Global Warming, Coal Combustion and Sea Level Rise
- Aug 29, 2012 8:46 pm GMTJul 7, 2018 12:34 am GMT
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Since about 1960, the Arctic annual average temperature has increased about 2 to 3 C (3.6 to 5.4 F). The world average temperature, WAT, has increased by about 0.7 C (1.3 F) over the same time period. The WAT increase of less than 1 C since about 1850 is likely too small to have caused the large temperature increase in the Arctic of recent decades.
A much more likely cause is soot, SOx and ash particulate deposits on snow and ice surfaces have accelerated the melting, especially due to the increased emissions from coal combustion by China, India, Brazil, etc., since about 1960. The resulting snow and ice is slightly darker than without the deposits and melts easier. As it melts, it becomes darker thereby accelerating the melting; an unstoppable positive feedback. http://www.nola.com/news/index.ssf/2011/04/soot_may_be_key_to_rapid_arct...
This process started in the 1960s, about the time China, India, Brazil, etc., were ramping up coal combustion without efficient air quality control, AQS, systems to produce the goods for the markets of the US, Europe, Japan, etc. Business leaders were closing domestic plants and opening them in China, India, Brazil, etc.
An indication of Arctic warming is the sea ice volume (extent x thickness) decreasing since about 1960.
The particulate deposits on snow and ice surfaces likely contributed to the ending of the Little Ice Age, LIA, and the onset of the Present Warm Period, PWP. Whereas the quantity of coal consumption was much less than at present, its combustion process was much “dirtier” regarding particulate emissions.
The atmospheric CO2 ppMv started to rise during the late 1800s and therefore, was not a factor in the ending of the LIA and the onset of the PWP; other GW factors were more influential.
CO2, among other manmade GW factors, such as urbanization, industrial agriculture, deforestation, etc., will add to the PWP cycle. All these factors would be less with fewer people and a lesser resource and energy consumption per capita.
Note: The Arctic was in a cooling phase from 1900 to 1925, a warming phase from 1925 to 1960, a cooling phase from 1960 to 1990, and a slightly warming phase from 1990 to Present, all while CO2 ppMv was steadily increasing, which indicates other GW factors are influential.
The particulate deposits in the Arctic have affected the Northern Hemisphere climate (the refrigerator of the North is shrinking, temperatures are rising, temperature distributions and weather patterns are changing), because arctic ice reflects about 80% of solar energy into space, whereas water reflects only about 10%.
Present trends indicate the Arctic float ice will be absent during summer within a few years which will significantly affect Northern Hemisphere weather and further increase Arctic summer temperatures. Most of this melting is due to particulate deposits from coal combustion, including particulates entrained in precipitation.
The CO2 ppMv increasing from about 0.0316% in 1960 to 0.0390% in 2011 could not have been THE major factor for the Arctic temperature increase during that time period. Particulate deposits act near-instantly regarding Arctic warming, whereas CO2 emissions have a much longer time constant.
Note: Methane is increasingly released from rapidly-warming tundra areas in Siberian Arctic areas; an unstoppable positive feedback. A methane molecule traps about 21 times the energy trapped by a CO2 molecule. Methane has an atmospheric lifetime of about 12 years vs. CO2 about 50-200 years.
COAL COMBUSTION SINCE THE EARLY 1800s
Dirty combustion of coal was common from the early 1800s to about 1950 when low-efficiency AQC systems (cyclonic separators, precipitators, fabric filters, scrubbers, etc.) were being installed in the US, Europe, Japan, etc., because smoking chimneys were no longer considered a sign of progress and prosperity. This was mostly not the case in the developing nations, such as China, India, Brazil, etc.
With highly efficient AQC systems, only the submicron particles, of which there are many, do not get collected. They take longest to settle and some may never settle, except as entrained in precipitation. Hence, the increasing aerosol nature of the troposphere. Fuel-injected internal combustion engines, especially diesel engines, produce millions of submicron particles per gallon of fuel.
Note: Diesel fuel and airplane jet fuel contain about 0.01% ash; the US EPA standard is 0.02% ash. That means for every 1,000 lb (about 140 gallon) of jet fuel combusted, about 1 lb is released as submicron particles mostly at 30,000-45,000 ft elevation. Each submicron particle consists of only a few dozen molecules. The water vapor from combustion condenses and freezes onto the particles from combustion, which, after a plane length, agglomerate to become large enough, 0.4-0.7 micron (millionth of a meter), to refract sunlight and become visible as contrails that spread out to become veil-like clouds over large areas of the sky. They eventually “disappear”, but give the sky a permanent, grayish haze. Because all this takes place in the upper troposphere, these ice-covered, submicron particles stay at that elevation, largely undisturbed by the weather, for some years. As such pollution is added at a greater rate than it settles, the intensity of the grayish haze has increased during the jet plane era. The GW potential, plus or minus, of this upper tropospheric change has not yet been quantified.
Note: Lower troposphere soot and particulates have a cooling effect which counteracts other GW factors, such as increasing CO2 ppMv.
Coal contains about 10% ash, on average. After combustion about 80% of the ash becomes flyash, the other 20% becomes bottom ash. It takes about 1.1 lb of coal, 10,000 Btu, to produce a kWh which yields 0.11 lb of ash of which 0.088 lb is flyash.
A modern AQC system collects about 99.9% of the flyash, whereas a mediocre AQS system collects about 95% or less, i.e., particulate emissions are either 1 lb in a 1,000 lbs of flyash, or greater than 50 lb in a 1,000 lb of flyash.
BURNING A TON OF COAL IN CHINA IS AT ABOUT 50 – 100 TIMES WORSE THAN IN EUROPE AND THE US.
COAL COMBUSTION AND CARBON CAPTURE AN EXPENSIVE FALLACY
Some people have proposed to capture the carbon from fossil power plants and storing it underground, so-called CCS. The three main arguments against CCS are linked to each other.
The Energy Cost: Engineering the Future stated all of the CCS technologies currently available would require approximately 20 – 25% more coal or 10 – 15% more natural gas to be burned to produce the same amount of electricity.
The UK, together with the rest of Europe, is running low on indigenous primary energy supplies. There are only two rational responses to this serious problem:
– We must do all we can to boost sensible indigenous energy production, and
– We must do all we can to reduce energy consumption through energy efficiency and energy conservation strategies. CCS takes us in the opposite direction.
The energy costs include energy embedded in massive engineering at power stations, pumping stations, pipelines and burial sites. Coal is burned to create all that steel. And energy operating costs to capture, transport and compress CO2. This will add to the UK’s, and the rest of Europe’s energy import bills and dependency on imported fuel. The exact opposite of what we should be planning for. And these additional energy costs will be added directly to consumer electricity bills.
The Efficiency Cost: The energy efficiency of a large coal fired power station may be around 35%. That is 35% of the energy contained in the coal is converted to electricity and the remaining 65% is lost as waste heat. This waste heat is a serious problem for fossil fuel based generation and the sensible, traditional science and engineering approach would be to devise ways to address this problem. These strategies do of course exist in the form of combined heat and power generation where waste heat is used to heat homes or greenhouses and modern ultra supercritical coal fired power stations that can be 42% efficient. That 7% increase in efficiency may not seem a lot but it means the plant will consume 20% less coal.
CCS takes us in the exact opposite direction. A 25% energy penalty on a 35% energy efficient plant will reduce the overall thermal efficiency to 26%.
The Economic Cost: Mr. Allam of NET Power highlighted that a power plant with CCS costs 50% to 80% more to generate electricity than power plant without CCS. The CCS Cost Reduction Taskforce’s 2013 final report estimated that the first set of CCS projects may have costs in the range of £150–200 per megawatt hour (roughly three times as expensive as fossil fuel plant without CCS), a figure largely supported by industry. The main reason for this is the high energy consumption of powering the CCS equipment, especially the carbon capture stage of the process.
One would think that any MP, most of whom claim concern on high electricity prices, would read this and conclude that the proposals are unworkable. How can they reconcile in their own minds the concern for high electricity prices with the intention of government to subsidize measures that may result in a three-fold increase of these same prices they are so concerned about. And there are no benefits for consumers.
COAL COMBUSTION IN DEVELOPING NATIONS
The world consumption of coal grew from about 3.8 billion metric tonnes in 1980 to about 7.783 billion metric tonnes in 2011. China and the US consumed about 3.576 and 1.004 billion metric tons of coal in 2011, respectively. China consumption is increasing, US consumption is decreasing.
Because of a lack of high-efficiency AQC systems, a ton of coal combusted in China, India, Brazil, etc., is at least 50 times worse than in the US and Europe regarding particulate emissions/kWh, but about the same regarding CO2 emissions/kWh.
Currently, developing nations represent about 50 to 55 percent of the gross world product, a “dirty” percentage that is rapidly growing, whereas the “relatively clean” percentage of the developed world is decreasing.
Annual world energy production is about 20,000 TWh, of which the US 4,000 TWh, Germany 600 TWh, Vermont 6 TWh. At least 12,000 TWh is from “dirty” coal-burning by developing nations.
About 1,200 coal-fired power plants are planned worldwide, 75% in China and India. China’s CO2 emissions are increasing 8 to 9 %/yr, and are now about 50% greater than US emissions. China’s emissions are not expected to peak until about 2030.
Production – Self use, about 5% = Delivered to the grid.
Delivered to the grid – Trans. & Distr. losses, about 5% = Consumption.
China’s Coal Burning: China gets about 80% of its electricity and 70% its total energy from coal, much of it high-sulphur coal.
Coal CO2 emissions are about 2.15 lb/kWh x 1 kg/2.205 lb = 975 g/kWh at rated output. China is planning to build plants with more efficient coal plants. Here are some numbers of what is possible.
Plant Type………………………..Eff, %…………..g CO2/kWh
* Efficiencies of existing, older standard plants range from 30 – 35%.
Note: Combined cycle gas turbines, CCGTs, with an efficiency at rated output of 60%, Lower Heating Value, or about 54%, Higher Heating Value, would consume (3,413 Btu/kWh)/efficiency 0.60 = 5,688 Btu/kWh and emit 117 lb of CO2/(million Btu x 1 kWh/5,688 Btu) x 1 kg/2.205 lb = 302 g of CO2/kWh, much less than even the most efficient coal plants.
China has enacted emission standards for NEW coal plants, similar to the standards of Europe and the US, that became effective January 1, 2012. Coal plants of recent vintage have to comply with somewhat stricter standards by 2014. Coal plants of older vintage are “grandfathered”, i.e., need not comply.
Satellite surveillance likely will not detect a significant decrease in China’s particulate emissions for least two decades, as happened in the US after the 1970 Clean Air Act was enacted. Since 1970, as a percent of total energy production, the US coal energy percent decreased and the natural gas percentage increased which has materially reduced particulates and CO2 emissions from what they would have been.
Switching To Gas: The relative economic advantage of coal-based developing nations is low wages and low energy costs. They would not be switching to renewable energy, RE, because it would divert trillion-dollar investments from development over decades AND would increase their energy costs 2 to 3 times. As already-developed nations implement RE, they will become relatively less competitive vs. developing nations.
Because of advanced drilling techniques, developed and developing nations alike, would have available about a 300-year supply of low-cost, clean-burning natural gas. Those techniques could be used all over the world where there is shale.
The gas could be burned in 60% efficient, closed-cycle gas turbines, CCGTs, at a generation cost, including capital, O&M, etc., of about 6-7 c/kWh, less expensive than energy from NEW coal plants. The capital costs of CCGT plants would less than half of coal plants.
At rated output, CO2 emissions of a CCGT plant would be about 1/3 of a NEW coal plant. No RE can compete with this cost. Coal mines could shut down over time, the most expensive ones first. The net effect would be a major WORLDWIDE reduction in CO2 and particulate emissions.
SEA LEVEL RISE
The melting of glaciers, such as on mountains, and other land ice, such as on Greenland and the Antarctic, has raised sea levels.
– from 1870 to 1930, 60 years, the rise was 50 mm, or 0.83 mm/yr
– from 1930 to 1993, 63 years, the rise was 150 mm, or 2.38 mm/yr
– from 1993 to 2012, 19 years, the rise was 60 mm, or 3.17 mm/yr
At the latter rate, sea level rise will be about 88 yrs x 3.17 mm/yr = 279 mm = 279/304.8 = 0.92 feet by 2100. With an increasing rise rate, the sea level rise will likely be about 1.5-2.0 feet by 2100, and rising further. During weather events, such as Tropical Storm Sandy ($50 billion damage) and Hurricane Katrina ($146 billion damage), there are tide- and wind-driven water level surges which may temporarily raise water levels by 10-15 feet.
Note: The melting of sea ice (floating on water), such as at the North Pole, has almost no effect on raising the sea level.
Note: The top 1,000 feet of oceans are becoming warmer; the water expands and thereby adds to the sea level rise.
In recent decades, the sea level rise rate has increased due to increased particulate deposits on snow and ice surfaces, primarily from increased coal combustion by China, India, Brazil, etc. The particulates are also entrained in any Arctic precipitation. As the 24-hour summer sun melts the Arctic snow and ice, it becomes darker which accelerates the melting; an unstoppable positive feedback that will not abate until particulate deposits become minimal which will take many decades, if ever.
Arctic float-ice volume is better measure of Arctic warming than float-ice surface area. Satellites measured the minimum Arctic float-ice volume at 16,900 cubic kilometers in 1979, it was 3,600 in 2012, almost a 5-fold reduction during 33 years. At this rate, the Arctic float-ice will likely be almost entirely absent during the summer by about 2015-2016. This melting has and will significantly affect the weather and climate of the Northern Hemisphere. The CO2 ppMv influences this process at the margins.
The newly-exposed land and sea areas, instead of being highly reflective when covered with snow and ice, are highly absorbent of the sun’s energy, causing local increases in temperature, which in turn accelerate the melting; an unstoppable positive feedback.
Coastal studies experts: “For coastal management purposes, a sea level rise of 7 feet (2 meters) should be utilized for planning major infrastructure.”
By extrapolating the accelerating trend,
– Maine is preparing for a sea level rise of up to 2 meters by 2100,
– Delaware 1.5 m
– Louisiana 1 m
– California 1.4 m
– The Netherlands 0.6 – 1.2 m
– Southeastern Florida 0.6 m by 2060, at least 1 m by 2100.
THE PROSPECT OF THE NEW ORLEANS AREA BY 2100
The average elevation of New Orleans is currently 1-2 feet below sea level. Some areas are up to 20 feet above sea level at the base of the river levee in Uptown and others up to 7 feet below sea level in Eastern New Orleans.
Coastal erosion was accelerated by hurricane Katrina. By 2100, the coastline will pass New Orleans which will be, on average, at least 4 feet below sea level due to land subsidence plus sea level rise, i.e., entirely surrounded by the Gulf of Mexico, a la Venice. The city will need to be surrounded by a 40- to 60-feet tall levee system; currently, the top of the levee system at the Mississippi River side is 23 ft above sea level and at the Lake Pontchartrain side 17.5 ft.
About 2,000 square miles of coastal lands have been lost since 1900. An additional 5,000-6,000 square miles of coastal lands will be permanently under water due to rising sea levels and land subsidence by 2100.
A much larger area will be periodically flooded during hurricane events accompanied with wind- and tide-driven water surges, such as by hurricane Katrina.
DEALING WITH HIGHER WATER LEVELS
As infrastructures are usually built to last for at least 100 years, the most prudent approach for the effective use of limited resources would be:
– not to spend decades building expensive, massive waterworks to prevent flooding, except around high-value areas, such as Manhattan Island of New York City; the Dutch would have built a series of seawalls at least 100 years ago. Manhattan will need to do it. It will be expensive, about $15-$20 billion, but if the Dutch can afford it, so can the US. Just spend less on defense, education and healthcare per person, as the Dutch do.
– to build any new housing and other buildings, roads, etc., on grounds at least 20 feet higher than the present sea levels to provide a long-term margin of safety.
– in coastal areas and in land areas near river estuaries that would be permanently or periodically flooded, no new building should be allowed.
Note: some land areas, especially those subject to wind- and tide-driven water surges, that were thought to be safe, i.e., at least 20 feet above current sea levels, might erode at some time, and thus would not be suitable for resettlements.
– the newly-built houses and other buildings, roads, etc., should be arranged for the highest possible energy efficiency, i.e., minimal energy and other resource consumption per capita.
– areas with centuries of experience dealing with rising water levels, such as the Netherlands, would need to modify parts of their waterworks to avoid future flooding.
Measures to Reduce Development in Flood-Prone Areas: One way to encourage people to resettle from flood plains is to immediately prohibit new development in flood plains and start eliminating the subsidies for existing real estate in flood plains on a 5-year or 10-year schedule, such as:
– real estate mortgage interest and real estate tax deductions from taxable incomes
– real estate depreciation deductions from taxable incomes
– the $500,000 capital gains exclusion from taxable incomes
– prohibit private and government flood insurance
– prohibit private and government mortgages
– prohibit government funding for upgrading existing development; repair would still be allowed
These measures would depopulate the parts of Florida, the US East Coast and the Mexican Gulf that are too low-lying and that, by hindsight, should never have been developed. Those areas acted as natural barriers to flooding.
Any new development in those flood-prone areas should not be allowed. The funds saved by eliminating the subsidies should be used to resettle people and reclaim these areas for natural barriers to flooding.
Note: Most of the damage to the US East Coast due to Tropical Storm Sandy in 2012 was due to people building houses and other buildings on filled-in marsh lands and sand bars that are only a few feet above mean sea level; JFK airport is partially built on such land. That damage would have been avoided had the above measures been in effect. It is perverse to provide subsidies to rebuild in these areas. People, owners and renters, who were flooded by Sandy should be given a generous check for damage and relocation expenses,, i.e., “made whole”, and be told to move elsewhere. The debris, foundations, underground piping, wiring, etc., in the flooded areas should be removed, and the areas graded, etc., so they can be returned to Nature. It is beyond rational to rebuild, rebuild, rebuild, etc., mostly at government expense.
LEAST-COST REDUCTION OF MANMADE GW FACTORS
Because resources are limited, these measures should take precedence over expensive RE build-outs that would take decades to implement, produce expensive energy, but would be ineffective to slow the GW trend.
To limit manmade GW factors would be to:
– reduce CO2 emissions by means of increased energy efficiency.
– reduce energy and other resources consumption per capita.
– reduce the population to about 1.5 billion (the level in the late 1800s) from the projected 10 billion by 2050.
Based on hindsight, it can be concluded that already in 1865, certainly by the late 1800s, deforestation, pollution, overfishing, flora and fauna habitat destruction, etc., by less than 1.5 billion people were unsustainable, even with each person using relatively little resources compared to what each person uses at present.
The projected 10 billion people by 2050 will be spreading themselves around the world, taking over, dividing and diminishing more and more of the environment and the ecosystems and habitats of the fauna and flora; turning 4-lane roads into 8-lane roads, a la California; turning million people cities into multi-million people cities, a la China and India; each succeeding generation adding its damage to the prior damage.
An unavoidable environmental holocaust? A predictable outcome worth celebrating? Germany’s ENERGIEWENDE (turn towards RE) the answer? Is a worldwide environmental remediation and population control effort not at least 150 years overdue?
Example of Deforestation and “Reforestation”: In New England, after 80% of it was stripped of its old-growth trees by about 1865, much of the top soil, a thin layer on top of rocks in most places built up over about 9,000 years, eroded.
As a result, the new-growth trees that “reforested” less than 50% of New England can be only a pale copy of the old-growth trees. Acid-laden precipitation from Midwest coal plants has damaged the soil, sickened the trees, reduced their longevity and their CO2 absorbing capability.
New England’s forest biomass quantity prior to 1865 likely was about 5 times greater than at present and its CO2 absorbing capability likely was about 10 times greater than at present. New England has seen vastly greater additional manmade environmental destruction since 1865; highways and sprawling urban areas come to mind.
Proposals to burn biomass (wood) for New England’s thermal and electrical energy requirements is akin to scorced-earth warfare, given the present forest and soil conditions.
To remedy the situation would require a significant reduction of acid-laden precipitation AND the forests to be left undisturbed for several hundred years to restore top soil health and thickness.
If dead trees and branches were cut into woodchips that were spread evenly throughout the forest floor, the top soil restoration would be quickened. The thinking all this can be remediated by reducing CO2 emissions with RE build-outs is well beyond rational.
ENERGY EFFICIENCY BEFORE RENEWABLE ENERGY
As the required resources/capital are massive, the most cost-effective way is EE before RE. I am not saying “no RE”, just that it should be done after EE. The RE systems would be much less costly and of much lesser capacity AFTER EE.
It would be much wiser, and more economical, to shift subsidies away from expensive renewables, that produce just a little of expensive, variable, intermittent energy, towards increased EE. Most of those renewables would not be needed, if we use those funds for increased EE.
EE is the low-hanging fruit, has not scratched the surface, is by far the best approach, because it provides the quickest and biggest “bang for the buck”, AND it is invisible, AND it does not make noise, AND it does not destroy pristine ridge lines/upset mountain water runoffs, AND it would reduce CO2, NOx, SOx and particulates more effectively than renewables, AND it would slow electric rate increases, AND it would not require expensive electric grid build-outs, AND it would not require inefficiently-operated gas turbine balancing plants, AND it would slow fuel cost increases, AND it would slow depletion of fuel resources, AND it would create 3 times the jobs and reduce 3-5 times the Btus and CO2 per invested dollar than renewables, AND all the technologies are fully developed, AND it would end the subsidizing of renewables tax-shelters at the expense of rate payers, AND it would be more democratic/equitable, AND it would do all this without public resistance and controversy.
ADVERSITIES OF OUTSOURCING GOODS PRODUCTION, AND RE BUILD-OUTS
Outsourcing Goods Production: In the 1960s, business leaders in the US, Europe, Japan, etc., became eager to sidestep union labor rates and work rules and increasingly strict environmental rules. They expanded their production of goods in China, India, Brazil, etc., which responded by building hundreds of coal-fired power plants with minimal AQC systems.
Global Environmental Rules: As predicted, Northern Hemisphere air pollution, i.e., CO2, SOx, NOx and particulates, increased to such an extent that it accelerated the melting of snow- and ice-covered surfaces, mostly in the Arctic.
For decades, numerous meetings were held with developing nations to get them to agree to strict environmental rules. The meetings were futile, because business leaders did not want their governments to require China, India, Brazil, etc., to comply with strict environmental rules, because it would have increased production costs and reduced profits.
Whereas the US, Europe, Japan, etc., continued to tighten environmental rules, developing nations refused to comply and, in the end, were given a pass. This was a major strategic mistake that accelerated GW.
Adversities of Outsourcing: The lower-cost goods from China, India, Brazil, etc., caused:
– tens of millions of workers in the US, Europe, Japan, etc., to become uncompetitive and redundant.
– wealth and income to shift to the top 5% of households leading to more upscale consumption of imported goods and services, especially in the US.
To deal with the adversities of outsourcing, less-disciplined governments of less-competitive European nations excessively borrowed to maintain a government-debt-driven, Potemkin prosperity.
In the US, an-anything-goes financial sector, led by Wall Street, aided and abetted by a bought-and-paid-for Congress doing “constituent service”, did its part by hyping boom conditions that led to the 1987 real-estate collapse, the 2000 dot.com collapse and the 2008 real-estate collapse, which reduced the net worths and incomes of tens of millions of households, which led to the Great Recession.
To rescue the financial sector from its follies:
– the US Federal Reserve engaged in $3.025 trillion quantitative easing in 3 phases: QE I, $1.725 trillion, QE II, $0.6 trillion, to be followed by QE III, 0.7 trillion; creating money out of thin air and using it to:
* buy “assets”, i.e., real estate mortgage backed securities, MBOs, from financial entities that are choking on them
* loan it, at near-zero interest rates, to the federal government to finance its deficits (few other entities would)
* loan it, at near-zero interest rates, to financial sector firms to improve their balance sheets
– the federal government engaged in trillion-dollar deficit spending to finance several wars (Iraq I and II, Afghanistan) and to ameliorate the adversities of the Great Recession; currently, the US national debt is in excess of $16 trillion, increasing at about $1 trillion/yr. Those deficits likely will be taken care of by QE IV, QE V, etc.
Adversities of RE Build-Outs: The GW and climate change, CC, scare-mongering, business tactics of RE promoters, aimed at maintaining and increasing subsidies for expensive RE build-outs that produce expensive, variable, intermittent energy, would:
– further worsen the economic competitiveness of the US, Europe, Japan, etc., as the extra costs have been, and will be, rolled mostly into household electric rates.
– not reduce the Arctic warming caused by air pollution, because the coal-burning developing nations, including China, India, Brazil, etc., will continue to get a pass on environmental rules.
– cause significant additional destruction of the environment and the habitats of the fauna and flora than would increased EE.
– cost trillions of dollars more in captal outlays than would increased EE; capital that could be more profitably utilized.
– cost trillon-dollar government subsidies to project developers and financiers, plus trillion-dollar foregone tax revenues due to subsidies in the form of tax credits, such as the production tax credit, PTC, and income tax reductions for high-income households due to the special 5-year depreciation write-offs associated with RE build-outs.