Energy | July 15, 2009 |
Ill Wind Blows Over Storage Market
When it comes to discussing the "need" for storage to supplement intermittent wind energy, industry professionals are of two very different minds. The majority of wind energy development companies we've spoken with say there's no need for storage; any limitations in the ability to distribute wind power are due to a lack of transmission infrastructure. By contrast, many energy insiders say storage could make the business case for wind even stronger. Objective analysis indicates that while need may be too strong of a word, in many cases storage would greatly benefit wind.
The American Wind Energy Association (AWEA), has taken a firm position against storage, especially onsite at wind generation facilities. According to the recent Pike Research report by David Link entitled Energy Storage Technology Markets, "...The association’s official position is that storage systems are not required to integrate wind energy into electric power systems.... AWEA’s reticence comes down to simple economics, as developers do not want to bear the additional cost of storage, on top of the cost they are already bearing to deploy core wind generation assets.
This posture is understandable, if not exactly correct. After decades of development, wind power is now approaching the cost of fossil fuel energy in many locations (grid parity), so wind developers don't want to scare investors or lending institutions into thinking that storage is required. That much is true in some cases, especially if you don't care about unutilized power generation that's well, gone with the wind.
At the Storage Week conference, we heard many stories about wind projects that are only harnessing a fraction of the available wind because of low demand at night or insufficient transmission capabilities. Brett Perlman, a former Commissioner from the Texas PUC and now Vice President of Strategy and Development at Atreides Capital, said wind farms in West Texas have a 9 gigawatt capacity, but 4 gigawatts of the wind can't get back to the grid. Just imagine all that energy being wasted, while during the day natural gas and coal plants are in full effect to meet peak demand.
An analogy that springs to mind since it's July -- you don't "need" a bathing suit to cool off in a fountain on the way home from work, but isn't it preferable to walking or riding the rest of the way in a soggy suit?
Perlman says the problem in Texas is insufficient transmission -- an easy argument to make because while sometimes true, power producers usually don't foot the bill and have a strong aversion to even mouthing the world "storage" when they are looking for project funding. Negotations often require transmission commitments to match the wind project before going forward.
Conversely, Dr. Imre Gyuk the DOE's Program Manager for Energy Storage Research (hence a self interest in promoting storage) told of Japanese wind farms that don't put any of their power on the grid at night, instead storing it all and selling the power during peak hours. And they're profitable.
Stephen Byrd, the Chief Economic Officer of Energy Storage and Power, gave another indirect example of why wind companies may be down on storage: its growth could also help to delay the end of some coal power production. Byrd cited instances that in places where wind energy is plentiful during off-peak hours, coal plants (because of CO2 emissions) are being spun down or even mothballed at great cost to their operators so that the maximum amount of wind power is consumed. If storage were available, then the excess energy could be stored and used at peak, with a very low CO2 footprint.
Rather than looking for a yes or no answer, it's best to ask the economic questions to see if they add up. What is the model for cheap and abundant off-peak wind to be stored and sold during peak times? What can be paid per megawatt of storage capacity to turn a profit?
An even more challenging question is: at what point is it better to invest in storage as an alternative to adding transmission lines? In simplistic terms, if you build the transmission line to meet the maximum wind output, you've overbuilt for what you need during the vast majority of the day. But if you build smaller lines and add some storage, you might get greater efficiency.
The biggest related question of them all has yet to be studied: how does the cost per megawatt of storage equate to cost per megawatt per mile of transmission lines, and what's the relative energy efficiency when including losses? Several attendees of the conference asked questions around the periphery, and all agreed that no one -- EPRI, DOE, AWEA, etc, has tried to tackle it, partially because of the complexity of the model due to a plethora of variables.
I spoke with Gary Tarplee, Managing Director of Edison Mission Energy, which develops wind and solar projects around the country. He admitted that "Wind needs storage... but developers don't want to pay for it. They don't want its cost to be associated with their cost."
So if the wind industry is afraid to ask the question, perhaps third party storage companies will. Tarplee agreed that there may be a business case for third-party companies to buy excess wind at night, store it, and sell it during the day. Which leads to questions for another day: Where should the storage be located? At the wind farm? At substations? Closer to the edge?
John Gartner is the editor in chief of Matter Network and an industry analyst for Pike Research
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Why not consider clean coal technology? During the America’s Power Factuality Tour, we stopped by Duke Energy’s Edwardsport IGCC plant in Indiana and saw Duke’s clean coal technology project for ourselves. Once it’s completed (it’s on schedule for 2012), this IGCC plant will be one of the cleanest coal-based power plants in the world, producing 10 times as much power as the existing unit with 45 percent less carbon dioxide emissions per unit of energy produced. http://sn.im/factuality5
some research is available re-storage vs.transmission for wind integration. see - http://www.usaee.org/usaee2009/submissions/Presentations/SFPaul.pdf
Estimating the Transmission Value of Combining Wind with Energy Storage
Paul Denholm
National Renewable Energy Laboratory
Sioshansi Ramteen
The Ohio State University
These are not "questions for another day". The question has already been answered. You ask, "where should the storage be located? At the wind farms? At substations? Closer to the edge?" The answer is none of these, and has already been in widespread use for years!
Electric Thermal Storage Heating(ETS)is an existing space heating technology that converts electricity into heat which is stored in a thermally insulated brick storage mass located at the point-of-use for distribution at a later time. ETS is and has been in use throughout the northern US for many years, and in Europe for over 50 years.
In the words of Paul Steffes,P.E., CEO of Steffes Corporation which manufactures ETS heating systems, ETS is "A distributive electric storage technology that is a
low cost, long life renewable thermal battery for wind-generated electricity” that absorbs peak wind energy at night, and stores it at the point of use as heat for distribution when needed. ETS is a proven technology has been in widespread use for 50 years. Over 200,000 homes presently use ETS in the US.
So, what's the big fuss about? Problem solved! Please contact Paul Steffes, P.E. at the Steffes Corporation, www.steffes.com for more information on the synergy between wind and ETS heating.
These are not "questions for another day". The question has already been answered. You ask, "where should the storage be located? At the wind farms? At substations? Closer to the edge?" The answer is none of these, and has already been in widespread use for years!
Electric Thermal Storage Heating(ETS)is an existing space heating technology that converts electricity into heat which is stored in a thermally insulated brick storage mass located at the point-of-use for distribution at a later time. ETS is and has been in use throughout the northern US for many years, and in Europe for over 50 years.
In the words of Paul Steffes,P.E., CEO of Steffes Corporation which manufactures ETS heating systems, ETS is "A distributive electric storage technology that is a
low cost, long life renewable thermal battery for wind-generated electricity” that absorbs peak wind energy at night, and stores it at the point of use as heat for distribution when needed. ETS is a proven technology has been in widespread use for 50 years. Over 200,000 homes presently use ETS in the US.
Problem solved! So, what's the big fuss about? Please contact Paul Steffes, P.E. at the Steffes Corporation, www.steffes.com for more information on the synergy between wind and ETS heating.
The Mechanics of Wind TurbinesModern electric wind tbeiunrs come in a few different styles and many different sizes, depending on their use. The most common style, large or small, is the "horizontal axis design" (with the axis of the blades horizontal to the ground). On this turbine, two or three blades spin upwind of the tower that it sits on.Small wind tbeiunrs are generally used for providing power off the grid, ranging from very small, 250-watt tbeiunrs designed for charging up batteries on a sailboat, to 50-kilowatt tbeiunrs that power dairy farms and remote villages. Like old farm windmills, these small wind tbeiunrs have tail fans that keep them oriented into the wind.Large wind tbeiunrs, most often used by utilities to provide power to a grid, range from 250 kilowatts up to the enormous 3.5 to 5 MW machines that are being used offshore. Today, the average land-based wind tbeiunrs have a capacity of 1.5 MW.[7] Large tbeiunrs sit on towers that can be anywhere from 50 to 100 meters tall, and have blades that range from 30 to 50 meters long.[8] Utility-scale tbeiunrs are usually placed in groups or rows to take advantage of prime windy spots. Wind "farms" like these can consist of a few or hundreds of tbeiunrs, providing enough power for tens of thousands of homes.From the outside, horizontal axis wind tbeiunrs consist of three big parts: the tower, the blades, and a box behind the blades, called the nacelle. Inside the nacelle is where most of the action takes place, where motion is turned into electricity. Large tbeiunrs don't have tail fans; instead they have hydraulic controls that orient the blades into the wind.In the most typical design, the blades are attached to an axle that runs into a gearbox. The gearbox, or transmission, steps up the speed of the rotation, from about 50 rpm up to 1,800 rpm. The faster spinning shaft spins inside the generator, producing AC electricity. Electricity must be produced at just the right frequency and voltage to be compatible with a utility grid. Since the wind speed varies, the speed of the generator could vary, producing fluctuations in the electricity. One solution to this problem is to have constant speed tbeiunrs, where the blades adjust, by turning slightly to the side, to slow down when wind speeds gust. Another solution is to use variable-speed tbeiunrs, where the blades and generator change speeds with the wind, and sophisticated power controls fix the fluctuations of the electrical output. A third approach is to use low-speed generators. Germany's Enercon tbeiunrs have a direct drive that skips the step-up gearbox.An advantage that variable-speed tbeiunrs have over constant-speed tbeiunrs is that they can operate in a wider range of wind speeds. All tbeiunrs have upper and lower limits to the wind speed they can handle: if the wind is too slow, there's not enough power to turn the blades; if it's too fast, there's the danger of damage to the equipment. The "cut in" and "cut out" speeds of tbeiunrs can affect the amount of time the tbeiunrs operate and thus their power output.There is a great picture on the web site, plus all sorts of other good information.
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