Climate Change

From: McKinsey Sustainability

By: Rory Clune, Laura Corb, Will Glazener, Kimberly Henderson, Dickon Pinner, and Daan Walter

Date: May 5, 2022

Navigating America’s net-zero frontier: A guide for business leaders

With the United States’ announcement of targets to halve US greenhouse-gas (GHG) emissions by 2030 and reach net-zero emissions by 2050, the world’s largest economy (and second-largest emitter) has joined some 130 nations in its intention to act on climate change.1 Some 400 large US-based companies have also committed to net-zero targets of their own, many of which have set ambitious emissions reductions targets for 2030 or sooner.2 In our experience, few have yet turned those pledges into detailed plans for adjusting their business models to thrive in a net-zero economy.

Creating an effective business plan for the net-zero transition won’t be easy, for uncertainty surrounds the pace and scale at which this transition will progress in America and in other countries. That uncertainty has been compounded by the conflict in Ukraine, which has increased the world’s attention to energy security, creating both tailwinds and headwinds for the energy transition. In light of this uncertainty, US companies may wish to assess the business risks and opportunities and the socioeconomic impacts associated with the transition. We believe the companies that understand these factors can better position themselves for long-term success and positive impact. Those that delay action may miss out on growth prospects that should arise as institutions in America and elsewhere strive to eliminate GHG emissions in pursuit of national and corporate targets.

This article is intended as a guide to America’s net-zero transition. It examines four topics critical for business leaders as they shape strategies for this defining decade. First, we describe America’s starting point and trace a pathway that we modeled for achieving federal net-zero targets. Next, based on this pathway, we identify five areas in which climate solutions could offer enormous potential for both emissions abatement and economic growth through 2025: renewable power, electrification, operational efficiency, clean fuels, and carbon capture. We then examine several macro trends that business leaders should anticipate. Finally, we suggest how executives might define their company’s approach to the transition. Even if the transition plays out differently from what our scenario envisions, it appears that a time of climate-focused innovation, investment, and change has arrived—and that leaders would do well to prepare for it. (continue reading)

Navigating America’s net-zero frontier: A guide for business leaders

Definition of uncertain (Merriam-Webster)

1a : not known beyond doubt : dubious an uncertain claim
b : not having certain knowledge : doubtful remains uncertain about her plans
c : not clearly identified or defined a fire of uncertain origin
2 : not constant : variable, fitful an uncertain breeze
3 : indefinite, indeterminate the time of departure is uncertain
4 : not certain to occur : problematical his success was uncertain
5 : not reliable : untrustworthy an uncertain ally

We live with uncertainty and make the best decisions we can based on the uncertain information available. Weather and climate are not constant, nor is our knowledge regarding what they are and what they will be in the future. Many factors regarding climate are not known beyond doubt, such as climate sensitivity and feedback. Many weather and climate events are problematical and their timing indefinite, including ENSO (El Niño-Southern Oscillation) events, PDO (Pacific decadal oscillation) and AMO (Atlantic Multidecadal Oscillation) shifts, tropical cyclone timing, frequency and intensity, tornadoes, droughts and floods. The origin of wildfires is frequently unidentified. Forecasts of future weather and climate events are not reliable. The existence of multiple but differing near-surface temperature records, sea level rise measurements and climate model projections are all examples of uncertainty regarding climate and climate change.

The uncertainty regarding weather and climate leads to uncertainty regarding the performance of systems dependent on weather, such as wind and solar electric generation. History provides some basis for estimating typical wind velocities and solar insolation levels in specific locations. However, sufficient uncertainty remains to require the inclusion of some redundant generating and storage capacity to deal with events beyond previous experience. The recent “wind drought” and extended period of below normal solar insolation which affected the UK and Western Europe are examples of such events. Daily variations in wind speed and solar insolation are reasonably predictable, but the accuracy of the predictions declines over longer periods.

The goals of electrifying all energy end uses and supplying all of them with a renewable electric generation and storage infrastructure add additional uncertainty regarding the pace of the transition and the relative efficiencies of the fossil and electric end uses. There are also end uses, such as the production of iron and steel and the calcining of cement, for which there are currently no non-fossil alternatives and for which the potential availability of alternatives is unknown.

The uncertainties regarding weather and its impact on the operation of weather-dependent electric generating systems greatly complicate the design and operation of a renewable plus storage electric grid. The frequency and duration of low/no wind and solar events affect the design capacity of the generation system, the relative design capacity of wind and solar generation in the system, and the capacity and discharge rates of the storage.

The mix of these system components would vary considerably from region to region within the US and around the globe as a function of wind and solar availability. The design of the storage systems will be heavily dependent upon the mix of wind and solar and upon the likely frequency and duration of low/no wind and solar events.

From: Gatestone Institute

By: Francis Menton

Date: April 25, 2022

A Mostly Wind- and Solar-Powered U.S. Economy Is a Dangerous Fantasy

When President Biden and other advocates of wind and solar generation speak, they appear to believe that the challenge posed is just a matter of currently having too much fossil fuel generation and not enough wind and solar; and therefore, accomplishing the transition to "net zero" will be a simple matter of building sufficient wind and solar facilities and having those facilities replace the current ones that use the fossil fuels.

They are completely wrong about that.

The proposed transition to "net zero" via wind and solar power is not only not easy, but is a total fantasy. It likely cannot occur at all without dramatically undermining our economy, lifestyle and security, and it certainly cannot occur at anything remotely approaching reasonable cost. At some point, the ongoing forced transition... will crash and burn.

[I]t doesn't matter whether you build a million wind turbines and solar panels, or a billion, or a trillion. On a calm night, they will still produce nothing, and will require full back-up from some other source.

If you propose a predominantly wind/solar electricity system, where fossil fuel back-up is banned, you must, repeat must, address the question of energy storage. Without fossil fuel back-up, and with nuclear and hydro constrained, storage is the only remaining option. How much will be needed? How much will it cost? How long will the energy need to remain in storage before it is used?(continue reading)

A Mostly Wind- and Solar-Powered U.S. Economy Is a Dangerous Fantasy

Climate skeptics question assertions and projections which are not based on, or are in conflict with, observations and data. These are the common bases for skepticism regarding "adjusted” near-surface temperature measurements, “adjusted” sea surface temperature measurements, conflicting sea level rise measurements and multiple unverified and unvalidated climate models. They are also the common bases for skepticism regarding assertions of a “climate crisis”, “climate emergency” or “existential threat”.

Climate alarmists dismiss this skepticism as “climate denial” or “climate change denial", or label the skeptics as “anti-science“. However, skepticism is essential to the advancement of science and human understanding.

Climate alarmists claim to be able to detect the influence of anthropogenic CO2 emissions in a broad variety of weather and climate events, including: hurricane frequency, intensity and speed; tornado frequency and intensity; heat and cold waves; drought frequency and severity; and, flooding frequency and severity. They project that hurricanes will become more frequent and stronger and that they will advance more slowly, increasing precipitation in their paths. They also project that tornadoes will become more frequent and stronger and that tornado swarms will become more common. These assertions of detection and projections are typically the result of model-based attribution studies and climate model projections.

Let us suspend skepticism and consider the implications of these assertions for a renewable plus storage US energy system. Roger Pielke, Jr. and Bjorn Lomborg, among others, have determined that the increasing costs of damage caused by extreme weather events are largely the result of increased investments in infrastructure in areas historically prone to extreme weather and to the increasing value of those infrastructure investments with increasing GDP.

It is uncommon for energy generation and production infrastructure to be severely damaged by extreme weather events, though damage to electric transmission and distribution infrastructure is far more common. This is, in part, the result of the relatively limited number of generation and production facilities and of the structural design of these facilities.

A US renewable plus storage energy system composed of a mix of on-shore and off-shore wind and ground-mounted solar photovoltaic collector panels would dramatically increase the number of electric generation sites and the area occupied by those generation sites, significantly increasing the exposure of energy generation infrastructure to extreme weather events. The renewable plus storage energy system would also require major transmission infrastructure expansion to connect the numerous, dispersed generators to the existing electric grid.

Professor Michael Mann has suggested that the Saffir-Simpson Scale used to categorize hurricane strength be expanded from the current 5 categories to 6 categories in anticipation of stronger future hurricanes resulting from projected climate change. The Biden Administration has announced its intent to incentivize the installation of 30 GW of offshore wind turbine generating capacity off the East and Gulf coasts of the US. This raises the question of the ability of these offshore wind turbines to withstand the impact of Category 3-5, no less Category 6, hurricanes with sustained wind speeds of up to 200 miles per hour.

There have also been suggestions that tornadoes of greater than F5 strength might be in our climate change future. However, the Fujita scale already extends to F12, though it is generally accepted that virtually nothing is left standing in the path of an F5 tornado with wind speeds of 260 – 318 miles per hour. A combination of increased generation infrastructure occupied land area and increased tornado frequency and intensity would likely increase the frequency and extent of damage to renewable generation infrastructure.

By: PragerU

From: Master Resource

By: Robert Bradley Jr.

Date: April 26, 2022

“A Promise Kept: Biden’s War on American Energy”

Some policy statements and summaries are valuable for the historical record. The Republican review below highlighting Biden oil policies relative to gasoline prices is worth studying and memorializing.

Presidential politics and tone are important to the investment health of consumer-driven, taxpayer-neutral energies. Biden campaigned against the very energies the America needs, including those of motorists and other consumers of transportation fuel. Ditto for natural gas. Ditto for coal in the generation of electricity.

It is past time for the oil, gas, and coal industries to wise up and stop trying to appease the radical left. It is past time for Democrats to become the party of the working class. And it is past time for Republicans to become more consistent and forceful against government favors to any energy (ethanol and nuclear included) and any technology (carbon capture and storage) that a business lobby wants. (continue reading)

“A Promise Kept: Biden’s War on American Energy”

Simple Definition of fact

: something that truly exists or happens
: something that has actual existence
: a true piece of information

Simple Definition of fancy

: to believe mistakenly or without evidence
: to believe without being certain

Source: Merriam-Webster's Learner's Dictionary

I have described climate science as the science of data that aren’t and models that don’t. Climate science is a science of few “facts” and many “fancies”. Much climate “data”, specifically regarding global average temperature anomalies, is not really data because the actual temperature readings have been “adjusted”, for a variety of reasons, and therefore are not “something that truly exists”. Rather, they are estimates of what might have truly existed if the data had been collected timely from properly selected, calibrated, sited, installed and maintained instruments.

It is certainly a “fact” that the globe has warmed since the trough of the Little Ice Age. However, the degree of warming which has occurred is an estimate, because of the non-uniformity of instrument coverage, the “adjustments” made to the instrument readings and changes which have occurred in the immediate surroundings of the instrument locations. Therefore, the reported temperature anomalies are “fancies”, especially considering the precision with which the anomalies are reported.

It is certainly a “fact” that sea level has risen, at a relatively continuous rate since the trough of the Little Ice Age. However, the rate of sea level rise reported from satellite observations is a “fancy” because the measurements have been taken by a series of different satellites using different instruments. The measurements taken by these different satellite instruments do not agree with each other, nor do they agree with the measurements taken by the tide gauges which produced the much longer historical record. The consensed climate science community might believe that the satellite measurements, or at least one set of the satellite measurements, are accurate but they cannot be certain because of the discrepancies.

The outputs of the climate science models are “fancies”, fundamentally because there are multiple models which produce differing results. It is not certain whether any of the model outputs is “a true piece of information”. It is a “fact” that the model outputs have not accurately projected the temperature anomaly estimates developed from the near-surface temperature measurements or from the satellite observations.

The sensitivity of the climate to the addition of ‘greenhouse” gases to the atmosphere is a “fancy”, in that it is expressed as a range of values, which is a clear illustration of uncertainty; and, because there is uncertainty regarding whether the actual sensitivity value lies within the range of values used. Feedback within the atmosphere are also “fancies”, since it is uncertain whether feedback is positive or negative, no less its actual magnitude.
 
Finally, observations of weather events such as hurricanes, tornadoes, floods and droughts are facts. However, attribution of some aspect of the characteristics of these weather events, using unverified and unvalidated models, are “fancies”. There is no clear evidence of a climate change contribution to the characteristics of the weather events, their frequency or their duration.

It has become common to portray climate change “fancies” as “facts”, even in the absence of evidence and certainty. This constitutes an excess of hubris and an absence of humility.

By: PragerU

From: The Global Warming Policy Foundation

By: Ole Humlum

Date: April 2022

The State of the Climate 2021

General overview 2021

This report has its main focus on observations and not on the output of numerical models, with the exception of Figure 39 (see p. 38). References and data sources are listed at the end of the report.

Air temperatures

Air temperatures measured near the planet’s surface (surface air temperatures) are at the centre of many climate discussions, but the significance of any short-term warming or cooling should not be overstated. Whenever the Earth experiences warm El Niño or cold La Niña episodes, major heat exchanges take place between the Pacific Ocean and the atmosphere above, eventually showing up as a signal in the global air temperature. However, such heat exchanges may chiefly reflect redistribution of energy between ocean and atmosphere, and not a change in the heat content of the atmosphere–ocean system. Evaluating the dynamics of ocean temperatures is therefore just as important as evaluating changes in surface air temperatures.

Considering surface air temperature records since the 19th century, 2021 was a warm year, but cooler than most years since 2016. A moderate La Niña episode played out during 2021, underlining the importance of ocean–atmosphere exchanges.

Many Arctic regions experienced record high air temperatures in 2016, but since then, including in 2021, conditions have generally moved toward somewhat cooler conditions. The temperature peak in high northern latitudes in 2016 may have been affected by ocean heat released from the Pacific Ocean during the strong 2015–16 El Niño and subsequently transported towards the Arctic region. This underscores how air temperatures may be affected, not only by variations in local conditions, but also by variations playing out in geographically remote regions.

Many figures in this report focus on the period since 1979 – the satellite era – when access to a wide range of observations with nearly global coverage, including temperature, became commonplace. These data provide a detailed view into temperature changes over time at different altitudes in the atmosphere. Among other phenomena, these observations reveal that a Stratospheric temperature plateau has prevailed since 1995.

Since 1979, lower Troposphere temperatures have increased over both land and oceans, but most clearly over the land. The most straightforward explanation for this is that much of the warming is caused by solar insolation, but there may be several secondary reasons, such as changes in cloud cover and land use.

Oceans ... (continue reading)

The State of the Climate 2021

Modeling has an uncertain reputation in climate science. However, the climate models are the purported underlying cause of the political concern regarding climate change and the “global” efforts to fundamentally change the global energy economy to avoid the “calamity” projected by the climate models.

The proposed changes to the global energy economy include the elimination of the use of fossil fuels as energy sources and their replacement with a combination of renewable energy generation and energy storage.  The proposed “deep decarbonization” would shift all current fossil fuel energy end uses to electric end-use vehicles, appliances and processes. This transition would approximately quadruple the current demand and consumption of electricity in the US economy.

It would be difficult, but extremely useful, to model this transition to determine the types and quantities of renewable generators and storage systems necessary to assure a reliable electric grid which would provide the most economical electric service for this greatly expanded demand and consumption scenario.

Ideally, the model would be national in scope. It would take into account the varying availability of each type of renewable resource in each region of the country, varying regional load patterns and historical regional weather conditions. Such a model would be essential to developing a regional demonstration of a renewable plus storage grid and could be developed initially to support that demonstration and then extended to national scope.

Critical historical weather factors for this model would include solar insolation, wind intensity, duration and timing, seasonal differences in solar and wind availability and the duration of low/no solar and wind periods. This information would be used to calculate the real capacity of the renewable generators under these conditions. It would also be used to calculate the frequency, rate and duration of transfers of electricity to and from storage and the additional generating capacity required to recharge storage under these operating conditions.

The model would initially be subject to significant uncertainty regarding storage, since the long-duration storage required to respond to multi-day and seasonal variations in renewable generator output are not currently available commercially, so their cost and their performance over the expected range of operating conditions are unknown. Experience with 4-hour storage is also quite limited. The range of expected storage operating conditions will also affect the in and out losses attributable to the storage system itself and to the generator DC to storage DC voltage conversion and the storage DC to grid voltage AC inversion.
The model would also be continually subject to uncertainty regarding the rate of growth of overall energy demand and consumption in the economy, as well as the rate of conversion of fossil fuel end-uses to electric end uses and the resulting increase in electricity demand and consumption.

The generation and storage design for the proposed demonstration program would be based on the model of the demonstration zone. Analysis of the data from the proposed demonstration program would permit the model to be adjusted based on the performance of the demonstration zone infrastructure.

The development and testing of this model are far more important than the use of climate models to generate “scary scenarios” of potential future devastation.

By: ClimateCraze

From: Watts Up With That

By: Charles Blaisdell PhD ChE

Date: April 13, 2022

Where have all the Clouds gone and why care?

The earth’s cloud cover has long been an important puzzle in climate change.  Cloud cover has many types and varies significantly from year to year.  Ground records of global cloud cover over 40 years have shown a 0.41%/decade decrease in cloud cover. (A 37-year European only study found a 1.4%/decade decrease).  In the last 20 years, Dübal and Vahrenholt CERES satellite has data that confirmed the ground observations of cloud cover decrease and a correlation with earth’s net incoming energy flux, albedo, and earth’s temperature rise.  Albedo is derived from the Latin word for white, a high albedo, 1.0, is totally reflective of sun light and a low albedo, 0.0, is totally absorbent, with albedo the lower the hotter.  These few pieces of data beg some questions.   When did cloud cover start to decrease?  Is it cyclic?  How much of the of the observed global warming, GW, can be attributed to cloud cover reduction?  What is causing it?  Will the decrease stop?  And, why should I care?  Let’s start with why should I care, every 1% reduction in cloud cover could account for 1.6 W/m^2 (about 0.8’C) increase in earth’s net incoming energy flux – a significant part of all the observed GW.  If this decrease started a 100 years ago and the current decrease is 0.4%/decade the total decrease over that time could be 2% or 3.2 W/m^2 (estimated 1.6’C GW) – more than the observed 2.2 W/m^2 (1.1’C GW).  Sumerville and Gautier in 1995 summarized that if the cloudiness of the earth decrease it would have a much greater effect on GW than doubling the CO2.  In 1995 no data existed that suggested the cloud cover or relative humidity was changing over time.  That is no longer true. (continue reading)

Where have all the Clouds gone and why care?

The wind and solar generation systems installed in the US have been installed in the most favorable locations available, for obvious reasons. However, as wind and solar generation are expanded toward a renewable plus storage generation infrastructure and electric demand increases as the result of electrification of transportation, residential, commercial and industrial appliances and equipment, wind and solar installations will have to be extended into less favorable locations.

US EIA Electric Power Monthly reports the annual average capacity factor of US wind installations as 35.3%, with capacity factors ranging from 28.2% - 41.1% seasonally. The annual average solar photovoltaic capacity factor is reported as 24.2%, with capacity factors ranging from 14.9% – 33.3% seasonally. These capacity factors would be expected to decrease somewhat as installations expanded into less favorable locations. However, capacity factors for offshore wind installations are expected to be somewhat higher than for onshore wind, in the range from 40-50%.

Solar installations in the northern tier of the US would be expected to have lower capacity factors during the Winter as the result of the lower sun angle and snow accumulations on the collector surfaces. Wind turbines operating in colder climates would require heating of the blades to avoid snow and ice accumulations, which would impose parasitic power consumption on the turbine generating capacity.

However, the greatest expected impact on renewable generation capacity factors would likely be the need to overbuild generation to have excess capacity available to recharge storage when storage replaces fossil generation as grid support when renewable generation fluctuates and during periods of low/no wind and solar availability. Significant renewable generation capacity would be in surplus during periods of good wind and solar availability when storage is fully charged.

The analysis of the need for storage is somewhat simpler for solar than for wind. On a clear day, solar collectors might generate at rated capacity for as long as 8 hours. However, they will predictably generate no electricity for the remaining 16 hours of the day. Therefore, any loads they serve would have to be served from surplus wind availability or from storage. Some solar generators are installing 4-hour storage to serve the daily peak in the late afternoon, after the solar system stops generating. However, that storage capacity must be recharged from excess capacity during the 8-hour solar generating day.

Wind generation is less predictable throughout the day and its fluctuations and interruptions must be met from storage, which must also be recharged from excess capacity during the day.

The increased investment resulting from generation overbuilding and the requirement to provide short and intermediate duration storage to smooth fluctuations in renewable generation output and long-duration storage to support the grid during periods of low/no wind and solar availability will also substantially increase the cost of the renewable plus storage grid. However, these additional costs are unavoidable if the grid is to be stable and reliable and not subject to catastrophic failure. Renewable generation developers have been able to ignore these issues in the mixed renewable and fossil grid, but will be unable to do so going forward.

From: Ventura Photonics

By: Roy Clark

Date: February 20, 2022

REJECT AR6

The Sixth IPCC Climate Assessment Report (AR6) should be rejected outright because it is based on the use of fraudulent climate models. This fraud comes from the underlying assumption of radiative forcing in an equilibrium climate used to construct the models. Such models are fraudulent by definition, before a single line of computer code is written. Climate science has now degenerated past scientific dogma into the quasi-religious ‘Imperial Cult of the Global Warming Apocalypse’. Scientific reason has been replaced by blind advocacy. There is no ‘climate crisis’. Eisenhower’s warning about the corruption of science by government funding has come true. The entire multi-trillion dollar Ponzi or pyramid scheme built on these fraudulent modeling results needs to be shut down and those responsible should face the legal consequences of their activities.

SUMMARY

The recently published draft of the latest UN Intergovernmental Panel on Climate Change (IPCC) Report, Climate Change 2021: The Physical Science Basis, [IPCC, 2021] the contribution of Working Group 1 to the Sixth IPCC Climate Assessment (AR6) should be rejected outright because the report is based on the results from fraudulent climate models. This fraud comes from the underlying assumption of radiative forcing in an equilibrium average climate used to construct the climate models. These models are fraudulent by definition before any computer code is even written. AR6 is a continuation of the climate modeling fraud that started with the invalid assumptions that were made when the first computer climate models were developed in the 1960s. All of the equilibrium climate model results used by the IPCC since it was established in 1988 are fraudulent.

There are at least three separate parts to this fraud. First there are the invalid climate equilibrium and related assumptions that originated in the nineteenth century. These led to melodramatic prophecies of the global warming apocalypse and became such a good source of research funding that the scientific process of hypothesis and discovery collapsed. Second, there was institutional fraud related to ‘mission creep’ within various government agencies. For example, NASA was established to put a man on the moon. There was no provision to shut it down after that mission was accomplished. Climate modeling provided alternative employment for some of the NASA ‘scientists’ with nothing else to do. The climate fraud was firmly established at NASA by 1981. Third, there was a deliberate decision by various outside interests, including environmentalists and politicians to exploit the climate apocalypse to further their own causes. There was no single person or event that created the climate fraud. There was a gradual transition from the invalid hypothesis of an equilibrium average climate to the massive multi-trillion dollar pyramid or Ponzi scheme that we have today. (continue reading)

REJECT AR6

The electric utility grid requires instantaneous balancing of demand and supply. Historically, most fluctuations on the grid were the result of changes in customer demand. However, as intermittent renewable sources of generation are added to the grid, changes in the output of wind and solar generation sources increase the complexity of grid balancing. A recent report by Elexon regarding grid balancing in the UK illustrates the rapid increase of grid balancing costs as the intermittent renewable fraction of generation increases. The report suggests that this trend will continue as the percentage of intermittent generation on the grid increases.

The principal source of grid balancing generation in the UK is natural gas combined-cycle generators, as it is in the US. Battery storage is currently a minor source, though it is planned to grow considerably. However, it is critical that battery storage growth exceeds the rate of reduction of capacity of the other sources of grid balancing generation, particularly natural gas generation. This is especially important because of the anticipated growth of electric demand resulting from the electrification of transportation, residential, commercial and industrial energy consumption.

As the transition from fossil generation to renewable generation proceeds, the contemporaneous transition from fossil grid balancing to storage grid balancing would increase the renewable generation capacity required to support the grid. Storage would support the grid during periods of low/no wind and solar generation, but would require the availability of renewable generating capacity in excess of the contemporaneous grid demand to recharge the storage batteries so that they are ready for the next requirement for grid balancing.

The excess generating capacity required would be a function of the duration of the grid balancing demand on storage resources and the period over which storage must be recharged. For example, the “wind drought” which affected the UK and parts of Europe in the fall of 2021 lasted for approximately 10 days. In that case, the grid balancing was accomplished with fossil generation in the UK and nuclear-generated electricity imported from France. However, in a renewable plus storage grid, the balancing generation previously provided by fossil generation would have to be replaced by withdrawals from storage. A requirement to replace the electricity drawn from storage in such a 10-day period over the following 10 days would require a doubling of renewable generating capacity, half to serve the contemporaneous demand of the grid and the other half to recharge storage, assuming no further demands on storage for grid balancing over that period.

It has been common in the US grid to maintain a 20% capacity reserve margin relative to peak demand, should one or more generators need to be taken offline for maintenance or repairs. In a renewables plus storage grid, both the renewable generation and the storage system would have to include such a capacity reserve margin. A requirement to function through a 10-day period of low/no wind and solar and to recharge storage over the succeeding 10-day period, with a 20% capacity reserve margin, would require renewable generating capacity approximately 2.4 times peak demand on the grid.