What Does Moist Enthalpy Tell Us?

“In terms of assessing trends in globally-averaged surface air temperature as a metric to diagnose the radiative equilibrium of the Earth, the neglect of using moist enthalpy, therefore, necessarily produces an inaccurate metric, since the water vapor content of the surface air will generally have different temporal variability and trends than the air temperature.”

Climate Science: Roger Pielke Sr.

In our blog of July 11, we introduced the concept of moist enthalpy (see also Pielke, R.A. Sr., C. Davey, and J. Morgan, 2004: Assessing “global warming” with surface heat content. Eos, 85, No. 21, 210-211. ). This is an important climate change metric, since it illustrates why surface air temperature alone is inadequate to monitor trends of surface heating and cooling. Heat is measured in units of Joules. Degrees Celsius is an incomplete metric of heat.

Surface air moist enthalpy does capture the proper measure of heat. It is defined as CpT + Lq where Cp is the heat capacity of air at constant pressure, T is air temperature, L is the latent heat of phase change of water vapor, and q is the specific humidity of air. T is what we measure with a thermometer, while q is derived by measuring the wet bulb temperature (or, alternatively, dewpoint…

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Aluminum Metal Advancements in Sustainability

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)


(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/

Related Posts:

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

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)

Related image

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)


(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

Infinity Turbine 2016 ROT IT50

Figure 1:  Radial Outflow 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.


(1)  http://www.infinityturbine.com/

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

Related Blog Posts:

  1. https://duanetilden.com/2016/01/14/alberta-energy-production-and-a-renewable-future/
  2. https://duanetilden.com/2014/12/21/renewable-geothermal-power-with-oil-and-gas-coproduction-technology-may-be-feasible/
  3. https://duanetilden.com/2015/07/25/a-new-era-for-geothermal-energy-in-alberta/
  4. https://duanetilden.com/2015/07/27/oil-well-waste-water-used-to-generate-geothermal-power/
  5. https://duanetilden.com/2013/10/29/supercritical-co2-refines-cogeneration-for-industry/

Low Coal Prices Fuel Demand as Trading Volumes Soar 46%


Image Source:  Power Plant Men

Coal leads surge in European energy exchange trading in first half 2016 -study

Wholesale trading of coal on the exchanges soared 46 percent from a year earlier to 3.5 billion tonnes

FRANKFURT: Coal lead a surge in trading volumes on west European energy exchanges in the first half of this year as traders took advantage of low commodity prices, research company Prospex said on Monday.

Wholesale trading of coal on the exchanges soared 46 percent from a year earlier to 3.5 billion tonnes, according to Prospex.

“Low coal prices mean a fixed amount of trading capital will buy higher volumes than it did in the past,” said Prospex Research director Ben Tait.

“In fact, many traders seeking to hit absolute profit targets have indeed ramped up volumes,” he said.

Prospex’s data covers volumes on what traders call the paper market, where two parties agree deals in the over-the-counter (OTC) market and have them cleared by an exchange.

In coal, this type of business accounts for 98 percent of volumes changing hands in Europe.

Prospex said commodity trading houses remain keen on coal, with some holding extensive physical coal interests that play out on the dominant Amsterdam-Rotterdam-Antwerp (ARA) region of ports that serve Europe’s power stations and steelmakers with raw material.  Read more:  Full Article


Thermoelectric Materials: Converting Heat to Electricity

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 .

That’s why many research teams are working to develop 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 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 . (2)


Related Articles:


  1. http://phys.org/news/2016-06-track-electricity.html#jCp
  2. http://phys.org/news/2016-06-electricity-dimensions.html#jCp

Apple Creates Clean Energy Subsidiary

“Apple has created a subsidiary to sell the excess electricity generated by its hundreds of megawatts of solar projects. The company, called Apple Energy LLC, filed a request with the Federal Energy Regulatory Commission to sell power on wholesale markets across the US.

The company has announced plans for 521 megawatts of solar projects globally. It’s using that clean energy to power all of its data centers, as well as most of its Apple Stores and corporate offices. In addition, it has other investments in hydroelectric, biogas, and geothermal power, and looks to purchase green energy off the grid when it can’t generate its own power. In all, Apple says it generates enough electricity to cover 93 percent of its energy usage worldwide.

But it’s possible that Apple is building power generation capacity that exceeds its needs in anticipation of future growth. In the meantime, selling off the excess helps recoup costs by selling to power companies at wholesale rates, which then gets sold onward to end customers.

It’s unlikely that Apple, which generated more than $233 billion in revenue in fiscal 2015, will turn power generation into a meaningful revenue stream — but it might as well get something out of the investment. The company issued $1.5 billion in green bonds earlier this year to finance its clean energy projects.” (2)

Related Articles:


  1. http://inhabitat.com/apple-is-launching-a-new-company-to-sell-surplus-solar-energy/apple-cupertino-hq-foster-partners-1/
  2. http://www.theverge.com/2016/6/9/11896502/apple-clean-solar-energy-subsidiary-wholesale

The Smart Grid – Modern Electrical Infrastructure

When we talk about the emerging Smart Grid there comes with the topic an array of exciting and new technologies; Micro-Grids, Distributed Generation, Smart Meters, Load Shifting, Demand Response, Electric Vehicles with Battery Storage for Demand Response, and more.  Recent development in Renewable Energy sources has been driven by concerns over Climate Change, allowing for unprecedented growth in residential and commercial PV Solar Panel installations.


Figure 1:  Redwood High School in Larkspur, CA installed a 705kW SunPower system that’s projected to save $250,000 annually. The carports include EV charging stations for four cars. (1)

Climate Change and burning of fossil fuels are hot topics in the world. Most recently the city of San Francisco has mandated the installation of solar panels on all new buildings constructed under 10 storeys, which will come into effect in 2017 as a measure to reduce carbon emissions.  Currently all new buildings in California are required to set aside 15% of roof area for solar. (2)

“Under existing state law, California’s Title 24 Energy Standards require 15% of roof area on new small and mid-sized buildings to be “solar ready,” which means the roof is unshaded by the proposed building itself, and free of obtrusions. This state law applies to all new residential and commercial buildings of 10 floors or less.

Supervisor Wiener’s ordinance builds on this state law by requiring this 15% of “solar ready” roof area to have solar actually installed. This can take the form of either solar photovoltaic or solar water panels, both of which supply 100% renewable energy.” (3)

Weather and Aging Infrastructure:

Despite an increasing abundance of energy-efficient buildings and other measures, electricity demand has risen by around 10% over the last decade, partly driven by the massive growth of digital device usage and the expanding demand for air conditioning, as summers continue to get hotter in many states.

According to 2013 data from the Department of Energy (DOE), US power grid outages have risen by 285% since records on blackouts began in 1984, for the most part driven by the grid’s vulnerability to unusual and extreme weather events – such as the devastating Hurricane Sandy in 2012 that caused extensive power outages across the East Coast – which are becoming less unusual as the years roll on.

“We used to have two to five major weather events per year from the 50s to the 80s,” said University of Minnesota Professor of Electrical and Computer Engineering Massoud Amin in a 2014 interview with the International Business Times.

“Between 2008 and 2012, major outages caused by weather increased to 70 to 130 outages per year. Weather used to account for about 17% to 21% of all root causes. Now, in the last five years, it’s accounting for 68% to 73% of all major outages.” (4)

How is the Smart Grid so different from the traditional electrical grid?

The established model of providing power to consumers involves the supply of electricity generated from a distant source and transmitted at high voltage to sub-stations local to the consumer, refer to Figure 2.  The power plants that generate the electricity are mostly thermo-electric (coal, gas and nuclear power), with some hydro-electric sources (dams and reservoirs) and most recently wind farms and large solar installations.

“The national power grid that keeps America’s lights on is a massive and immensely valuable asset. Built in the decades after the Second World War and valued today at around $876bn, the country’s grid system as a whole connects electricity from thousands of power plants to 150 million customers through more than five million miles of power lines and around 3,300 utility companies.” (4)

power_fig1 Old Grid Model.gif

Figure 2:  Existing Transmission and Distribution Grid Structure within the Power Industry (5)

The (Transmission & Distribution) market supplies equipment, services and production systems for energy markets. The initial stage in the process is converting power from a generation source (coal, nuclear, wind, etc.) into a high voltage electrical format that can be transported using the power grid, either overhead or underground. This “transformation” occurs very close to the source of the power generation.

The second stage occurs when this high-voltage power is “stepped-down” by the use of switching gears and then controlled by using circuit breakers and arresters to protect against surges. This medium voltage electrical power can then be safely distributed to urban or populated areas.

The final stage involves stepping the power down to useable voltage for the commercial or residential customer.  In short, while power generation relates to the installed capacity to produce energy from an organic or natural resource, the T&D space involves the follow up “post-power generation production” as systems and grids are put in place to transport this power to end users. (5)

The Smart Grid is an evolution in multiple technologies which in cases is overlaying or emerging from the existing grid.  New generating facilities such as wind power or solar installations which may be small or local to a municipal or industrial user are being tied into the existing grid infra-structure.  In some cases residential PV Solar systems are being tied into the Grid with some form of agreement to purchase excess energy, in some cases at rates favorable to the installer, depending on the utility and region.

Another characteristic of the evolving Smart Grid is in communication technology and scalability.  Use of wifi protocols for communication between parts of the system allow for new processes and access to resources which were previously unavailable.  Ability to control systems to defer demand to non-peak hours within a building as one example.

Microgrids, smaller autonomous systems servicing a campus of buildings or larger industry,  may plug into a larger City-wide Smart Grid in a modular manner.  In the event of a catastrophic event such as a hurricane or earthquake the Smart Grid offers users resiliency through multiple sources of energy supply.

Distributed Generation includes a number of different and smaller scale energy sources into the mix.  The newer, small scale Renewable Energy projects which are being tied to the electrical grid as well as other technologies such as Co-Generation, Waste To Energy facilities, Landfill Gas Systems, Geothermal and the like.  As growth continues there needs to be ways to control and manage these multiple energy sources into the grid.  Also increased needs to maintain privacy, isolate and control systems, and prevent unauthorized access and control.  This is leading to growth in  Energy Management and Security Systems.


Figure 3:  An artist’s rendering of the massive rail used in the ARES power storage project to store renewable energy as gravitational potential energy. Source: ARES North America (6)

Energy Storage is emerging as necessary in the Smart Grid due to fluctuations in source supply of energy, especially Solar and Wind Power, and the intermittent and cyclical nature of user demand.   The existing grid does not have the need for energy storage systems as energy sources were traditionally large power stations which generally responded to anticipated need during the course of the day.

As more Renewable Energy systems go online the need for storage will grow.  Energy Storage in its various forms will also enable Load Shifting or Peak Shaving strategies for economic gains in user operations.  These strategies are already becoming commercially available for buildings to save the facility operators rate charges by limiting demand during peak periods at higher utility rates.


Figure 4:  Effect of Peak Shaving using Energy Storage  (6) 

Peak-load shifting is the process of mitigating the effects of large energy load blocks during a period of time by advancing or delaying their effects until the power supply system can readily accept additional load. The traditional intent behind this process is to minimize generation capacity requirements by regulating load flow. If the loads themselves cannot be regulated, this must be accomplished by implementing energy storage systems (ESSs) to shift the load profile as seen by the generators (see Figure 4).

Depending on the application, peak-load shifting can be referred to as “peak shaving” or “peak smoothing.” The ESS is charged while the electrical supply system is powering minimal load and the cost of electric usage is reduced, such as at night. It is then discharged to provide additional power during periods of increased loading, while costs for using electricity are increased. This technique can be employed to mitigate utility bills. It also effectively shifts the impact of the load on the system, minimizing the generation capacity required. (6)

Challenges with chemical storage systems such as batteries are scale and cost.  Currently pumped hydro is the predominant method of storing energy from intermittent sources providing 99% of global energy storage. (7)


Figure 5:  Actual Savings accrued due to Demand Response Program  (8) 

Demand Response (DR) is another technology getting traction in the Smart Grid economy. As previously mentioned Energy Management and Security Systems are “…converging with Energy Storage technology to make DR a hot topic.  First, the tools necessary to determine where energy is being stored, where it is needed and when to deliver it is have developed over decades in the telecommunications sector.  Secondly, the more recent rush of advanced battery research is making it possible to store energy and provide the flexibility necessary for demand response to really work. Mix that with the growing ability to generate energy on premises through solar, wind and other methods (Distributed Generation) and a potent new distributed structure is created.” (9)

Demand response programs provide financial incentives to reduce energy consumption during peak periods of energy demand. As utilities and independent system operators (ISOs) are pressured to keep costs down and find ways to get as many miles as they can out of every kilowatt, demand response programs have gained popularity. (8)


Figure 6:  The Demonstration Project 2’s Virtual Power Plant (10) 

Virtual Power Plant: When an increasing share of energy is produced by renewable sources such as solar and wind, electricity production can fluctuate significantly. In the future there will be a need for services which can help balance power systems in excess of what conventional assets will be able to provide. Virtual power plants (VPPs) are one of the most promising new technologies that can deliver the necessary stabilising services.  (11)

In the VPP model an energy aggregator gathers a portfolio of smaller generators and operates them as a unified and flexible resource on the energy market or sells their power as system reserve.

VPPs are designed to maximize asset owners’ profits while also balancing the grid. They can match load fluctuations through forecasting, advance metering and computerized control, and can perform real-time optimization of energy resources.

“Virtual power plants essentially represent an ‘Internet of Energy,’ tapping existing grid networks to tailor electricity supply and demand services for a customer,” said Navigant senior analyst Peter Asmus in a market report. The VPP market will grow from less than US $1 billion per year in 2013 to $3.6 billion per year by 2020, according to Navigant’s research — and one reason is that with more variable renewables on the grid flexibility and demand response are becoming more crucial.  (12)


Figure 7:   Example of a Microgrid System With Loads, Generation, Storage and Coupling to a Utility Grid (13)

Microgrids:  Microgrids are localized grids that can disconnect from the traditional grid to operate autonomously and help mitigate grid disturbances to strengthen grid resilience (14).  The structure of a microgrid is a smaller version of the smart grid formed in a recursive  hierarchy where multiple local microgrids may interconnect to form the larger smart grid which services a region or community.


The convergence of aging existing infrastructure, continued growth in populations and electrical demand and concerns over climate change have lead to the emerging smart grid and it’s array of new technologies.  This trend is expected to continue as new growth and replacement will be necessary for an aging electrical grid system, from the larger scope transmission systems and utilities, to smaller scale microgrids.  These systems will become integrated and modular, almost plug-and-play, with inter-connectivity and control through wireless internet protocols.


  1. https://cleanpowermarketinggroup.com/category/blog/
  2. http://www.npr.org/sections/thetwo-way/2016/04/20/474969107/san-francisco-requires-new-buildings-to-install-solar-panels
  3. https://medium.com/@Scott_Wiener/press-release-board-of-supervisors-unanimously-passes-supervisor-wiener-s-legislation-to-require-693deb9c2369#.3913ug8ph
  4. http://www.power-technology.com/features/featureupgrading-the-us-power-grid-for-the-21st-century-4866973/
  5. http://www.incontext.indiana.edu/2010/july-aug/article3.asp
  6. http://www.csemag.com/single-article/implementing-energy-storage-for-peak-load-shifting/95b3d2a5db6725428142c5a605ac6d89.html
  7. http://www.forbes.com/sites/jamesconca/2016/05/26/batteries-or-train-pumped-energy-for-grid-scale-power-storage/#30b5b497de55
  8. http://www.summitenergygps.com/optimize-rebates-incentives-credits.html
  9. https://duanetilden.com/2015/12/26/demand-response-energy-distribution-a-technological-revolution/
  10. https://hub.globalccsinstitute.com/publications/twenties-project-final-report-short-version/demonstration-project-2-large-scale-virtual-power-plant-integration-derint
  11. http://energy.gov/oe/services/technology-development/smart-grid/role-microgrids-helping-advance-nation-s-energy-system
  12. http://www.renewableenergyworld.com/articles/print/volume-16/issue-5/solar-energy/virtual-power-plants-a-new-model-for-renewables-integration.html
  13. http://w3.usa.siemens.com/smartgrid/us/en/microgrid/pages/microgrids.aspx
  14. http://energy.gov/oe/services/technology-development/smart-grid/role-microgrids-helping-advance-nation-s-energy-system

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Other Related Articles and Websites:

Supercritical CO2 Used For Solar Battery Power System

“GE has announced it is working on a way to use CO2 pollution to make new types of solar batteries that could each power up to 100,000 homes. CO2 is the main contributor to climate change, and is released into the atmosphere when coal is processed at power plants. Currently environmental procedures mean that some CO2 from these plants is captured and stored, so it’s not released back into the atmosphere. But the question has always been: What do you do with the stored gas?” (1)


dodge-sco23 supercritical CO2 turbine

Figure #1:  Comparison of 10 MWe Turbines (2)

What are the Benefits of Supercritical CO2?  With the transition from steam generation to using Supercritical CO2 as a working fluid, we seen large gains in energy efficiency conversion, coupled with significant size (footprint) reduction of turbomachines.  Other benefits include sequestering CO2 from the environment and reducing GHG emissions.   Also, this system can be utilized to capture energy from other heat sources including waste heat streams and co-generation applications. 

Supercritical CO2 image comparison

Figure 2:  Relative size  comparison of steam, helium and supercritical CO2 turbomachinery for Generation IV Nuclear Reactors (3)

What is Supercritical CO2?  “[…] Supercritical CO2 is a fluid state of carbon dioxide where it is held above its critical pressure and critical temperature which causes the gas to go beyond liquid or gas into a phase where it acts as both simultaneously. Many fluids can achieve supercritical states and supercritical steam has been used in power generation for decades. Supercritical CO2 has many unique properties that allow it to dissolve materials like a liquid but also flow like a gas. sCO2 is non-toxic and non-flammable and is used as an environmentally-friendly solvent for decaffeinating coffee and dry-cleaning clothes.

dodge-sco211 supercritical CO2 2

Figure 3:  CO2 phase diagram illustrating supercritical region. (4)

The use of sCO2 in power turbines has been an active area of research for a number of years, and now multiple companies are bringing early stage commercial products to market. The attraction to using sCO2 in turbines is based on its favorable thermal stability compared to steam which allows for much higher power outputs in a much smaller package than comparable steam cycles. CO2 reaches its supercritical state at moderate conditions and has excellent fluid density and stability while being less corrosive than steam.  The challenges in using sCO2 are tied to identifying the best materials that can handle the elevated temperatures and pressures, manufacturing turbo machinery, valves, seals, and of course, costs. […] ”  (2)

How will this work?

“[…] The design has two main parts. The first one collects heat energy from the sun and stores it in a liquid of molten salt. “This is the hot side of the solution,” Sanborn says. The other component uses surplus electricity from the grid to cool a pool of liquid CO2 so that it becomes dry ice.

During power generation, the salt releases the heat to expand the cold CO2 into a supercritical fluid, a state of matter where it no longer has specific liquid and gas phases. It allows engineers to make the system more efficient.

The supercritical fluid will flow into an innovative CO2 turbine called the sunrotor, which is based on a GE steam turbine design. Although the turbine can fit on an office shelf (see image above) it can generate as much as 100 megawatts of “fast electricity” per installed unit—enough to power 100,000 U.S. homes.

Sanborn believes that a large-scale deployment of the design would be able to store “significant amounts” of power —— and deliver it back to the grid when needed. “We’re not talking about three car batteries here,” he says. “The result is a high-efficiency, high-performance renewable energy system that will reduce the use of fossil fuels for power generation.”

He says the system could be easily connected to a solar power system or a typical gas turbine. The tanks and generators could fit on trailers. His goal is to bring the cost to $100 per megawatt-hour, way down from the $250 it costs to produce the same amount in a gas-fired power plant. “It is so cheap because you are not making the energy, you are taking the energy from the sun or the turbine exhaust, storing it and transferring it,” says Sanborn.

The process is also highly efficient, Sanborn says, yielding as much as 68 percent of the stored energy back to the grid. The most efficient gas power plants yield 61 percent. The team is now building a conceptual design, which Sanborn believes could take five to 10 years to get from concept to market. […]” (5)

Read more at:

1.  https://duanetilden.com/2013/10/29/supercritical-co2-refines-cogeneration-for-industry/

2. https://duanetilden.com/2013/10/29/supercritical-co2-turbine-for-power-production-waste-heat-energy-recovery/

3. https://duanetilden.com/2013/10/29/waste-heat-recovery-using-supercritical-co2-turbines-to-create-electrical-power/

4. https://duanetilden.com/2015/04/23/doe-invests-in-super-critical-carbon-dioxide-turbine-research-to-replace-steam-for-electric-power-generators/



  1. http://www.fastcompany.com/3057630/fast-feed/ge-is-working-on-a-way-to-turn-co2-pollution-into-solar-batteries
  2. http://breakingenergy.com/2014/11/24/supercritical-carbon-dioxide-power-cycles-starting-to-hit-the-market/
  3. http://large.stanford.edu/courses/2014/ph241/dunham1/
  4. https://commons.wikimedia.org/wiki/File:Carbon_dioxide_pressure-temperature_phase_diagram.svg
  5. http://www.vanguardngr.com/2016/03/ge-report-this-scientist-has-turned-the-tables-on-greenhouse-gas-using-co2-to-generate-clean-electricity/


Alberta Energy Production And A Renewable Future

Author:  Duane M. Tilden, P.Eng  (January 14th, 2016)

Abstract:  Energy sources and pricing are hot topics world-wide with the Climate Change agenda leading the way.  Last year at the 2015 Paris Climate Conference long-term goal of emissions neutrality was established to be by as soon as 2050.  Alberta currently produces more atmospheric carbon emissions and other pollutants than any other Province in Canada, and in order to meet clean air objectives the energy sectors which consume & mine the natural resources of the Province will have to shift to non-polluting & renewable energy sources and be more efficient in energy utilization.  To achieve these goals new infrastructure will have to be built which will have the likely consequences of raising energy pricing as well as alter consumption rates and patterns.


Transportation is a vital link in modern society, and often a personal vehicle is chosen as the main mode of mobility to work, leisure, & social purposes.  Cars and trucks also provide means of work and commerce & are essential to our way of life.  Most of these vehicles are fueled by gasoline, some by diesel, propane, and more recently the electric vehicle (EV) and hybrids.


GraphData Gas Price Comparison Canada

Graph #1:  Average Cost Comparison of Gasoline in Major Canadian Cities

In Alberta, using Calgary as a basis for comparison, it is apparent that pricing to consumers for gasoline is below nation-wide market averages when measured Province by Province, as demonstrated in Graph #1 (1). While if you live in Vancouver the cost is considerably higher, due to included carbon taxes and a transit levy among additional charges.  Additional means of moving growing populations efficiently have been seen by the development of LRT mass transit for the rapid movement of citizens to work, school, or social events.

Rapidly moving the large segments of the population in a cost effective manner is important to growth.  Buses are an important link in this mix as are cycling routes, green-ways and parks.  Changes in fuels for trucks, buses and trains by converting from diesel fuel to LNG will also provide for reductions in emissions while providing economic opportunity for utilization of the existing plentiful resource.  While EV’s show promise, the battery technologies for energy storage need further development.

Alberta Electricity Production

Alberta still relies on out-dated coal plants to generate electricity.  According to a CBC article coal provides power to 55% of homes in Alberta, and is the second largest contributor to emissions (2) and GHG’s to the Oil Sands projects.  However, it has been noted that the utility is reluctant to decommission recently constructed coal plants, until they have earned back (or are compensated for) their investment in capital costs.


Photo #1:  Highvale coal mine to feed the nearby Sundance power plant (3)  

Photo credit:  John Lucas / Edmonton Journal

There are power purchase agreements in place, which may extend 50 to 60 years from the construction date of the plant (2).  It may be possible that the coal fired power plants could be converted to burn natural gas, which Alberta has in abundance, rather than be decommissioned.  However, this would still require the closure of the coal mines and mining operations currently supplying the existing power plants.  Also, combustion of natural gas will still release GHG’s into the atmosphere, while less than coal, they are not a total elimination of emissions.

Residential Energy Consumption

When comparing monthly residential electrical energy costs across Canada, using data obtained from a survey performed by Manitoba Hydro, we see that Edmonton and Calgary are in the lower middle range of pricing (4).  Variances in all regions will occur based on average home size, building codes and insulation requirements, heating system types and other factors.  Some homes may be heated with electric baseboard which will result in a higher electric bill while other homes may be heated using natural gas as a fuel.  Also household hot water generation can be by electric or gas-fired heater, so consumption of natural gas must be considered with electrical power usage to get a complete picture of energy consumption.


Charts #1 & 2:  Average Monthly Cost For Residential Electricity in Major Canadian Cities For Equivalent Usage in kWh (4)

Inspecting these charts it is proposed that a price increase of 10 to 20% to Alberta electrical energy consumers by a separate tax or fee to pay for a shift in technology would be reasonable when compared to other Canadian Cities.   Additional tariffs on natural gas consumption would also be recommended.  Such an increase would likely have a secondary benefit of creating an incentive for energy efficiency upgrades by home owners such as increased insulation, better windows and heating system upgrades. Such improvements would in turn lead to reduced demand at the source and thus to lower GHG & particulate emissions to the atmosphere.

Climate and the Proposed Energy Code

Energy consumption in populations is normalized in a number of ways, generally defined by habits and patterns.  We observe that in traffic as volumes increase early in the morning as commuters travel to work, and in the opposite direction as they head home in the evening.  Often people will attempt to “beat the traffic”.  This is an admirable goal in energy usage as well, for consumption of electricity will follow other such predictable patterns as people eat meals, shower, and perform other rituals that interface with electrical,  heating,  ventilating, elevators, water supply and disposal systems that form infrastructure and services provided by municipalities and utilities.

As these systems need to be energized and maintained, it is desirable to be able to predict and control the consumption and distribution of resources.  The greater of these is the electrical generation and distribution system.   Also, emerging technological advancements in energy efficiency such as CFL, LCD displays, computers, refrigeration, energy storage and more.  Advancements in co-generation, district energy systems, and other end use distribution of energy which provide economies of scale are also possible as strategies to obtain goals.Heating Degree Days - Lower Western Canada

Map #1:  Partial Map of Heating Degree Days for South-Western Canada (5)

Opportunities will exist for building mechanical system enhancements and upgrades as they may provide energy savings and cost reductions to users often calculated with a minimum nominal payback period of 5 to 7 years (and should be determined in every case).   The HDD map can provide a source of information which is used in energy models to determine predicted building energy costs when calculating payback periods to justify system upgrades or design decisions.  Obtaining and monitoring building energy consumption rates and year over year changes are important resources in determining where systems are running at below optimal rates and require replacement.

In new building construction the National Energy Code for Buildings 2011 (NECB) (6) has been adopted by Alberta (7) for all municipalities.  As there are higher HDD values attributed to Calgary and Edmonton as seen in the HDD Map of Western Canada, a requirement for stringent construction methods and materials to higher standards ensure new buildings meet carbon emissions reduction goals.


Photo #2:  Construction of Towers in Calgary with High Window to Wall Ratios 

Photo Credit: Duane Tilden P.Eng

Increased requirements in glass U-values and shading coefficients, maximum window to wall ratios (WWR) to reduce undesirable solar heat gain and heat losses, energy consumption and improve occupant comfort.  Buildings with excessive glazing are difficult to heat and cool, requiring sophisticated mechanical systems to offset poor performance by the building envelope.

Code mandated higher insulation values & better materials; moisture and heat control of the envelope through better design.  Higher efficiency requirements for mechanical systems; (fans & ducts, pumps & pipes, and wires & motors), lighting, controls, and other components of the building and it’s envelope.  Energy modeling should be performed of larger significant buildings to optimize operations in the design phase.  Commissioning of the building is integral to ensuring compliance throughout the project to it’s final phases at substantial completion and occupancy.

Renewable Energy

Renewable energy technologies including solar power and wind generation  have been gaining rapid adoption elsewhere in the world, while in Alberta (8) carbon based fuels currently provide over 80% of electrical power generation.   This has not been for a lack of wind and solar resources in Alberta but to be attributed to the large capital investments in fossil fuel resource extraction.  Other renewable technologies such as bio-mass, hydro, and geothermal may also be employed and should be investigated as alternatives to existing thermo-electric power plants.

Alberta Energy Sources - 2015

Table #1:  Installed Electrical Generating Capacity by Fuel Source in Alberta (8)

Currently, Alberta has the third highest installed wind power capacity in Canada behind Ontario and Quebec.  Wind energy not only represents a means to green the power production, it also will contribute jobs and income to the economy.  As one source of electricity and revenues is removed another source will fill the void.


Map #2:  Installed Wind Power Capacity by Province in Canada (9)

While significant inroads have been made in Alberta for wind power which is already established as a major power source for the future, there is unrealized potential for the installation of solar power production.  It has been noted that a photo-voltaic installation in Calgary is 52% more efficient than one installed in Berlin, Germany.  Meanwhile, Germany has 18,000 times more solar power generation capacity than installed in Alberta (10).


Map #4:  Solar Resource Comparison for Alberta & Germany (10)

Alberta has significant solar resources, even during the winter when daylight hours are shorter. Lower temperatures improve PV efficiency, and properly tilted south facing panels optimize light capture, while the flat terrain of the prairies provide unobstructed maximum daylight.  Light reflection by snow on the ground would further enhance light intensity during the colder months.  Thus solar represents a relatively untapped potential source of significant electrical power for Alberta and an unrealized economic opportunity for consumers and industry.



Map #5:  Solar Resource Map for Canada With Hotspots (11)

Energy Efficiency, Smart Grid & Technological Advancements

Renewable energy produces electricity from natural resources without generating carbon and particulate emissions.  Another method of controlling emissions is to reduce the amount of energy consumed by being more efficient with the energy we already produce.   We can achieve this by using higher efficiency equipment, changing consumer patterns of use to non-peak periods, use of Smart Meter’s to monitor consumer usage and to alert homeowners when there is a problem with high consumption which could result in higher bills than normal if the problem remained unreported.

There are other advancements in the electrical grid system which are on the horizon which will enable a utility maximize resources by such means as energy storage, micro-grids, demand response to name a few.  Also, property owners and businesses could be able to grid-tie private solar panel (PV) and storage systems to supplement the utilities electrical system with additional power during the day.


In order to meet the goal of atmospheric emissions neutrality as agreed to at the 2015 Paris Climate Conference Alberta is posed with making decisions on how electricity is to be produced in the future.  Eliminating coal power plants and replacing them with Renewable Energy power sources such as solar and wind power are proven methods to reducing GHG and particulate emissions as these power sources do not involve combustion and discharge of waste gases formed during the combustion process.  Coal combustion is well documented as a major contributor of GHG’s to the atmosphere.

To make the transition will require capital for financing to build new infrastructure.  Funding of these projects should be raised proportionally charged to users with increased rates.  These rate increases will provide further incentives to reducing energy consumption and thus air emissions.  Jobs will shift and employment will be created in new forms as the old is phased out and replaced with new technology.  These new systems will have to be designed, built and maintained while the workforce will require training in new methods.  There will be many new opportunities for growth and advancement resulting from the implementation of these changes to meet Canada’s International commitments.


  1. http://www.nrcan.gc.ca/energy/fuel-prices/4593
  2. http://www.cbc.ca/news/business/coal-compensation-power-alberta-1.3321467
  3. http://edmontonjournal.com/business/local-business/albertas-commitment-to-phase-out-coal-fired-power-sparks-fears-of-job-losses
  4. https://www.hydro.mb.ca/regulatory_affairs/energy_rates/electricity/utility_rate_comp.shtml
  5. http://ftp2.cits.rncan.gc.ca/pub/geott/atlas/archives/english/5thedition/environment/climate/mcr4033.jpg
  6. http://www.nrc-cnrc.gc.ca/eng/publications/codes_centre/necb_2011_adaptation_guidelines.html
  7. http://www.municipalaffairs.alberta.ca/CP_Energy_Codes_Information
  8. http://www.energy.alberta.ca/electricity/682.asp
  9. http://canwea.ca/wind-energy/installed-capacity/
  10. http://www.greenenergyfutures.ca/blog/sunny-days-ahead-solar-alberta
  11. http://pv.nrcan.gc.ca/index.php?lang=e&m=r