Energy Efficiency of Power Production: How Supercritical Carbon Dioxide Turbines Operate

Posted on September 1, 2018 by duanetilden

Duane M. Tilden, P.Eng.                                    Sept 1, 2018

Foreword:

This is another article in an ongoing series of reports on the technological development of supercritical carbon dioxide in the power production and energy efficiency sectors of industry, power plants and utilities.

dodge-sco23 supercritical CO2 turbine

Figure 1. Size comparison of Supercritical Power Turbine to Conventional Steam Turbine (1)

Abstract:

The ever increasing search for improving energy and power production efficiency is a natural quest as developments in technology seek to be utilized to improve operations and supply cost effectively. The technologies behind the utilization of supercritical carbon dioxide and other such fluids have long been established. We are furthering our exploration into this sector of power production developing new technologies along the way to a smarter economy and modernization of infrastructure.

The Principle of Operation

Supercritical fluids can play an important role in developing better electricity generators because of their liquid- and gas-like properties. A supercritical fluid is an optimal working fluid because it has a temperature and pressure above its critical point, meaning that it doesn’t have a definite liquid or gas phase. Consequently, the slightest changes in pressure or temperature cause huge changes in the material’s density.

With any supercritical fluid, the ease of compressibility goes up, explains Stapp, so it becomes something more like water. Because supercritical CO2 also compresses more easily than steam, the amount of work done during the compression phase—normally accounting for 25 percent of the work performed inside the system—is dramatically reduced; the energy saved there greatly contributes to the turbine’s overall efficiency.

“We expand it like a gas, and pressurize it like a liquid,” says James Pasch, principle investigator of the Supercritical Carbon Dioxide Brayton Cycle Research and Development Program. “You can do this with any fluid, but supercritical carbon dioxide matches really well with ambient temperatures.”

Carbon dioxide is optimal for this application because it doesn’t go through a phase change at any point during the cycle. Its critical temperature, 88 degrees Fahrenheit, is very close to ambient temperature, which means the heat emitted by the turbine is the same temperature as the surrounding environment. Supercritical carbon dioxide is also very dense; at its critical point, the fluid is about half the density of water. So, in addition to being easier to compress, less work is required to cycle it back to the heat source for re-expansion.

The Brayton Cycle also offers direct environmental benefits. For one, it’s carbon neutral. The system takes carbon dioxide out of the air and puts it in the recompression cycle loop. Just as important is the fact that the system limits water usage by minimizing discharge, evaporation, and withdraw.

“That’s a big deal for the southwest,” says Gary Rochau, manager of Sandia’s Advanced Nuclear Concepts Department. Sandia’s generator can work in places where water is in limited supply. This puts it on par with the Palo Verde Nuclear Power Generating Station, a nuclear power plant in Arizona that uses recycled waste water as cooling water, saving groundwater and municipal water supplies for other uses. (2)

Figure 1. Illustration of a Supercritical CO2 Turbine [Peregrine Turbine Technologies] (2)

Advances in Materials and Technology

GE Reports first wrote about Hofer last year when he 3D printed a plastic prototype of the turbine. His team, partnered with Southwest Research Institute and Gas Technology Institute, has since submitted the design to the U.S. Department of Energy and won an $80 million award to build the 10 MW turbine. The turbine features a rotor that is 4.5 feet long, 7 inches in diameter, and only weighs 150 pounds. The engineers are now completing a scaled-down, 1 MW version of the machine and will test it in July at the Southwest Research Institute.

The idea of using CO2 to power a steam turbine has been around for a while. It first appeared in the late 1960s, and an MIT doctoral student resurrected it in 2004. “The industry has been really interested in the potential benefits of using CO2 in place of steam in advanced supercritical power plants,” Hofer says.

By “supercritical” Hofer means efficient power stations using CO2 squeezed and heated so much that it becomes a supercritical fluid, which behaves like a gas and a liquid at the same time. The world’s most efficient thermal power plant, RDK 8 in Germany, uses an “ultrasupercritical” steam turbine operating at 600 degrees Celsius and pressure of 4,000 pounds per square inch, more than what’s exerted when a bullet strikes a solid object.

Hofer says that the steam power plant technology “has been on a continuous march” to increase efficiency and steam temperature, but once it tops 700 degrees Celsius, “the CO2 cycle becomes more efficient than the steam cycle.” Hofer’s turbine and casing are made from a nickel-based superalloy because it can handle temperatures as high as 715 degrees Celsius and pressures approaching 3,600 pounds per square inch. “You need a high-strength material for a design like this,” he says.

Figure 2. GE Global Research engineer Doug Hofer is building a compact and highly efficient turbine that fits on a conference table but can generate 10 megawatts (MW), enough to power 10,000 U.S. homes. The turbine, made from a nickel-based superalloy that can handle temperatures up to 715 degrees Celsius and pressures approaching 3,600 pounds per square inch, replaces steam with ultrahot and superpressurized carbon dioxide, allowing for a smaller design.

The hellish heat and pressure turn CO2 into a hot, dense liquid, allowing Hofer to shrink the turbine’s size and potentially increase its efficiency a few percentage points above where state-of-the-art steam systems operate today. “The pressure and fluid density at the exit of our turbine is two orders of magnitude higher than in a steam turbine,” Hofer says. “Therefore, to push the same mass through, you can have a much smaller turbine because the flow at the exit end is much denser.”

Hofer’s design uses a small amount of CO2 in a closed loop. “It’s important to remember that this is not a CO2 capture or sequestration technology,” he says. Hofer says that the technology, which is being developed as part of GE’s Ecomagination program, could one day start replacing steam turbines. “It’s on the multigenerational roadmap for steam-powered systems,” he says.

By virtue of becoming more efficient, the technology could help power-plant operators reduce greenhouse gas emissions. “The efficiency of converting coal into electricity matters: more efficient power plants use less fuel and emit less climate-damaging carbon dioxide,” wrote the authors of the International Energy Agency report on measuring coal plant performance. (3)

Previous Blog Posts on Supercritical Carbon Dioxide:

References:

A Modern Renaissance of Electrical Power: Microgrid Technology – Part 1

Posted on May 1, 2017 by duanetilden

Figure 1: The original Edison DC microgrid in New York City, which started operation on September 4, 1882 (1)

A. Historical Development of Electric Power in the Metropolitan City

The development of electricity for commercial, municipal and industrial use developed at a frantic pace in the mid to late 1800’s and early 1900’s. The original distribution system consisted of copper wiring laid below the streets of New York’s east side. The first power plants and distribution systems were small compared to today’s interconnected grids which span nations and continents. These small “islands” of electrical power were the original microgrids. In time they grew to become the massive infrastructure which delivers us electrical power we have become dependent upon for the operation of our modern society.

1) Let There Be Light! – Invention of the Light Bulb

When electricity first came on the scene in the 1800’s it was a relatively unknown force. Distribution systems from a central plant were a new concept originally intended to provide electric power for the newly invented incandescent light bulb. Thomas Edison first developed a DC power electric grid to test out and prove his ideas in New York, at the Manhattan Pearl Street Station in the 1870’s. This first “microgrid” turned out to be a formidable undertaking.

[…] Edison’s great illumination took far longer to bring about than he expected, and the project was plagued with challenges. “It was massive, all of the problems he had to solve,” says writer Jill Jonnes, author of Empires of Light: Edison, Tesla, Westinghouse, and the Race to Electrify the World, to PBS. For instance, Edison had to do the dirty work of actually convincing city officials to let him use the Lower East Side as a testing ground, which would require digging up long stretches of street to install 80,000 feet insulated copper wiring below the surface.

He also had to design all of the hardware that would go into his first power grid, including switchboards, lamps, and even the actual meters used to charge specific amounts to specific buildings. That included even the six massive steam-powered generators—each weighing 30 tons—which Edison had created to serve this unprecedented new grid, according to IEEE. As PBS explains, Edison was responsible for figuring out all sorts of operational details of the project—including a “bank of 1,000 lamps for testing the system:” (1)

Although Edison was the first to develop a small DC electrical distribution system in a city, there was competition between DC and AC power system schemes in the early years of electrical grid development. At the same time, there were a hodge-podge of other power sources and distribution methods in the early days of modern city development.

In the 1880s, electricity competed with steam, hydraulics, and especially coal gas. Coal gas was first produced on customer’s premises but later evolved into gasification plants that enjoyed economies of scale. In the industrialized world, cities had networks of piped gas, used for lighting. But gas lamps produced poor light, wasted heat, made rooms hot and smoky, and gave off hydrogen and carbon monoxide. In the 1880s electric lighting soon became advantageous compared to gas lighting. (2)

2) Upward Growth – Elevators and Tall Buildings

Another innovation which had been developing at the same time as electrical production and distribution, was the elevator, a necessity for the development of tall buildings and eventually towers and skyscrapers . While there are ancient references to elevating devices and lifts, the original electric elevator was first introduced in Germany in 1880 by Werner von Siemens (3). It was necessary for upward growth in urban centers that a safe and efficient means of moving people and goods was vital for the development of tall buildings.

Later in the 1800s, with the advent of electricity, the electric motor was integrated into elevator technology by German inventor Werner von Siemens. With the motor mounted at the bottom of the cab, this design employed a gearing scheme to climb shaft walls fitted with racks. In 1887, an electric elevator was developed in Baltimore, using a revolving drum to wind the hoisting rope, but these drums could not practically be made large enough to store the long hoisting ropes that would be required by skyscrapers.

Motor technology and control methods evolved rapidly. In 1889 came the direct-connected geared electric elevator, allowing for the building of significantly taller structures. By 1903, this design had evolved into the gearless traction electric elevator, allowing hundred-plus story buildings to become possible and forever changing the urban landscape. Multi-speed motors replaced the original single-speed models to help with landing-leveling and smoother overall operation.

Electromagnet technology replaced manual rope-driven switching and braking. Push-button controls and various complex signal systems modernized the elevator even further. Safety improvements have been continual, including a notable development by Charles Otis, son of original “safety” inventor Elisha, that engaged the “safety” at any excessive speed, even if the hoisting rope remained intact. (4)

Figure 2: The Woolworth Building at 233 Broadway, Manhattan, New York City – The World’s Tallest Building, 1926 (5)

3) Hydroelectric A/C Power – Tesla, Westinghouse and Niagara Falls

Although Niagara Falls was not the first hydroelectric project it was by far the largest and from the massive power production capacity spawned a second Industrial Revolution.

“On September 30, 1882, the world’s first hydroelectric power plant began operation on the Fox River in Appleton, Wisconsin. […] Unlike Edison’s New York plant which used steam power to drive its generators, the Appleton plant used the natural energy of the Fox River. When the plant opened, it produced enough electricity to light Rogers’s home, the plant itself, and a nearby building. Hydroelectric power plants of today generate a lot more electricity. By the early 20th century, these plants produced a significant portion of the country’s electric energy. The cheap electricity provided by the plants spurred industrial growth in many regions of the country. To get even more power out of the flowing water, the government started building dams.” (6)

Figure 3: The interior of Power House No. 1 of the Niagara Falls Power Company (1895-1899) (7)

Figure 4: Adam’s power station with three Tesla AC generators at Niagara Falls, November 16, 1896. (7)

Electrical Transmission, Tesla and the Polyphase Motor

The problem of the best means of transmission, though, would be worked out not by the commission but in the natural course of things, which included great strides in the development of AC. In addition, the natural course of things included some special intervention from on high (that is, from Edison himself).

But above all, it involved Tesla, probably the only inventor ever who could be put in a class with Edison’s in terms of the number and significance of his innovations. The Croatian-born scientific mystic–he spoke of his insight into the mechanical principles of the motor as a kind of religious vision–had once worked for Edison. He had started out with the Edison Company in Paris, where his remarkable abilities were noticed by Edison’s business cohort and close friend Charles Batchelor, who encouraged Tesla to transfer to the Edison office in New York City, which he did in 1884. There Edison, too, became impressed with him after he successfully performed a number of challenging assignments. But when Tesla asked Edison to let him undertake research on AC–in particular on his concept for an AC motor–Edison rejected the idea. Not only wasn’t Edison interested in motors, he refused to have anything to do with the rival current.

So for the time being Tesla threw himself into work on DC. He told Edison he thought he could substantially improve the DC dynamo. Edison told him if he could, it would earn him a $50,000 bonus. This would have enabled Tesla to set up a laboratory of his own where he could have pursued his AC interests. By dint of extremely long hours and diligent effort, he came up with a set of some 24 designs for new equipment, which would eventually be used to replace Edison’s present equipment.

But he never found the promised $50,000 in his pay envelope. When he asked Edison about this matter, Edison told him he had been joking. “You don’t understand American humor,” he said. Deeply disappointed, Tesla quit his position with the Edison company, and with financial backers, started his own company, which enabled him to work on his AC ideas, among other obligations.

The motor Tesla patented in 1888 is known as the induction motor. It not only provided a serviceable motor for AC, but the induction motor had a distinct advantage over the DC motor. (About two-thirds of the motors in use today are induction motors.)

The idea of the induction motor is simplicity itself, based on the Faraday principle. And its simplicity is its advantage over the DC motor.

An electrical motor–whether DC or AC–is a generator in reverse. The generator operates by causing a conductor (armature) to move (rotate) in a magnetic field, producing a current in the armature. The motor operates by causing a current to flow in an armature in a magnetic field, producing rotation of the armature. A generator uses motion to produce electricity. A motor uses electricity to produce motion.

The DC motor uses commutators and brushes (a contact switching mechanism that opens and closes circuits) to change the direction of the current in the rotating armature, and thus sustain the direction of rotation and direction of current.

In the AC induction motor, the current supply to the armature is by induction from the magnetic field produced by the field current. The induction motor thus does away with the troublesome commutators and brushes (or any other contact switching mechanism). However, in the induction motor the armature wouldn’t turn except as a result of rotation of the magnetic field, which is achieved through the use of polyphase current. The different current phases function in tandem (analogous to pedals on a bicycle) to create differently oriented magnetic fields to propel the armature.

Westinghouse bought up the patents on the Tesla motors almost immediately and set to work trying to adapt them to the single-phase system then in use. This didn’t work. So he started developing a two-phase system. But in December 1890, because of the company’s financial straits–the company had incurred large liabilities through the purchase of a number of smaller companies, and had to temporarily cut back on research and development projects–Westinghouse stopped the work on polyphase. (8)

4) The Modern Centralized Electric Power System

After the innovative technologies which allowed expansion and growth within metropolitan centers were developed there was a race to establish large power plants and distribution systems from power sources to users. Alternating Current aka AC power was found to the preferred method of power transmission over copper wires from distant sources. Direct Current power transmission proved problematic over distances, generated resistance heat resulting in line power losses. (9)

Figure 5: New York City streets in 1890. Besides telegraph lines, multiple electric lines were required for each class of device requiring different voltages (11)

AC has a major advantage in that it is possible to transmit AC power as high voltage and convert it to low voltage to serve individual users.

From the late 1800s onward, a patchwork of AC and DC grids cropped up across the country, in direct competition with one another. Small systems were consolidated throughout the early 1900s, and local and state governments began cobbling together regulations and regulatory groups. However, even with regulations, some businessmen found ways to create elaborate and powerful monopolies. Public outrage at the subsequent costs came to a head during the Great Depression and sparked Federal regulations, as well as projects to provide electricity to rural areas, through the Tennessee Valley Authority and others.

By the 1930s regulated electric utilities became well-established, providing all three major aspects of electricity, the power plants, transmission lines, and distribution. This type of electricity system, a regulated monopoly, is called a vertically-integrated utility. Bigger transmission lines and more remote power plants were built, and transmission systems became significantly larger, crossing many miles of land and even state lines.

As electricity became more widespread, larger plants were constructed to provide more electricity, and bigger transmission lines were used to transmit electricity from farther away. In 1978 the Public Utilities Regulatory Policies Act was passed, making it possible for power plants owned by non-utilities to sell electricity too, opening the door to privatization.

By the 1990s, the Federal government was completely in support of opening access to the electricity grid to everyone, not only the vertically-integrated utilities. The vertically-integrated utilities didn’t want competition and found ways to prevent outsiders from using their transmission lines, so the government stepped in and created rules to force open access to the lines, and set the stage for Independent System Operators, not-for-profit entities that managed the transmission of electricity in different regions.

Today’s electricity grid – actually three separate grids – is extraordinarily complex as a result. From the very beginning of electricity in America, systems were varied and regionally-adapted, and it is no different today. Some states have their own independent electricity grid operators, like California and Texas. Other states are part of regional operators, like the Midwest Independent System Operator or the New England Independent System Operator. Not all regions use a system operator, and there are still municipalities that provide all aspects of electricity. (10)

Figure 6: Diagram of a modern electric power system (11)

A Brief History of Electrical Transmission Development

The first transmission of three-phase alternating current using high voltage took place in 1891 during the international electricity exhibition in Frankfurt. A 15,000 V transmission line, approximately 175 km long, connected Lauffen on the Neckar and Frankfurt.^[6]^[12]

Voltages used for electric power transmission increased throughout the 20th century. By 1914, fifty-five transmission systems each operating at more than 70,000 V were in service. The highest voltage then used was 150,000 V.^[13] By allowing multiple generating plants to be interconnected over a wide area, electricity production cost was reduced. The most efficient available plants could be used to supply the varying loads during the day. Reliability was improved and capital investment cost was reduced, since stand-by generating capacity could be shared over many more customers and a wider geographic area. Remote and low-cost sources of energy, such as hydroelectric power or mine-mouth coal, could be exploited to lower energy production cost.^[3]^[6]

The rapid industrialization in the 20th century made electrical transmission lines and grids a critical infrastructure item in most industrialized nations. The interconnection of local generation plants and small distribution networks was greatly spurred by the requirements of World War I, with large electrical generating plants built by governments to provide power to munitions factories. Later these generating plants were connected to supply civil loads through long-distance transmission. (11)

To be continued in Part 2: Distributed Generation and The Microgrid Revolution

References:

The Forgotten Story Of NYC’s First Power Grid by Kelsey Campbell-Dollaghan
The Electrical Grid – Wikipedia
The History of the Elevator – Wikipedia
Elevator History – Columbia Elevator
The History of Elevators and Escalators – The Wonder Book Of Knowledge | by Henry Chase (1921)
The World’s First Hydroelectric Power Station
Tesla Memorial Society of New York Website
The Day They Turned The Falls On: The Invention Of The Universal Electrical Power System by Jack Foran
How electricity grew up? A brief history of the electrical grid
The electricity grid: A history
Electric power transmission

Aluminum Metal Advancements in Sustainability

Posted on December 16, 2016 by duanetilden

Can the idea of sustainability be determined by metrics? The answer is “Of course”, as any type of improvement can be measured. We understand it is far more efficient to recycle aluminum than it is to produce it the first time, which we call this value embodied energy. However, since refining represents a significant proportion of manufactured costs there becomes a premium on recycling used aluminum. Not only are the savings in energy, they are also in emissions of GHG’s.

Novelis reports.

“Recycling aluminum produces 95 percent fewer greenhouse gas (GHG) emissions and requires 95 percent less energy than primary aluminum production, enabling Novelis to achieve lower GHG emissions despite increasing global production capacity.” (1)

Novelis also reports improvements in Energy Intensity and Water Intensity metrics.

Significant gains were also made in fiscal 2016 as it relates to water and energy intensity. Novelis achieved a 22 percent reduction in water intensity and a 24 percent reduction in energy intensity for the 2007-2009 baseline. (1)

Novelis Core Business

Novelis produces close to 20 percent of the world’s rolled aluminum products and we are strategically located on the four continents where aluminum demand is the greatest: North America, South America, Europe and Asia. Our dedication, innovation and leadership have made us the number one producer of rolled aluminum in Europe and South America, and the number two producer in North America and Asia. We also are the world’s largest recycler of used beverage cans, which comprise a critical input to our operations. Quite simply, recycling is a core element of our manufacturing process. (2)

Figure 1: Novelis Opens World’s Largest Aluminium Recycling Facility (3)

Novelis has officially opened the “world’s largest” aluminium recycling centre located adjacent to the company’s rolling mill in Nachterstedt, Germany and costing over £155m.

The recycling centre will process up to 400,000 metric tons of aluminium scrap annually, turning it back into high-value aluminium ingots to feed the company’s European manufacturing network.

“The Nachterstedt Recycling Centre is a significant step toward our goal to be the world’s low-carbon aluminium sheet producer, shifting our business model from a traditional linear approach to an increasingly closed-loop model,” said Phil Martens, president and chief executive officer of Novelis. (3)

References:

(1) http://www.prnewswire.com/news-releases/novelis-reports-significant-gains-in-sustainability-300379847.html

(2) http://novelis.com/about-us/assets-and-capabilities/

(3) http://www.ciwm-journal.co.uk/novelis-opens-worlds-largest-aluminium-recycling-facility/

Embodied Energy https://duanetilden.com/2014/12/10/embodied-energy-a-measure-of-sustainability-in-buildings-construction/

Energy Efficiency https://duanetilden.com/2016/06/19/measuring-and-monitoring-energy-efficiency/

Aluminum, a Quantum Leap in Renewable Energy Storage

Posted on November 20, 2016 by duanetilden

The future for the metal aluminum has never looked better, for the great investment it represents as a multi-faceted energy efficiency lending material, electrical energy storage medium (battery), and for the advancement of renewable energy sources. These are spectacular claims, and yet in 1855 aluminum was so scarce it sold for about 1200 $/Kg (1) until metallurgists Hall & Heroult invented the modern smelting process over 100 years ago (2).

Image result for aluminum electrolysis

Figure 1. Schematic of Hall Heroult Aluminum Reduction Cell (3)

Aluminum is an energy intensive production process. High temperatures are required to melt aluminum to the molten state. Carbon electrodes are used to melt an alchemical mixture of alumina with molten cryolite, a naturally occurring mineral. The cryolite acts as an electrolyte to the carbon anode and cathodes. Alumina (Al2O3) also known as aluminum oxide or Bauxite is fed into the cell and dissolved into the cryolite, over-voltages reduce the Al2O3 into molten aluminum which pools at the bottom of the cell and is tapped out for further refining.

Aluminum Smelting Process as a Battery

The smelting of Aluminum is a reversible electrolytic reaction, and with modifications to current plant design it is possible to convert the process to provide energy storage which can be tapped and supplied to the electrical grid when required. According to the research the biggest challenge to this conversion process is to maintain heat balances of the pots when discharging energy to prevent freeze-up of the cells. Trimet Aluminum has overcome this problem by incorporating shell heat-exchange technology to the sides of the cell to maintain operating temperatures. Trial runs with this technology have been positive where plans are to push the technology to +/- 25% energy input/output. If this technology is applied to all 3 Trimet plants in Germany, it is claimed that up to 7700 MWh of electrical storage is possible (4).

Trimet Aluminum SE, Germany’s largest producer of the metal, is experimenting with using vast pools of molten aluminum as virtual batteries. The company is turning aluminum oxide into aluminum by way of electrolysis in a chemical process that uses an electric current to separate the aluminum from oxygen. The negative and positive electrodes, in combination with the liquid metal that settles at the bottom of the tank and the oxygen above, form an enormous battery.

By controlling the rate of electrolysis, Trimet has been able to experiment with both electricity consumption and storage. By slowing down the electrolysis process, the plant is able to adjust its energy consumption up and down by roughly 25 percent. This allows the plant to store power from the grid when energy is cheap and abundant and resell power when demand is high and supply is scarce. (5)

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Figure 2. TRIMET Aluminium SE Hamburg with emission control technology (6)

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Figure 3. Rio Tinto Alcan inaugurates new AP60 aluminum smelter in Quebec (7)

Aluminum as a Material and it’s Energy Efficiency Properties

Aluminum and it’s alloys generally have high strength-to-weight ratio’s and are often specified in the aircraft industry where weight reduction is critical. A plane made of steel would require more energy to fly, as the metal is heavier for a given strength. For marine vessels, an aluminum hull structure, built to the same standards, weighs roughly 35% to 45% less than the same hull in steel (8). Weight reduction directly converts to energy savings as more energy would be required to propel the aircraft.

Other modes of transportation, including automobiles, trucking, and rail transport may similarly also benefit from being constructed of lighter materials, such as aluminum. Indeed this would continue the long-standing trend of weight reduction in the design of vehicles. The recent emergence of electric vehicles (EV’s) have required weight reduction to offset the high weight of batteries which are necessary for their operations. The weight reduction translates into longer range and better handling.

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Figure 4. Tesla Model S (9)

In the 1960s, aluminium was used in the niche market for cog railways. Then, in the 1980s, aluminium emerged as the metal of choice for suburban transportation and high-speed trains, which benefited from lower running costs and improved acceleration. In 1996, the TGV Duplex train was introduced, combining the concept of high speed with that of optimal capacity, transporting 40% more passengers while weighing 12% less than the single deck version, all thanks to its aluminium structure.

Today, aluminium metros and trams operate in many countries. Canada’s LRC, France’s TGV Duplex trains and Japan’s Hikari Rail Star, the newest version of the Shinkansen Bullet train, all utilize large amounts of aluminium. (10)

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Figure 5. Image of Japanese Bullet Train (11)

Aluminum For Renewable Energy

One of the biggest criticisms against renewable technologies, such as solar and wind has been that they are intermittent, and not always available when demand demand for energy is high. Even in traditional grid type fossil fuel plants it has been necessary to operate “peaker plants” which provide energy during peak times and seasons.

In California, recent technological breakthroughs in battery technology have been seen as a means of providing storage options to replace power plants for peak operation. However, there remains skepticism that battery solutions will be able to provide the necessary storage capacity needed during these times (12). The aluminum smelter as an energy provider during these high demand times may be the optimum solution needed in a new age renewables economy.

The EnPot technology has the potential to make the aluminium smelting industry not only more competitive, but also more responsive to the wider community and environment around it, especially as nations try to increase the percentage of power generated from renewable sources.

The flexibility EnPot offers smelter operators can allow the aluminium industry to be part of the solution of accommodating increased intermittency. (13)

References:

(1) http://www.aluminum-production.com/aluminum_history.html

(2) http://www.aluminum-production.com/Basic_functioning.html

(3) http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532000000300008

(4) The ‘Virtual Battery‘ – Operating an Aluminium Smelter with Flexible Energy Input. https://energiapotior.squarespace.com/s/Enpot-Trimet-LightMetals2016.pdf

(5) http://www.metalsproclimate.com/metals-pro-climate/best-practice/reduction-of-pfc-process-emissions

(6) http://www.sauder.ubc.ca/Faculty/Research_Centres/Centre_for_Social_Innovation_and_Impact_Investing/Programs/Clean_Capital/Clean_Capital_News_Archive_2014/Aluminum_smelters_could_act_as_enormous_batteries

(7) http://www.canadianmetalworking.com/2014/01/rio-tinto-alcan-inaugurates-new-ap60-aluminum-smelter-in-quebec/

(8) http://www.kastenmarine.com/alumVSsteel.htm

(9) http://www.greencarreports.com/news/1077672_2012-tesla-model-s-is-aluminum-its-secret-weapon

(10) http://transport.world-aluminium.org/en/modes/trainssubways.html

(11) http://www.aluminiumleader.com/focus/aluminium_carriages_help_provide_high_speed_rail_service/

(12) http://www.bloomberg.com/news/articles/2015-12-22/batteries-gaining-favor-over-gas-peaker-plants-in-california

(13) http://www.energiapotior.com/the-virtual-battery

Transitioning Oil & Gas Wells to Renewable Geothermal Energy

Posted on November 11, 2016 by duanetilden

Figure 1: Turbine Generator – Organic Rankine Cycle – ORC Turbine (1)

Existing oil and gas wells offer access to untapped sources of heat which can be converted to electricity or used for other energy intensive purposes. This includes many abandoned wells, which can be reactivated as power sources. These wells, in many cases “stranded assets” have been drilled, explored, and have roads built for access. This makes re-utilization of existing infrastructure cost-effective while minimizing harm to the environment associated with exploration.

In a recently published article in Alberta Oil, an oil & gas industry magazine they point out many of the benefits of converting existing and abandoned wells to geothermal energy.

A recent Continental Resources-University of North Dakota project in the Williston Basin is producing 250 kW of power from two water source wells. The units fit into two shipping containers, and costs US$250,000. This type of micro-generation is prospective in Alberta, and a handful of areas also have potential for multi-MW baseload power production.
In addition to producing power, we can use heat for farming, greenhouses, pasteurization, vegetable drying, brewing and curing engineered hardwood. Imagine what Alberta’s famously innovative farmers and landowners would accomplish if they were given the option to use heat produced from old wells on their properties. Northern communities, where a great many oil and gas wells are drilled nearby, can perhaps reap the most benefits of all. Geothermal can reduce reliance on diesel fuel, and provide food security via wellhead-sourced, geothermally heated, local greenhouse produce. (2)

Water can be recirculated by pumps to extract heat from the earth, and through heat exchangers be used as a source of energy for various forms of machines designed to convert low grade waste heat into electricity. The Stirling Cycle engine is one such mechanical device which can be operated with low grade heat. However recent developments in the Organic Rankine Cycle (ORC) engine seem to hold the greatest promise for conversion of heat to electricity in these installations.

In a “boom or bust” industry subject to the cycles of supply and demand coupling a new source of renewable energy to resource extraction makes sense on many fronts. It could be an economic stimulus not only to the province of Alberta, but throughout the world where oil and gas infrastructure exists, offering new jobs and alternative local power sources readily available.

References:

(1) https://revolution-green.com/new-extra-low-temperature-waste-heat-recovery-system/

(2) http://www.albertaoilmagazine.com/2016/10/geothermal-industry-wants-abandoned-wells/

Related Blog Posts:

Thermoelectric Materials: Converting Heat to Electricity

Posted on August 11, 2016 by duanetilden

When we think of using electricity one of the prevalent uses is to provide a heat source. We see this in our everyday lives as ranges and ovens, microwaves, kettles, hot water tanks, baseboard heaters, as well as other applications. So how about reversing the process and capturing heat and directly converting to electricity, is this possible? As it happens there is a classification of materials which have a property called a thermoelectric effect.

Boosting energy efficiency is an important element of the transition to a sustainable energy system. There are big savings to be made. For example, less than half the energy content of diesel is actually used to power a diesel truck. The rest is lost, mostly in the form of heat. Many industrial processes also deal with the problem of excessive waste heat.

That’s why many research teams are working to develop thermoelectric materials – materials that can convert waste heat into energy. But it’s no easy task. To efficiently convert heat to electricity, the materials need to be good at conducting electricity, but at the same time poor at conducting heat. For many materials, that’s a contradiction in terms.

“One particular challenge is creating thermoelectric materials that are so stable that they work well at high temperatures,” says Anders Palmqvist, professor of materials chemistry, who is conducting research on thermoelectric materials. (1)

Image 1: The enlarged illustration (in the circle) shows a 2D electron gas on the surface of a zinc oxide semiconductor. When exposed to a temperature difference, the 2D region exhibits a significantly higher thermoelectric performance compared to that of bulk zinc oxide. The bottom figure shows that the electronic density of states distribution is quantized for 2D and continuous for 3D materials. Credit: Shimizu et al. ©2016 PNAS

The thermoelectric effect is not as efficient as converting electricity to heat, which is generally 100% efficient. However, with waste energy streams even a small conversion rate may return a significant flow of usable electricity which would normally go up a stack or out a tailpipe.

The large amount of waste heat produced by power plants and automobile engines can be converted into electricity due to the thermoelectric effect, a physics effect that converts temperature differences into electrical energy. Now in a new study, researchers have confirmed theoretical predictions that two-dimensional (2D) materials—those that are as thin as a single nanometer—exhibit a significantly higher thermoelectric effect than three-dimensional (3D) materials, which are typically used for these applications.

The study, which is published in a recent issue of the Proceedings of the National Academy of Sciences by Sunao Shimizu et al., could provide a way to improve the recycling of waste heat into useful energy.

Previous research has predicted that 2D materials should have better thermoelectric properties than 3D materials because the electrons in 2D materials are more tightly confined in a much smaller space. This confinement effect changes the way that the electrons can arrange themselves. In 3D materials, this arrangement (called the density of states distribution) is continuous, but in 2D materials, this distribution becomes quantized—only certain values are allowed. At certain densities, the quantization means that less energy is required to move electrons around, which in turn increases the efficiency with which the material can convert heat into electrical energy. (2)

References:

Minimum Efficiency Standards for Electric Motors to Increase – DOE

Posted on February 1, 2015 by duanetilden

DOE’s analyses estimate lifetime savings for electric motors purchased over the 30-year period that begins in the year of compliance with new and amended standards (2016-45) to be 7.0 quadrillion British thermal units (Btu). The annualized energy savings—0.23 quadrillion Btu—is equivalent to 1% of total U.S. industrial primary electricity consumption in 2013.

Source: www.eia.gov

>” Nearly half of the electricity consumed in the manufacturing sector is used for powering motors, such as for fans, pumps, conveyors, and compressors. About two thirds of this machine-drive consumption occurs in the bulk chemicals, food, petroleum and coal products, primary metals, and paper industries. For more than three decades the efficiency of new motors has been regulated by federal law. Beginning in mid-2016, an updated standard established this year by the U.S. Department of Energy (DOE) for electric motors will once again increase the minimum efficiency of new motors.

The updated electric motor standards apply the standards currently in place to a wider scope of electric motors, generating significant estimated energy savings. […]

Legislation has increased the federal minimum motor efficiencies requirements over the past two decades, covering motors both manufactured and imported for sale in the United States. The Energy Policy Act of 1992 (EPAct) set minimum efficiency levels for all motors up to 200 horsepower (hp) purchased after October 1997. The U.S. Energy Independence and Security Act (EISA) of 2007 updated the EPAct standards starting December 2010, including 201-500 hp motors. EISA assigns minimum, nominal, full-load efficiency ratings according to motor subtype and size. The Energy Policy and Conservation Act of 1975 also requires DOE to establish the most stringent standards that are both technologically feasible and economically justifiable, and to periodically update these standards as technology and economics evolve.

Motors typically fail every 5 to 15 years, depending on the size of the motor. When they fail they can either be replaced or repaired (rewound). When motors are rewound, their efficiencies typically diminish by a small amount. Large motors tend to be more efficient than small motors, and they tend to be used for more hours during the year. MotorMaster+ and MotorMaster+ International, distributed by the U.S. Department of Energy and developed by the Washington State University Cooperative Extension Energy Program in conjunction with the Bonneville Power Administration, are sources for cost and performance data on replacing and rewinding motors.

Improving the efficiency of motor systems, rather than just improving the efficiency of individual motors, may hold greater potential for savings in machine-drive electricity consumption. Analysis from the U.S. Department of Energy shows that more than 70% of the total potential motor system energy savings is estimated to be available through system improvements by reducing system load requirements, reducing or controlling motor speed, matching component sizes to the load, upgrading component efficiency, implementing better maintenance practices, and downsizing the motor when possible.”<

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Continuous Monitoring Solution Designed for Facility and Energy Management

Posted on January 19, 2015 by duanetilden

Verisae and Ecova partner to combine technology and service across nearly 3,000 facilities for an innovative and smart operational approach …

image source: http://energymanagementsystems.org/faqs-on-developing-energy-management-systems/

Source: www.virtual-strategy.com

>” Verisae, a leading global provider of SaaS solutions that drive cost reductions in maintenance, energy, mobile workforces, and environmental management, and Ecova, a total energy and sustainability management company, are pleased to announce the success of their growing partnership to help multisite companies solve their toughest energy, operations, and maintenance challenges.

The continuous monitoring solution combines Verisae’s Software-as-a-Service (SaaS) technology platform with Ecova’s Operations Control Center (OCC) to empower data-driven decision making. The solution analyses operational data in real-time, and has the capability to look for issues and anomalies to predict equipment failure and automatically identify inefficiencies causing higher energy consumption.

Ecova’s fully-staffed 24/7/365 OCC investigates inbound service calls, alarms, telemetry data, and work orders to determine the source of energy, equipment, and system faults and, where possible, corrects issues remotely before they escalate into financial, operational, or comfort problems. Trouble tickets and inbound calls are captured and tracked in the Verisae platform to provide companies with visibility into any operational issues. Combining data analytics that flag potentially troubling conditions with a service that investigates and resolves issues increases operational efficiencies and improves energy savings.

“Companies are constantly challenged to cut costs while maintaining quality, performance, and comfort,” says Jerry Dolinsky, CEO of Verisae. “Our combined solution helps clients address these challenges so they can reduce costs and improve operational efficiencies without impacting value.”

[…] “<

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The Ripple Effect of Energy Efficiency Investment

Posted on January 8, 2015 by duanetilden

“The term “multiple benefits” has emerged to describe the additional value that emerges with any energy performance improvement. The benefits that occur onsite can be especially meaningful to manufacturing, commercial, and institutional facilities. Energy efficiency’s positive ripple effects include increased productivity and product quality, system reliability, and more. ”

Source: aceee.org

>” […] Over the past few decades, researchers have documented numerous cases of energy efficiency improvements—almost always focusing exclusively on energy savings. Non-energy benefits are often recognized, but only in concept. ACEEE’s new report, Multiple Benefits of Business-Sector Energy Efficiency, summarizes what we know about the multiple benefits for the business sector. True quantification of these benefits remains elusive due to a lack of standard definitions, measurements, and documentation, but also in part because variations in business facility design and function ensures that a comprehensive list of potential energy efficiency measures is long, varied, and often unique to the facility.

To give some concrete examples of non-energy benefits at work: Optimizing the use of steam in a plywood manufacturing plant not only reduces the boiler’s natural gas consumption, it also improves the rate of throughput, thus increasing the plant’s daily product yield. A lighting retrofit reduces electricity consumption while also introducing lamps with a longer operating life, thus reducing the labor costs associated with replacing lighting. In many instances, monitoring energy use also provides insights into water or raw material usage, thereby revealing opportunities to optimize manufacturing inputs and eliminate production waste. By implementing energy efficiency, businesses can also boost their productivity. This additional value may make the difference in a business leader’s decision to pursue certain capital investment for their facility.

Meanwhile, energy resource planners at utilities and public utility commissions recognize the impact of large-facility energy demands on the cost and reliability of generation and transmission assets. By maximizing consumer efficiency, costs are reduced or offset throughout a utility system. So the ability to quantify the multiple benefits of investing in energy efficiency, if only in general terms, is an appealing prospect for resource planners eager to encourage greater participation in efficiency programs.

Unfortunately, our research shows that this quantification rarely happens, even though the multiple benefits are frequently evident. A number of studies offer measurement methodologies, anticipating the availability of proper data. When these methodologies are employed with limited samples, we see how proper accounting of non-energy benefits dramatically improves the investment performance of energy efficiency improvements—for example, improving payback times by 50% or better. Samples may provide impressive results, but the data remains too shallow to confidently infer the value to come for any single project type implemented in a specific industrial configuration. Developing such metrics will require more data. […]”<

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Commercial ORC Used for Waste Heat Recovery on Industrial Electric Arc Furnace

Posted on December 1, 2014 by duanetilden

Turboden, a group company of Mitsubishi Heavy Industries, has implemented the first ORC-based heat recovery plant on an Electric Arc Furnace (EAF) in the world

Source: www.pennenergy.com

>” […] The heat recovery system was started up on December 2013. It is connected to the off-gas treatment system of the melting electric furnace. The recovered energy reduces net power consumption, allowing significant CO2 reduction.

In addition to electricity production, the remaining portion of the steam is fed into the Riesa Municipal steam supply system and used in a nearby tire factory production process.

Turboden designs, develops and implements generation plants, allowing reduction of industrial energy consumption and emissions containment through heat recovery from unexploited residual heat streams and exhaust gases in production processes and power plants.

This technology is best applied in energy-intensive industries such as glass, cement, aluminum, iron & steel, where production processes typically generate exhaust gases above 250°C.

These new plants not only provide advantages in terms of environmental sustainability, emissions reduction, increased industrial process efficiency and improved business performance, but they also represent opportunities for increased competitiveness.”<

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Category Archives: Industrial & Manufacturing

Energy Efficiency of Power Production: How Supercritical Carbon Dioxide Turbines Operate

Foreword:

Figure 1. Size comparison of Supercritical Power Turbine to Conventional Steam Turbine (1)

Abstract:

The Principle of Operation

Figure 1. Illustration of a Supercritical CO2 Turbine [Peregrine Turbine Technologies] (2)