pointing, procrastination and various gyrations of the same. Companies need to make money, I get it. Producing power isn't free or cheap, no problem there either. But come on, the electric energy industry (generation and delivery) have got to make changes to the way they think, manage etc to get all this to work. Lot's of folks way smarter than me are supposed to be working on this stuff, do you think us "consumers" really believe the electric industry didn't see this coming?
There, a stone has been thrown? What ripples will there be?
EXPENSE LAYERED ON EXPENSE
Except for the comment, "With the public demands to increase green energy growing...", which I think well overstates the interests of "the public"...good article.
What I'm hearing is that to make wind & solar really work, one costly technology has to be layerd on top of another....repeat till bankrupt.
First comes the actual wind or solar installation....expensive. Add transmission lines to connect the remote generation sites to the load centers....more cost. Add Smart Grid technology to accommodate the reliability issues...more cost. Add "storage" (at some point) to augment the Smart Grid....more cost Add DR to work out local kinks....yet more cost.
I hear/see very, very little assessment of the net-net costs related to "energy independence the renewable way". For the longest time I think a lot of us thought the "novelty" of the early wind/solar projects might hold future promise....but it's time to get serious. The real net-net costs AREN'T coming down and we've had a LONG time to assess this trend. The notion that better technology is right around the corner is at very best wishful thinking. Nevermind....but for the objections of a few engineers, we're hell bent toward a third world energy system not unlike something you might expect in a Central American country.
Exactly How Wise is the 33% Mandate?
Let's see if I have the math correct. If the rule in California is to achieve a goal of 33% or electricity from wind and the best capacity factor achieved for land-based wind is about 30 to 32%, then there must be installed enough wind to equal the average demand in California--actually a tad more--or, California must install more wind capacity than average demand and idle wind farms during high wind/low demand times. Meanwhile, they must keep online sufficient nuclear, conventional, or peaking power to stabilize the grid due to the highly erratic output of wind turbines and provide backup.
So, if California invests in 10,000MW of wind, they will also need to invest in or retain in operation 10,000MW of conventional power as backup for a wind system which will actually put out varying amounts of power only about 60% of the time and which will, relatively speaking, rarely reach nameplate capacity and which, at times, will be required to idle wind capacity in order to have a stable grid.
Wind cannot be depended on to be available when needed.
That wind system will also use about 10 times the amount of steel and 6 times the amount of concrete needed to build a combination of nuclear facilities of 10,000MW. If you look at it from a annual delivered energy standpoint, the wind facilities will require about 30 times the amount of steel and 18 times the amount of concrete it would take to construct 3,333 MW nuclear facilities to deliver the same amount of MWh. Not to mention how much more land will be occupied by the wind facilites. The amount of construction materials needed for wind versus fired conventional or combined cycle facilities presents an even more dramatic contrast.
What a brilliant policy!
Square Pegs in Round Holes
Powering continuous processes with discontinuous sources of power doesn't make any sense at all, physically or economically.
Perhaps manufacturers could shift production to the late second and early third shifts, when the wind tends to blow. The employees could take their breaks when the wind diminished, then work twice as fast when the wind picked up again.
Other users could continue to "do their thing" during the day, when the sun tends to shine.
Children could do some of their homework immediately after school, using available light, go to sleep for a while, then be awakened when the wind began to blow to fininsh their homework.
Ah, the wonders of Demand Response!
What about Demand Response ?
When the wind goes does, one can expect the load to be managed to be reduced ? And stimulate Demand when there is an excess of wind. DR aggregators mignt be able to do this job, mignt they not ?
to whoever posted "What about
to whoever posted "What about Demand Response ?
When the wind goes does, one can expect the load to be managed to be reduced ? And stimulate Demand when there is an excess of wind. DR aggregators mignt be able to do this job, mignt they not ?"
What? When wind goes does? Might they not? Holy cripes Shakespeare, your post is written so poorly. Seriously, please do not post again.
Sorry double comment
Sorry double comment