An Engineer’s Take On Major Climate Change

1. Climate science is very complicated and very far from being settled.

2. Earth’s climate is overwhelmingly dominated by negative-feedbacks that are currently poorly represented in our Modeling efforts and not sufficiently part of ongoing investigations.

3. Climate warming drives atmospheric CO2 upward as it stimulates all natural sources of CO2 emission. Climate cooling drives atmospheric CO2 downward.

4. Massive yet delayed thermal modulations to the dissolved CO2 content of the oceans is what ultimately drives and dominates the modulations to atmospheric CO2.

5. The current spike in atmospheric CO2 is largely natural (~98%). i.e. Of the 100ppm increase we have seen recently (going from 280 to 380ppm), the move from 280 to 378ppm is natural while the last bit from 378 to 380ppm is rightfully anthropogenic.

6. The current spike in atmospheric CO2 would most likely be larger than now observed if human beings had never evolved. The additional CO2 contribution from insects and microbes (and mammalia for that matter) would most likely have produced a greater current spike in atmospheric CO2.

7. Atmospheric CO2 has a tertiary to non-existent impact on the instigation and amplification of climate change. CO2 is not pivotal. Modulations to atmospheric CO2 are the effect of climate change and not the cause.

Watts Up With That?

Guest essay by Ronald D. Voisin

Let’s examine, at a high and salient level, the positive-feedback Anthropogenic Global Warming, Green-House-Gas Heating Effect (AGW-GHGHE) with its supposed pivotal role for CO2. The thinking is that a small increase in atmospheric CO2 will trigger a large increase in atmospheric Green-House-Gas water vapor. And then the combination of these two enhanced atmospheric constituents will lead to run-away, or at least appreciable and unprecedented – often characterized as catastrophic – global warming.

This theory relies entirely on a powerful positive-feedback and overriding (pivotal) role for CO2. It further assumes that rising atmospheric CO2 is largely or even entirely anthropogenic. Both of these points are individually and fundamentally required at the basis of alarm. Yet neither of them is in evidence whatsoever. And neither of them is even remotely true. CO2 is not only “not pivotal” but it…

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Water Conservation and a Change in Climate Ends California Drought

Water scarcity is becoming a greater problem in our world as human demands for water increases due to population growth, industry, agriculture, and energy production. When the water supply is being pushed beyond its natural limits disaster may occur.  For California residents the end of the drought is good news.  Return of wet weather raises reservoir levels and effectively prevents wildfires.  However, another drought could be around the corner in years to come.  Thus government and water users need to remain vigilant and continue to seek ways to conserve and reduce water use.
ca-reservoirs 2017 End of drought.png
Figure 1. 2017 California Major Water Reservoir Levels
By Bark Gomez and Yasemin Saplakoglu, Bay Area News Group (1)
Friday, April 07, 2017 05:17PM

Gov. Jerry Brown declared an end to California’s historic drought Friday, lifting emergency orders that had forced residents to stop running sprinklers as often and encouraged them to rip out thirsty lawns during the state’s driest four-year period on record.

The drought strained native fish that migrate up rivers and forced farmers in the nation’s leading agricultural state to rely heavily on groundwater, with some tearing out orchards. It also dried up wells, forcing hundreds of families in rural areas to drink bottled water and bathe from buckets.

Brown declared the drought emergency in 2014, and officials later ordered mandatory conservation for the first time in state history. Regulators last year relaxed the rules after a rainfall was close to normal.

But monster storms this winter erased nearly all signs of drought, blanketing the Sierra Nevada with deep snow, California’s key water source, and boosting reservoirs.

“This drought emergency is over, but the next drought could be around the corner,” Brown said in a statement. “Conservation must remain a way of life.” (2)



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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The End of Oil Domination? – German Government Votes to Ban Sales of ICE Vehicles by 2030


Figure 1:  Chart showing recent drop in Diesel Car sales, AID Newsletter


“[…] Germany’s Bundesrat has passed a resolution to ban the internal combustion engine starting in 2030,Germany’s Spiegel Magazin writes. Higher taxes may hasten the ICE’s departure.

An across-the-aisle Bundesrat resolution calls on the EU Commission in Brussels to pass directives assuring that “latest in 2030, only zero-emission passenger vehicles will be approved” for use on EU roads. Germany’s Bundesrat is a legislative body representing the sixteen states of Germany. On its own, the resolution has no legislative effect. EU type approval is regulated on the EU level. However, German regulations traditionally have shaped EU and UNECE regulations.

EU automakers will be alarmed that the resolution, as quoted by der Spiegel, calls on the EU Commission to “review the current practices of taxation and dues with regard to a stimulation of emission-free mobility.”

  • “Stimulation of emission-free mobility” can mean incentives to buy EVs. Lavish subsidies doled out by EU states have barely moved the needle so far.
  • A “review the current practices of taxation and dues” is an unambiguously broad hint to end the tax advantages enjoyed by diesel in many EU member states. The lower price of diesel fuel, paired with its higher mileage per liter, are the reason that half of the cars on Europe’s roads are diesel-driven. Higher taxes would fuel diesel’s demise. […]

With diesel already on its tipping point in Europe, higher taxes and increased prices at the pump would be the beginning of the fuel’s end. As evidenced at the Paris auto show, the EU auto industry seems to be ready to switch to electric power, and politicians just signaled their willingness to force the switch to zero-emission, if necessary. Environmentalists undoubtedly will applaud this move, and the sooner diesel is stopped from poisoning our lungs with cancer-causing nitrous oxide, the better. Cult-like supporters of electric carmaker Tesla will register the developments with trepidation.

When EU carmakers are forced by law to produce the 13+ million electric cars the region would need per year, the upstart carmaker would lose its USP, and end up as roadkill. Maybe even earlier. Prompted by a recent accident on a German Autobahn, experts of Germany’s transport ministry declared Tesla’s autopilot a “considerable traffic hazard,” Der Spiegel wrote yesterday.Transport Minister Dobrindt so far stands between removing Germany’s 3,000 Tesla cars from the road, the magazine writes. Actually, until the report surfaced, the minister’s plan was to subsidize Autopilot research in Germany’s inner cities. “Let’s hope no Tesla accident happens,” the minister’s bureaucrats told Der Spiegel. It happened, but no-one died.”

Via Forbes:


Shipping’s Growing Carbon Gap

Transport's Carbon & Energy Future


On the face of it, Shipping is the most efficient of freight transport modes. Intermodal shipping containers kick-started rapid growth in trade globalisation 60 years ago, and container ships, tankers and bulk carriers have been getting bigger ever since. Carrying more freight with less fuel on a tonne-mile basis, shipping has the highest energy productivity of all transport modes.

Yet looks can be deceiving. While international shipping contributes 2.4% of global greenhouse gas emissions, business-as-usual could see this explode to a whopping 18% by 2050. As trade growth increases demand, today’s fleet burns the dirtiest transport fuels, and a new report shows the market doesn’t reward ship owners who invest in the latest fuel- and carbon-efficient technologies.

When you consider the scale of the sector’s emission reductions that need to start now to contribute to the COP 21 Paris Agreement target of 1.5°C to 2°C global warming, there’s clearly an…

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The “fuel” that’s helping America fight climate change isn’t natural gas

Power for the People VA

You’ve heard the good news on climate: after a century or more of continuous rise, U.S. CO2 emissions have finally begun to decline, due largely to changes in the energy sector. According to the Energy Information Agency (EIA), energy-related CO2 emissions in 2015 were 12% below their 2005 levels. The EIA says this is “because of the decreased use of coal and the increased use of natural gas for electricity generation.”

Is the EIA right in making natural gas the hero of the CO2 story? Hardly. Sure, coal-to-gas switching is real. But take a look at this graph showing the contributors to declining carbon emissions. Natural gas displacement of coal accounts for only about a third of the decrease in CO2 emissions.

Courtesy of the Sierra Club Beyond Coal Campaign, using data from the Energy Information Agency. Courtesy of the Sierra Club Beyond Coal Campaign, using data from the Energy Information Agency.

By far the biggest driver of the declining emissions is energy efficiency. Americans…

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Urbane Legends

Is Climate Change an Urban Legend?

US Issues

By Willis Eschenbach – Re-Blogged From

So we were sitting around the fire at the fish camp on the Colombia a few days ago, and a man said “Did you hear about the scientific study into meat preservatives?” We admitted our ignorance, and he started in. The story was like this:

“A few years ago there was a study done by some University, I can’t remember which one, but it was a major one. What they did was to examine the corpses of people who had died in Siberia, and those that had died in Washington State. Now of course the people in Siberia weren’t eating meat preservatives during their lives, and the Washington people were eating them. And when they dug up the graves and looked at the bodies, guess what they found?” 

the killer in the back seatUrban Legend: The Killer In The Back Seat SOURCE 

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Measuring and Monitoring Energy Efficiency

Defining Energy Efficiency

To begin, let us ask what is energy efficiency, what are it’s components and how is it measured.  To make comparisons we need to gather data using measures relevant to the industry in question, also to the input forms of energy, waste streams and the useful work performed.  In the case of a building we may use meters to measure consumption or utility bills and compare changes in consumption rates over time.

To an engineer, energy efficiency is the ratio of useful work over total energy input.  For example, a room air conditioner’s efficiency is measured by the energy efficiency ratio (EER). The EER is the ratio of the cooling capacity (in British thermal units [Btu] per hour) to the power input (in watts).

On a grander scale we may be looking improvements over an industry or sector, changing fuel types in a utility such as the conversion of a coal plant to the production of power fueled by natural gas to reduce the carbon load on the environment.  Efficiency may be measured by different metrics depending on the result sought and may include the environmental impact of waste streams.


Figure 1:  Historical Energy Use Graph  (1)

Whatever the exact yearly investment figure, the historical economic impact of efficiency is quite clear. As the graph () shows, efficiency has provided three times more of the economic services than new production since 1970:

The blue line illustrates demand for energy services (the economic activity associated with energy use) since 1970; the solid red line shows energy use; and the green line illustrates the gain in energy efficiency. While demand for energy services has tripled in the last four decades, actual energy consumption has only grown by 40 percent. Meanwhile, the energy intensity of our economy has fallen by half.

The area between the solid red line and the blue line represents the amount of energy we did not need to consume since 1970; the area between the dashed red line and the solid red line indicates how much energy we consumed since 1970.

The chart shows that energy efficiency met nearly three quarters of the demand for services, while energy supply met only one quarter.

“One immediate conclusion from this assessment is that the productivity of our economy may be more directly tied to greater levels of energy efficiency rather than a continued mining and drilling for new energy resources,” wrote Laitner. (1)

As noted in an article by the EIA;  The central question in the measurement of energy efficiency may really be “efficient with respect to what?” (2)  In general terms when discussing energy efficiency improvements we mean to perform more of a function with the same or less energy or material input.

Energy Efficiency Measures

Energy efficiency measures are those improvement opportunities which exist in a system which when taken will achieve the goals of achieving greater performance.  For example refer to Table 1 of Energy Efficiency Measures which can be effectively reduce energy consumption and provide an ROI of 5 or less years when applied to the commercial refrigeration industry.

energy efficient refrigeration4.jpg

Table 1:  Commercial Refrigeration Energy Efficiency Measures (3)

Government Action on Energy Efficiency

Energy efficiency has been put forward as one of the most effective methods in efforts to address the issue of Climate Change.  Recently, on February 19, 2015, President Obama signed Executive Order (EO) 13693.

“Since the Federal Government is the single largest consumer of energy in the Nation, Federal emissions reductions will have broad impacts.  The goals of EO 13693 build on the strong progress made by Federal agencies during the first six years of the Administration under President Obama’s 2009 Executive Order on Federal Leadership on Environmental, Energy and Economic Performance, including reducing Federal GHG emissions by 17 percent — which helped Federal agencies avoid $1.8 billion in cumulative energy costs — and increasing the share of renewable energy consumption to 9 percent.  

With a footprint that includes 360,000 buildings, 650,000 fleet vehicles, and $445 billion spent annually on goods and services, the Federal Government’s actions to reduce pollution, support renewable energy, and operate more efficiently can make a significant impact on national emissions. This EO builds on the Federal Government’s significant progress in reducing emissions to drive further sustainability actions through the next decade. In addition to cutting emissions and increasing the use of renewable energy, the Executive Order outlines a number of additional measures to make the Federal Government’s operations more sustainable, efficient and energy-secure while saving taxpayer dollars. Specifically, the Executive Order directs Federal agencies to:

– Ensure 25 percent of their total energy (electric and thermal) consumption is from clean energy sources by 2025.

– Reduce energy use in Federal buildings by 2.5 percent per year between 2015 and 2025.

– Reduce per-mile GHG emissions from Federal fleets by 30 percent from 2014 levels by 2025, and increase the percentage of zero emission and plug in hybrid vehicles in Federal fleets.

– Reduce water intensity in Federal buildings by 2 percent per year through 2025. ” (4)


Energy efficiency has gained recognition as a leading method to reduce the emissions of GHG’s seen to be the cause of climate change.  Under scrutiny, we find that there are different measures of efficiency across different industry, fuel types and levels.  For example on a micro-level, the functioning of a system may be improved by including higher efficiency components in it’s design, such as motors and pumps.

However, there are other changes which can improve efficiency.  Adding automated computer controls can improve a system level efficiency.   Utilities may change from coal burning to natural gas fired power plants, or industry may convert to a process to include for co-generation.  Battery storage and other technological improvements may come along to fill in the gap.

Historically Energy Efficiency measures have proven to be gaining ground by employing people with the savings earned when applying measures to reduce consumption.  These savings reverberate through the economy in a meaningful way, by reducing the need for the construction of more power plants as one example as we on an individual level.  We consume less energy, and using higher efficiency electronic equipment, and other energy savings measures at a consumer level, our communities are capable of more growth with existing energy supplies.

jEnergy production and consumption, as well as population growths also arise to other issues related to energy consumption, such as water consumption, water waste, and solid material waste.  Building with sustainable materials which promote healthy living environments is gaining importance as we understand the health impacts of a building’s environment on the health and well-being of the occupants.  Energy efficiency in the modern era, as we see from recent government mandates and sustainability programs, such as LEED’s for one, also includes for reductions in water intensity and incorporation of renewable energy programs as an alternative to increasing demand on existing utilities.



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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.



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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)

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