Electromagnetic absorption by water

The absorption of electromagnetic radiation by water depends on the state of the water.

The absorption in the gas phase occurs in three regions of the spectrum. Rotational transitions are responsible for absorption in the microwave and far-infrared, vibrational transitions in the mid-infrared and near-infrared. Vibrational bands have rotational fine structure. Electronic transitions occur in the vacuum ultraviolet regions.

Liquid water has no rotational spectrum but does absorb in the microwave region. Its weak absorption in the visible spectrum results in the pale blue color of water.

Absorption spectrum (attenuation coefficient vs. wavelength) of liquid water (red),^[1][2][3] atmospheric water vapor (green)^{[4][5][6][4][7]} and ice (blue line)^[8][9][10] between 667 nm and 200 μm.^[11] The plot for vapor is a transformation of data Synthetic spectrum for gas mixture ‘Pure H₂O’ (296K, 1 atm) retrieved from Hitran on the Web Information System.^[6]

Rotational spectrum

The water molecule is an asymmetric top, that is, it has three independent moments of inertia. Rotation about the 2-fold symmetry axis is illustrated at the left. Because of the low symmetry of the molecule, a large number of transitions can be observed in the far infrared region of the spectrum. Measurements of microwave spectra have provided a very precise value for the O−H bond length, 95.84 ± 0.05 pm and H−O−H bond angle, 104.5 ± 0.3°.^[13]

Part of the pure rotation absorption spectrum of water vapor

The three fundamental vibrations of the water moleculeν₁,O-H symmetric stretching
3657 cm⁻¹ (2.734 μm)ν₂, H-O-H bending
1595 cm⁻¹ (6.269 μm)ν₃, O-H asymmetric stretching
3756 cm⁻¹ (2.662 μm) 

The water molecule has three fundamental molecular vibrations. The O-H stretching vibrations give rise to absorption bands with band origins at 3657 cm⁻¹ (ν₁, 2.734 μm) and 3756 cm⁻¹ (ν₃, 2.662 μm) in the gas phase. The asymmetric stretching vibration, of B₂ symmetry in the point group C_2v is a normal vibration. The H-O-H bending mode origin is at 1595 cm⁻¹ (ν₂, 6.269 μm). Both symmetric stretching and bending vibrations have A₁ symmetry, but the frequency difference between them is so large that mixing is effectively zero. In the gas phase all three bands show extensive rotational fine structure.^[14] In the Near-infrared spectrum ν₃ has a series of overtones at wavenumbers somewhat less than n·ν₃, n=2,3,4,5… Combination bands, such as ν₂ + ν₃ are also easily observed in the near-infrared region.^[15][16] The presence of water vapor in the atmosphere is important for atmospheric chemistry especially as the infrared and near infrared spectra are easy to observe. Standard (atmospheric optical) codes are assigned to absorption bands as follows. 0.718 μm (visible): α, 0.810 μm: μ, 0.935 μm: ρστ, 1.13 μm: φ, 1.38 μm: ψ, 1.88 μm: Ω, 2.68 μm: X. The gaps between the bands define the infrared window in the Earth’s atmosphere.^[17]

The infrared spectrum of liquid water is dominated by the intense absorption due to the fundamental O-H stretching vibrations. Because of the high intensity, very short path lengths, usually less than 50 μm, are needed to record the spectra of aqueous solutions. There is no rotational fine structure, but the absorption bands are broader than might be expected, because of hydrogen bonding.^[18] Peak maxima for liquid water are observed at 3450 cm⁻¹ (2.898 μm), 3615 cm⁻¹ (2.766 μm) and 1640 cm ⁻¹ (6.097 μm).^[14] Direct measurement of the infrared spectra of aqueous solutions requires that the cuvette windows be made of substances such as calcium fluoride which are water-insoluble. This difficulty can alternatively be overcome by using an attenuated total reflectance (ATR) device rather than transmission.

In the near-infrared range liquid water has absorption bands around 1950 nm (5128 cm⁻¹), 1450 nm (6896 cm⁻¹), 1200 nm (8333 cm⁻¹) and 970 nm, (10300 cm⁻¹).^[19][20][15] The regions between these bands can be used in near-infrared spectroscopy to measure the spectra of aqueous solutions, with the advantage that glass is transparent in this region, so glass cuvettes can be used. The absorption intensity is weaker than for the fundamental vibrations, but this is not important as longer path-length cuvettes can be used. The absorption band at 698 nm (14300 cm⁻¹) is a 3rd overtone (n=4). It tails off onto the visible region and is responsible for the intrinsic blue color of water. This can be observed with a standard UV/vis spectrophotometer, using a 10 cm path-length. The colour can be seen by eye by looking through a column of water about 10 m in length; the water must be passed through an ultrafilter to eliminate color due to Rayleigh scattering which also can make water appear blue.^[16][21][22]

The spectrum of ice is similar to that of liquid water, with peak maxima at 3400 cm⁻¹ (2.941 μm), 3220 cm⁻¹ (3.105 μm) and 1620 cm⁻¹ (6.17 μm)^[14]

In both liquid water and ice clusters, low-frequency vibrations occur, which involve the stretching (TS) or bending (TB) of intermolecular hydrogen bonds (O–H•••O). Bands at wavelengths λ = 50-55 μm or 182-200 cm⁻¹ (44 μm, 227 cm⁻¹ in ice) have been attributed to TS, intermolecular stretch, and 200 μm or 50 cm⁻¹ (166 μm, 60 cm⁻¹ in ice), to TB, intermolecular bend^[11]

Visible regionEdit

Electronic spectrumEdit

Microwaves and radio waves

The pure rotation spectrum of water vapor extends into the microwave region.

Liquid water has a broad absorption spectrum in the microwave region, which has been explained in terms of changes in the hydrogen bond network giving rise to a broad, featureless, microwave spectrum.^[24] The absorption (equivalent to dielectric loss) is used in microwave ovens to heat food that contains water molecules. A frequency of 2.45 GHz, wavelength 122 mm, is commonly used.

Radiocommunication at GHz frequencies is very difficult in fresh waters and even more so in salt waters.^[11]

Atmospheric effects

Synthetic stick absorption spectrum of a simple gas mixture corresponding to the Earth’s atmosphere composition based on HITRAN data^[5] created using Hitran on the Web system.^[6] Green color – water vapor, WN – wavenumber (caution: lower wavelengths on the right, higher on the left). Water vapor concentration for this gas mixture is 0.4%.

Water vapor is a greenhouse gas in the Earth’s atmosphere, responsible for 70% of the known absorption of incoming sunlight, particularly in the infrared region, and about 60% of the atmospheric absorption of thermal radiation by the Earth known as the greenhouse effect.^[25] It is also an important factor in multispectral imaging and hyperspectral imaging used in remote sensing^[12] because water vapor absorbs radiation differently in different spectral bands. Its effects are also an important consideration in infrared astronomy and radio astronomy in the microwave or millimeter wave bands. The South Pole Telescope was constructed in Antarctica in part because the elevation and low temperatures there mean there is very little water vapor in the atmosphere.^[26]

Similarly, carbon dioxide absorption bands occur around 1400, 1600 and 2000 nm,^[27] but its presence in the Earth’s atmosphere accounts for just 26% of the greenhouse effect.^[25] Carbon dioxide gas absorbs energy in some small segments of the thermal infrared spectrum that water vapor misses. This extra absorption within the atmosphere causes the air to warm just a bit more and the warmer the atmosphere the greater its capacity to hold more water vapor. This extra water vapor absorption further enhances the Earth’s greenhouse effect.^[28]

In the atmospheric window between approximately 8000 and 14000 nm, in the far-infrared spectrum, carbon dioxide and water absorption is weak.^[29] This window allows most of the thermal radiation in this band to be radiated out to space directly from the Earth’s surface. This band is also used for remote sensing of the Earth from space, for example with thermal Infrared imaging.

As well as absorbing radiation, water vapour occasionally emits radiation in all directions, according to the Black Body Emission curve for its current temperature overlaid on the water absorption spectrum. Much of this energy will be recaptured by other water molecules, but at higher altitudes, radiation sent towards space is less likely to be recaptured, as there is less water available to recapture radiation of water-specific absorbing wavelengths. By the top of the troposphere, about 12 km above sea level, most water vapor condenses to liquid water or ice as it releases its heat of vapourization. Once changed state, liquid water and ice fall away to lower altitudes. This will be balanced by incoming water vapour rising via convection currents.

Liquid water and ice emit radiation at a higher rate than water vapour (see graph above). Water at the top of the troposphere, particularly in liquid and solid states, cools as it emits net photons to space. Neighboring gas molecules other than water (e.g. Nitrogen) are cooled by passing their heat kinetically to the water. This is why temperatures at the top of the troposphere (known as the tropopause) are about -50 degrees Celsius.

Credits: wikipedia

Net Zero Goals Impossible Without CCUS

Carbon capture, utilization and storage (CCUS)

 is the only group of technologies that contributes both to reducing emissions in key sectors directly and to removing CO2 to balance emissions.

“Reaching net zero will be virtually impossible without CCUS,” the International Energy Agency (IEA) said in a recent report on the role of carbon capture, utilization, and storage in the energy transition.

Many governments, especially in mature economies, as well as all oil and gas supermajors, also seem to concur that carbon capture and storage is a critical part in achieving the emission reduction targets and net-zero goals that various countries and businesses, including the European oil majors, are pursuing.  

Governments and oil firms are betting big on CCUS, but a large-scale deployment of carbon capture and storage projects is still years away.

Technology and costs continue to be significant hurdles on the road to making CCUS a vast and truly global industry capable of abating emissions not only from new energy generation, such as the production of blue hydrogen, but also from existing energy systems and from heavy industries such as cement, steel, or chemicals production.

Governments and industry need to invest hundreds of billions of U.S. dollars over the next two to three decades if CCUS stands a chance of becoming the pillar of the energy transition and “the only group of technologies that contributes both to reducing emissions in key sectors directly and to removing CO2 to balance emissions that are challenging to avoid,” as the IEA describes it in its report.

The Potential Is There

Various studies and pilot projects have shown that CCUS has the potential to become the industry that will help heavy industry and fossil fuel industries to cut emissions.

Globally, there are more than 60 operational CCS projects of varying capture capacity, with the United States leading with 28 percent of those operational projects, followed at quite a distance by China, Canada, Japan, and Australia, Wood Mackenzie said in a report on the North Sea potential to net-zero last month. 

Most recently, Norway has just launched the Longship project, which includes funding for the Northern Lights joint project of supermajors Equinor, Shell, and Total to capture CO2 from industrial sources in the Oslo fjord region (cement and waste-to-energy) and shipping of liquid CO2 from these industrial capture sites to an onshore terminal on the Norwegian west coast. The government funding is US$1.8 billion (16.8 billion Norwegian crowns) out of the total US$2.7 billion (25.1 billion crowns) project costs.

“For Longship to be a successful climate project for the future, other countries also have to start using this technology,” Norway’s Prime Minister Erna Solberg said.

Government Support Is Critical

The Norwegian project goes to show what analysts have been saying about CCUS all along: government support and sponsorship is critical for getting this industry off the ground, and large-scale deployment is essential to achieving meaningful emissions reductions on a global scale.

To overcome those constraints, governments and industries need to improve technologies, but they also need to cut costs to make CCUS feasible and not so cost-prohibitive.

“A significant scale-up of deployment is needed to provide the momentum for further technological progress, cost reductions and more widespread application in the longer term. Without a sharp acceleration in CCUS innovation and deployment over the next few years, meeting net-zero emissions targets will be all but impossible,” the IEA said in its report.

“The rapid deployment hinges critically on a massive increase in government support, as well as new approaches to public and private investment,” the Paris-based agency says.

Big Oil has embraced CCUS as one of the pathways to emission reductions, as many European majors have pledged to become net-zero businesses by 2050 or sooner. Shell, BP, Total, Equinor, and ENI are all working on and investing in carbon capture and storage projects.

Investment Is Critical Too

However, the industry and governments need to invest hundreds of billions of U.S. dollars over the next three decades in order to make CCUS the game-changing emission-cutting industry that the IEA envisages today.

The UK alone will need around US$78 billion (60 billion British pounds) in investments in CCUS over the next 30 years, and even higher investments in offshore wind and green hydrogen, if it is to build a net-zero energy system, WoodMac’s Chairman and Chief Analyst Simon Flowers said.

Commercialization is still some way off due to technical challenges and the need for the carbon price to be at least double today’s carbon price, according to the energy consultancy.  

“Significant policy incentives such as carbon taxes and the development of CCUS clusters are likely needed to help CCUS be competitive,” WoodMac said in its report about the potential in the UK Continental Shelf.

Globally, the world will need CCUS to reduce emissions from existing infrastructure as renewable energy and electric vehicles (EVs) are not enough to curb the effects of climate change on the planet. Without the right policies and support, large-scale CCUS could be a nearly impossible task, according to WoodMac.

“Emissions will continue increasing unless there is an incentive to rationalize the carbon-heavy assets or retrofit with carbon capture and storage — a herculean task without an appropriate tax on carbon,” Prakash Sharma, head of markets and transitions for Asia-Pacific at Wood Mackenzie, said.

“If the world is to achieve the Paris goal for global warming, green hydrogen and CCUS will have to be part of the solution, and that means sustained policy support. Attracting the investment to lift these technologies from the demonstration phase to full commercialization needs higher carbon prices and, ultimately, a coherent, global carbon policy,” WoodMac said in its Energy Transition Outlook 2020.

Industries and governments recognize that CCUS could play a pivotal role in the energy transition, but a lot more efforts, policy support, government funding, corporate investments, technology improvements, and cost cuts are needed to make CCUS the game-changer in the fight against climate change.  

Thermal conductivity, R-Values and U-Values simplified!

Thermal Conductivity of insulating materials

The primary feature of a thermal insulation material is its ability to reduce heat exchange between a surface and the environment, or between one surface and another surface. This is known as having a low value for thermal conductivity. Generally, the lower a material’s thermal conductivity, the greater its ability to insulate for a given material thickness and set of conditions.

Thermal conductivity, also known as Lambda (denoted by the greek symbol λ), is the measure of how easily heat flows through a specific type of material, independent of the thickness of the material in question.

The lower the thermal conductivity of a material, the better the thermal performance (i.e. the slower heat will move across a material).

It is measured in Watts per Metre Kelvin (W/mK).

To allow you to get a feel of insulating materials – their thermal conductivity varies between about 0.008 W/mK for vacuum insulated panels (so these are the best, but very expensive!) to about 0.061 W/mK for some types of wood fibre.

K-Values

K-value is simply shorthand for thermal conductivity. The ASTM Standard C168, on Terminology, defines the term as follows:

Thermal conductivity, n: the time rate of steady state heat flow through a unit area of a homogeneous material induced by a unit temperature gradient in a direction perpendicular to that unit area.

This definition is really not that complex. Let’s take a closer look, phrase by phrase.

Time rate of heat flow can be compared to water flow rate, e.g., water flowing through a shower head at so many gallons per minute. It is the amount of energy, generally measured in the United States in Btus, flowing across a surface in a certain time period, usually measured in hours. Hence, time rate of heat flow is expressed in units of Btus per hour.

Steady state simply means that the conditions are steady, as water flowing out of a shower head at a constant rate.

Homogeneous material simply refers to one material, not two or three, that has a consistent composition throughout. In other words, there is only one type of insulation, as opposed to one layer of one type and a second layer of a second type. Also, for the purposes of this discussion, there are no weld pins or screws, or any structural metal passing through the insulation; and there are no gaps.

What about through a unit area? This refers to a standard cross-sectional area. For heat flow in the United States, a square foot is generally used as the unit area. So, we have units in Btus per hour, per square feet of area (to visualize, picture water flowing at some number of gallons per minute, hitting a 1 ft x 1 ft board).

Finally, there is the phrase by a unit temperature gradient. If two items have the same temperature and are brought together so they touch, no heat will flow from one to the other because they have the same temperature. To have heat flow by conduction from one object to another, where both are touching, there must be a temperature difference or gradient. As soon as there is a temperature gradient between two touching objects, heat will start to flow. If there is thermal insulation between those two objects, heat will flow at a lesser rate.

At this point, we have rate of heat flow per unit area, per degree temperature difference with units of Btus per hour, per square foot, per degree F.

Thermal conductivity is independent of material thickness. In theory, each slice of insulation is the same as its neighboring slice. The slices should be of some standard thickness. In the United States, units of inches are typically used for thickness of thermal insulation. So we need to think in terms of Btus of heat flow, for an inch of material thickness, per hour, per square foot of area, per degree F of temperature difference.

After picking apart the ASTM C168 definition for thermal conductivity, we have units of Btu-inch/hour per square foot per degree F. This is the same as the term K-value.

C-Values

C-value is simply shorthand for thermal conductance. For a type of thermal insulation, the C-value depends on the thickness of the material; K-value generally does not depend on thickness (there are a few exceptions not in the scope of this article). How does ASTM C168 define thermal conductance?

Conductance, thermal, n: the time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces.

ASTM C168 then gives a simple equation and units. In the inch-pound units used in the United States, those units are Btus/hour per square foot per degree F of temperature difference.

The words are fairly similar to those in the definition for thermal conductivity. What is missing is the inch units in the numerator because the C-value for a 2-inch-thick insulation board is half the value as it is for the same material 1-inch-thick insulation board. The thicker the insulation, the lower its C-value.

Equation 1: C-value = K-value / thickness

R-Values

The R-value is a measure of resistance to heat flow through a given thickness of material.  So the higher the R-value, the more thermal resistance the material has and therefore the better its insulating properties.

The R-value is calculated by using the formula

Where:

l is the thickness of the material in metres and

λ is the thermal conductivity in W/mK.

The R-value is measured in metres squared Kelvin per Watt (m²K/W)

For example the thermal resistance of 220mm of solid brick wall (with thermal conductivity λ=1.2W/mK) is 0.18 m²K/W.

If you were to insulate a solid brick wall, you simply find the R-value of the insulation and then add the two together. If you insulated this with 80mm thick foil-faced polyisocyanurate (with thermal conductivity λ=0.022W/mK and R-value of 0.08 / 0.022 = 3.64 m²K/W), you would have a total R-value for the insulated wall of 0.18 + 3.64 = 3.82 m²K/W. Therefore it would improve the thermal resistance by more than 21 times!

U-Values

The U value of a building element is the inverse of the total thermal resistance of that element. The U-value is a measure of how much heat is lost through a given thickness of a particular material, but includes the three major ways in which heat loss occurs – conduction, convection and radiation.

The environmental temperatures inside and outside a building play an important role when calculating the U-value of an element. If we imagine the inside surface of a 1 m² section of an external wall of a heated building in a cold climate, heat is flowing into this section by radiation from all parts of the inside the building and by convection from the air inside the building. So, additional thermal resistances should be taken into account associated with inside and outside surfaces of each element. These resistances are referred to as R_{si  and} R_so respectively with common values 0.12Km²/W and 0.06Km²/W for the internal and external surfaces, respectively.

This is the measure that is always within Building Regulations. The lower the U-value is, the better the material is as a heat insulator.

This is calculated by taking the reciprocal of the R-Value and then adding convection and radiation heat losses, as follows.

U = 1/ [ R_si + R₁ + R₂ +… + R_so ]

In practise this is a complicated calculation, so it is best to use U-Value calculation software.

Units are in Watts per metre squared Kelvin (W/m²K).

As a guide an uninsulated cavity wall has a U-Value of approximately 1.6 W/m²K, while a solid wall has a U-Value of approximately 2 W/m²K

Using U-Values, R-Values and Thermal conductivity

If you are confronted with thermal conductivity, R-values and U-values going forward, here are 3 simple things to remember, to make sure you get the best insulating product.

•  Higher numbers are good when comparing the Thermal Resistance and R-Values of products.
•  Low numbers are good when comparing U-Values.
•  The U-Value is the most accurate way to judge a material’s insulating ability, taking into account all the different ways in which heat loss occurs, however it is more difficult to calculate.

California

More Rolling Blackouts

California grid operator warns of rotating power outages in record heat wave

The California Independent System Operator (ISO) declared a “Stage 2” power emergency late on Saturday, warning that rotating power outages were possible amid a record heat wave.

A Stage 2 power emergency means the ISO has taken all mitigating actions but can no longer provide its expected energy requirements.

Temperatures of up to 125 degrees Fahrenheit (49 Celsius) were set to punish California through the Labor Day weekend, raising the risk of wildfires and rolling blackouts.

California Governor Gavin Newsom on Friday declared a state of emergency, a proclamation that allows power plants to operate beyond normal limits through the three-day holiday weekend.

The National Weather Service (NWS) forecast a heat wave carrying “rare, dangerous and very possibly fatal” temperatures across Southern California for the holiday weekend.

State officials urged Californians to turn off unnecessary appliances and lights to help avoid blackouts from an overwhelmed power grid.

Authorities also asked power generators to delay any maintenance until after the weekend to prevent blackouts like the two nights of rolling outages in mid-August as residents cranked up their air conditioning.

This weekend was expected to be hotter than the one in mid-August that helped trigger the second- and third-largest forest fires in California history. Those fires are still burning.

Death Valley in California’s Mojave desert registered one of the hottest air temperatures recorded on the planet of 130F (54C) on Aug. 17, and highs of around 124 were expected there on Sunday, the NWS said.

San Francisco-based power provider PG&E Corp said on Saturday that it may be asked by the grid operator to turn off power due to the “extreme heat.” It urged customers to conserve power.

The company said it may have to cut power early on Monday and Tuesday in parts of Northern California as hot, dry winds are expected to threaten the region.

PG&E said its potential power shut-offs may impact parts of 17 counties, which would include about 103,000 customers.

The following is a contributed article by Jurgen Weiss, Principal at The Brattle Group.

Reducing GHG emissions 80% by 2050 relative to 1990 levels — often referred to as an “80 by 50” goal — is quickly becoming the consensus decarbonization target, and more and more states and utilities are committing to a goal of this kind. Increasingly, many stakeholders are calling for the pursuit of even more ambitious goals, such as striving for 100% renewable energy or net-zero emissions by 2050. However, just as many voices suggest that a 100% clean energy goal is unnecessary, infeasible or too expensive.

All three of these arguments — that a 100% goal is unnecessary, infeasible and too expensive — are questionable and quite likely incorrect.

A 100% carbon-free energy supply for electricity, buildings, transportation and portions of the industrial sector likely is necessary to support an 80% economy-wide decarbonization by 2050, because decarbonizing other sectors, such as agriculture and certain industries, is harder and more expensive. Achieving 80% economy-wide reductions therefore likely requires a carbon-free energy sector so that there is room for residual emissions in other sectors. This is particularly true for the electricity sector, which likely will grow significantly as we electrify significant portions of transport, buildings and industrial energy supply. For this reason, this article focuses on the feasibility and likely cost of a 100% emissions-free electricity sector.

Operating a 100% carbon-free electricity sector by 2050 certainly is feasible. When questioning how a 100% carbon-free electricity system can function, people often confuse the terms “carbon-free” and “dispatchable.” Our ability to operate an electricity system with high shares of variable renewable energy resources — in the U.S. primarily wind and solar PV, with smaller amounts of hydro, biomass and geothermal — has dramatically improved over the past couple of decades.

Challenges on road to 100%

It is nevertheless true that, as the share of renewable generation grows towards 100%, new challenges emerge that require significant amounts of dispatchable generation resources — especially those that can provide power for longer periods of time when the wind doesn’t blow and the sun doesn’t shine. Because periods of low wind, solar and hydro generation can last several days, weeks, or go through seasonal or even multi-year cycles, existing battery storage technologies would be prohibitively expensive to address this challenge. But, while still expensive, we already have storage technologies that can address this problem, and new ones are emerging rapidly.

Beyond batteries, there are three promising storage technologies that can help us deal with the challenges of a 100% renewable electricity system: gravity, heat and electrolysis. There are a number of proposed or emerging low-cost storage options using gravity to store vast amounts of energy for long periods of time, including pumped hydro, lifting blocks of concrete on a tower or putting rocks on a train that gets pulled up a hill, or literally cutting a cylinder into granite and lifting it. Heat (or cold) can also be stored daily, seasonally or perhaps even longer. For example, the city of Toronto uses the natural temperature of Lake Ontario to cool buildings in the summer, and geothermal systems can be designed to “pre-heat” the ground in the summer and use the same heat in the winter.

Wind and solar electricity can also be used to make hydrogen from water through electrolysis. The hydrogen can be stored directly or it can be used along with CO2 captured from carbon-neutral processes (such as bio-feed stocks or from the air) to make methane (CH4) and other energy-dense substances such as methanol, ammonia or even a carbon-free substitute for jet fuel. These chemical processes, sometimes called “P2X” (Power to “fill in the blank”), are still expensive today, but for a variety of reasons, significant capital is already flowing into their development and significant cost reductions likely are feasible with further technological development.

The important point is that the process for turning water and electricity into hydrogen, methane and other substances is well understood and functioning today. We can store hydrogen, methane or liquids for long periods of time and convert them back into electricity with fuel cells or gas turbines when we need to — thus creating a carbon-neutral, dispatchable resource to fill in the gaps when we do not have enough solar and wind power to meet electricity demand. In addition to these options, it is also possible that carbon capture and sequestration will become more cost-effective for removing the carbon from easily storable fossil fuels that can be used to power dispatchable generation when needed.

Not too expensive

Finally, a 100% carbon-free energy system is unlikely to be too expensive. Even though storage and carbon-free dispatchable resources are currently expensive when compared to, say, storing and using natural gas in the United States, there is no obvious way of telling whether a 100% renewable energy system using emerging technologies to balance the electric system will lead to substantially higher energy costs for consumers.

Meeting the large portion of demand that can be met directly with wind, solar, batteries, demand response and other existing technologies before running into long-term storage and dispatchability issues is getting cheaper all the time. Even only five years ago, few industry participants anticipated the low cost of solar and storage devices already achieved today. In many parts of the country, un-subsidized new renewable resources are already cheaper than new fossil-fueled plants and, in the near future, some of them will be cheaper than operating existing fossil plants.

Even with the additional cost of new transmission infrastructure needed to connect all these renewable energy resources, the average cost for this portion of a carbon-free electricity sector will likely not be dramatically higher than the average cost of electricity today. Hence, even if the dispatchable portion of a future 100% carbon-free grid were quite a bit more expensive, there is a good chance that resulting average customer rates remain at or below historic values.

As an aside, comparing the projected costs of carbon-neutral new approaches to dealing with the “last 20-30%” of getting to 100% to the current fossil-fuel-based solutions (such as natural gas-fired power generation) likely overstates the cost of these new approaches. Since operating a fossil-fuels based infrastructure involves a significant amount of fixed costs, the costs per kWh of fossil-based energy would increase if the overall volume of fossil-based energy production declines, as it most likely will.

In this context, today’s relatively low energy costs are quite unusual. According to the U.S. Energy Information Administration, the average share of household disposable income spent on energy has been around 4-5% in recent years, down from 6-8% in the 1970s and 1980s. Hence, the U.S. economy has been through periods with energy costs being 50-100% higher than they are now without any catastrophic impacts and without stunting economic growth.

Electrification shift

Importantly, achieving the stated 80% economy-wide decarbonization goal will almost certainly require shifts towards electric cars and electric heating. The two primary technologies involved, electric motors and heat pumps, already are significantly more efficient than their fossil counterparts. Therefore, shifting to electric transportation and heat pumps could potentially provide significant cost savings to consumers.

The bottom line is that, given all the progress we are likely to make, we likely will be able to reduce the cost of a significant portion of our energy consumption. Consequently, there is no obvious reason to believe that energy will become unaffordable, even if we have to use relatively expensive means to decarbonize perhaps the last 20-30% of our electricity supply by creating carbon-neutral and dispatchable sources of power generation.

Ironically, a lower-cost outcome is more likely if we commit to a 100% rather than just 80% carbon-free electricity sector. Committing to 100% will provide additional certainty for innovations and cost reductions, such that the dispatchable carbon-free solutions will become available in time to decarbonize the last 20-30% of our electricity supply.

I am thus optimistic that (1) we will be able to develop and operate a 100% carbon-free electricity system to achieve 80% economy-wide decarbonization within 30 years, and that (2) the cost to consumers (and businesses) of such a system will not be fundamentally different from costs the U.S. has seen historically or that are experienced in many other developed countries today. In fact, I am virtually certain that such a system will be less expensive than the consequences of climate change if we do not manage an expedited transition to such a system.

We should be much more worried about our ability to ramp up our efforts to get there in time, given the discrepancy between the current pace of change and the much faster pace that almost certainly will be needed over the next decades. Unless we keep our foot on the clean-energy accelerator, we likely won’t achieve anything near even an 80% carbon-free economy and hence the difficult question of how to manage a fully decarbonized electric system won’t have to be answered. And that would be a shame, or much worse.

Alternating Current (AC) vs Direct Current (DC)

The current (electric charge) only flows in one direction in case of DC. But in AC electric charge changes direction periodically. Not only current but also the voltage reverses because of the change in the current flow.

The AC versus DC debate personifies the War of Currents, as it is now called, in which the two giants of electric power were embroiled in the late 1890s. Thomas Edison, the proprietor of Direct Current, was so threatened by Tesla’s invention that, in order to discredit Alternating Current, he resorted to falsely misleading Americans. Apprehensive about losing his royalties to this new technology, Edison went so far as to electrocute an elephant to show Alternating Currents’ fatal dangers.

However, this did not stop Tesla from fulfilling his dream of powering the United States with cheap and highly efficient energy. Even now, we see long and thick wires tightly strung between soaring electrical towers like the strings of a guitar. AC took over the throne and reigned for a century, dominating households, offices and buildings, until now, when DC seems to be gradually making a comeback. Why did AC fare so well? And why might DC make a comeback? 

Why is AC better?

Despite now having the technology to transmit DC over grids across long distances, we still persist to use AC. AC is pushed to higher voltages to overcome resistance, and when the power reaches the user, it is stepped down and rectified to power, for example, a computer. However, these technologies, like renewable technologies, not only cost a fortune, but their efficiency might also be questionable. Yes, DC provides stable outputs, but higher efficiency is achieved after eliminating losses.

Although the losses might be less than those incurred with AC, the step-up/down factor comes into play. The simplicity with which AC voltages can be modulated and transported is still unmatched, which is why AC might be still preferred. Both sources of power are excellent in their own ways, so determining who is triumphant would depend on the criteria under contention – the playing field. The judgment essentially relies on the application of the power.

Nowadays, both work in tandem. AC runs above us on wires, like the lines of an empty diary that terminate at your house. The AC voltage then is converted to DC with a rectifier, like the adaptor that your charger contains, to power household devices, such as bulbs, lamps and other appliances. The War of Currents might not be as dramatic as it once was, but it still subtly exists.

Clean energy in U.S. a $1.3 trillion annually

CLEAN ENERGY: A new study estimates the “green economy” in the U.S. generates $1.3 trillion in annual revenue, or about 7% of GDP. (Bloomberg)

ALSO:
• Google announces plans for $150 million in clean energy investment; the figure represents about 0.1% of the company’s 2018 revenue. (CNET)
• A growing number of colleges and universities seek help from the private sector to run their utilities and meet emission-reduction targets. (Utility Dive)
• ExxonMobil is spending millions on clean energy researchers, which some critics say raises questions about scientific independence. (Axios)

***SPONSORED LINK: Register for Infocast’s Southeast Renewable Energy Summit, October 28-30 in Atlanta, to meet the top players in the market and explore the new renewable energy growth opportunities in the region. You’ll engage in networking and deal-making exchanges with the decision-makers driving the Southeast industry forward. Sign up today!***

EPA:
• Staffers say the California EPA office was bypassed as the Trump administration escalated its political dispute with the state. (New York Times)
• An EPA attorney the political atmosphere means “things have basically come to a standstill here” with regards to enforcement actions. (The Revelator)

CLIMATE:
• Maryland releases its long-awaited plan to cut greenhouse gas emissions, with a target of 44% below 2006 levels by 2030. (Baltimore Sun)
• A Florida Republican says a recent climate change discussion in that state’s legislature reflects a new generation of conservatives “who aren’t so much in denial about some of these issues.” (WJCT) 

OIL & GAS:
• California inspectors are working to determine the cause of yesterday’s explosions and fire at NuStar Energy’s East Bay oil storage facility that destroyed thousands of gallons of fuel and and prompted a hazardous materials emergency. (Associated Press)
• A slump in oil prices has brought job creation around the oil and gas industry in the Permian Basin to a halt and led to a steady trickle of layoffs. (Reuters)

NATURAL GAS:
• Columbia Gas of Massachusetts creates a new position of chief safety officer after a spate of mishaps and brings in an executive well known in the state’s industry. (Boston Globe)
• Southern California Gas Co. is trying to find the source of a “mysterious” ground fire at the Aliso Canyon natural gas storage facility. (Associated Press)

BIOFUELS: Ethanol advocates say the Trump administration has reneged on its promise to boost biofuel demand with a proposal that allows more waivers for oil refineries. (Cedar Rapids Gazette)

UTILITIES:
• Top Exelon official Anne Pramaggiore retires as the company receives federal subpoenas connected to its Illinois lobbying activities. (Chicago Sun Times)
• A U.S. bankruptcy judge says he will confirm FirstEnergy Solutions’ bankruptcy plan. (Crain’s Cleveland Business)

NUCLEAR:
• An engineer at the Argonne National Laboratory near Chicago uses supercomputers to determine what advanced nuclear reactor designs might work. (Energy News Network)
• The U.S. Supreme Court rules that the federal government does not have to restart construction on a nuclear fuel facility in South Carolina. (Post and Courier) 

***SPONSORED LINK: The Midwest energy landscape is changing. Find out what’s in store for the policy and business side of solar, storage, and wind energy at Solar and Storage Midwest. Join us November 14-15 in Chicago.***

SOLAR: A new study says adding solar to homes in New Jersey and Pennsylvania provides the greatest increases in their value nationally. (Pittsburgh City Paper)

COMMENTARY: “What the events in California and Miami and Houston tell us is that we are living through the risks of an altered climate now, not a hundred years from now.” (New York Times)

CREDITS 

Arkansas Weatherization Program

Up to ^$1,058 Incentive: Program
Source: Entergy Arkansas
Category: Whole House, New Home Programs, Home / Residential, Weatherization, Insulation & Air Sealing, Air Conditioning & Fans, Central Heating
To Qualify:
The Arkansas Weatherization Program (AWP) is a utility funded program for all Arkansans that have utility service with one or more of the participating utilities. This program will include a pre-audit and a list of recommendation of corrective measures to be made

Air Conditioning Tune-Ups, Duct Sealing and Air Sealing

Air Conditioning Tune-Ups
The air conditioning tune-up helps each home’s system to run more efficiently and provides better comfort to residents while lowering energy costs. This is achieved by a certified technician cleaning your system and adjusting refrigerant charge.

Duct Sealing
A duct system that is well-designed and properly sealed can make your home more comfortable, energy efficient and safer. Duct sealing is available for homes with electric heating and cooling systems whose ductwork is significantly leaky.

Air Sealing
Reducing the amount of air that leaks in and out of your home is a cost-effective way to cut heating and cooling costs, improve durability, increase comfort and create a healthier indoor environment. Air sealing is available for homes with electric heating and cooling systems whose envelope is significantly leaky.

Energy Survey

An Entergy Arkansas-qualified field technician will perform an energy survey of your property’s common areas at no cost. This will identify ways to improve your property’s energy efficiency. At the end of the survey, the technician will provide you with a summary of recommendations.

Summer Advantage Program^$50 to ^$80Incentive: Program
Source: Entergy Arkansas
Category: Whole House, New Home Programs, Home / Residential, Air Conditioning & Fans
To Qualify:
Here’s how it works. Air conditioners require a lot of energy in the summer. But through the Summer Advantage Program, Entergy will install a small device called a Direct Cycling Unit (DCU) on your air conditioner. During hot summer afternoons when air conditioners are working overtime to keep homes cool, Entergy can activate your DCU and decrease the amount your air conditioner runs during peak energy hours. This helps Entergy lower its operating costs � which helps everyone save. Plus, your enrollment in the Summer Advantage Program means you will earn an annual cash reward based on your participation. If you run 50 percent less, you will earn $25 for installng the DCU plus $25 each year for your participation during cold season. If you run 75 percent less, you will earn $40 for installng the DCU plus $40 each year for your participation during cold season.

What is Net Zero?

A Net-Zero home is one that has the ability to produce as much energy as it consumes. This is done by having a tight envelope and reducing consumption.

1. Higher Market Value

While the initial cost of construction may be higher, the benefits of a Net-Zero home make up for the expense in the end.

The extra cash spent during the construction of a Net-Zero home is a strong investment as the market value of these homes are highly sought after.

2. Lower Long-Term Ownership Costs

Installing the most energy efficient Heating, cooling, water heating, lighting, appliances, and the dozens of electronics we plug in every day are likely to add up to more than the difference in mortgage payments so you’ll come out ahead. Plus, many Net-Zero homes are able to produce more energy than they consume so you could end up getting paid for the energy you add to the grid.

3. Increased Comfort

One of the key elements of a Net-Zero home is lots of insulation and airtight construction. This means that there are no more cold drafts in the winter causing you to grab a sweater, and no more hot rooms in the summer that do not ever seem comfortable. Extra thick walls and windows also block out more noise making your home a quiet refuge, and the use of fewer chemicals throughout the home make the air better to breathe.

4. Earth Friendly

Using smart energy sources like solar power means no carbon emissions to poison the air and contribute to climate change. Avoiding nonrenewable energy sources reduces carbon emissions. Not depending on fossil-fuel-burning power plants for electricity is just as Earth-friendly.

5. A Net-Zero Home Will Set You Free

Having a Net-Zero home means that you’ll no longer be at the mercy of fluctuating energy prices and months of extreme temperatures that break the bank. 

If the electricity ever goes out, the higher levels of insulation will keep your home comfortable for longer stretches of time and your overall energy needs would be so low that backup power is easier to provide in the event of a long-term outage. Not being bound to the energy companies will set you free.

Your changes makes a huge impact

It’s not easy to step out ahead of the pack and make bold changes that go against the conventional lifestyle. It takes courage and leadership to know that every small step towards sustainable living can make a difference. 

 A Net-Zero home can be a symbol of this adaptation. It can be an inspiration for the neighbors or the next generation.