The best of all possible energy worlds would be one in which energy is non-polluting, reliable and inexpensive. Unfortunately, nobody knows how to achieve all three goals simultaneously.

Some advocates of renewable energy would have you believe that wind and solar are a sufficient basis for that world. They are wrong. Wind and solar are non-polluting, but they are not reliable, and while their direct costs have fallen in the past decade, each still imposes substantial costs on the overall electrical system.

These costs come in several forms. The ones discussed here are 1) the necessity for overbuilding wind and solar energy facilities, 2) the need for large amounts of storage and/or backup energy production and 3) increased transmission costs.

New York cannot escape these energy realities as it transitions to heavier reliance on emissions-free, but unreliable, wind and solar power.


New York’s Climate Leadership and Community Protection Act (CLCPA) requires dramatic and fundamental changes to the state’s supply of electricity. By 2030, only eight years from now, 70 percent of the state’s electricity supply would come from renewable sources under CLCPA, more than double the current 31 percent.

By 2040, a mere 18 years away, 100 percent of the electric supply is required to come from zero-emissions sources, meaning hydroelectric, wind, solar and perhaps nuclear under CLCPA goals.

Currently, hydroelectric provides approximately 23 percent of the state’s electricity supply. That is not likely to increase substantially. Biomass (burned plant materials) is a very small percentage of renewable energy and unlikely to become significant. Getting to 70 percent renewables will mean getting at least 45 percent of electricity from wind and solar power.

Getting to the CLCPA goal of 100 percent zero-emissions electricity gives us the same result. Hydro and nuclear (which is also emissions-free) together account for approximately 46 percent of the state’s electricity supply. A further 10 percent of our electricity will come from some as-yet-undetermined source, according to the New York Independent System Operator (NYISO). That adds up to 55 percent. So even if the state’s nuclear plants are relicensed – which isn’t guaranteed – that again leaves approximately 45 percent of New York’s electricity to be supplied by wind and solar power.

If New York’s nuclear plants are not relicensed in the coming decades, then wind and solar will have to supply about 67 percent of New York’s electricity.

This level of renewable energy has rarely been achieved in any sizeable region, and then only briefly.[i] The U.S. leader in renewable energy is Iowa, at just under 58 percent.[ii] But that is mostly wind, in a prairie state where the wind tends to blow steadily. And the remainder of Iowa’s power, as well as the backup for its windpower during wind lulls, is produced by coal and natural gas.

New York’s ambitious goals for renewable power can be achieved, but – like Iowa – only with dispatchable backup power.

Unfortunately, this is not yet widely known, and many people mistakenly think we can not only move easily to wind and solar, but that they will be cheaper than our current sources of electricity. The costs are not easy to estimate, but with a look at the challenges it is easy to explain why reliability and low cost are not achievable.

An Overview of the Cost of Shifting to Renewables

No cost analysis has yet been provided for New York’s transition to reliance on wind and solar energy. This is a remarkable failure by the state’s Climate Action Council, which is responsible for guiding the transition, and which has hired consultants who ought to have provided the public with this information.

But numerous other studies have identified significant costs from shifting to renewables, including:

  • California’s push toward increasing shares of wind and solar in its electricity mix caused retail electricity prices to increase faster than the average price increase across the U.S. and to become 50 percent higher than the U.S. average in 2016.[iii]
  • A study by IHS Markit shows that a less diverse electricity resource base could raise retail electricity prices by as much as 27 percent.[iv]
  • Scholars from Tufts University’s Global Development and Environment Institute note that “renewable energy sources have low capacity factors and are less consistent than fossil fuels, which increases cost.”[v]
  • A University of Chicago study showed that states that passed renewable portfolio standards to promote renewable energy production had electricity prices that were 11 percent higher after seven years and 17 percent higher after 12 years.[vi]

The most optimistic cost studies assert only moderate price increases, but those models are based on a non-existent nation-wide grid that can readily transfer solar and wind from where it is being produced (the Desert Southwest and the Great Plains, for example) to where it is most needed.

The continental scope of such plans is necessary to achieve such optimistic predictions. No state-level study has yet found support for a low-cost transition.

There is one overriding reason why shifting to large amounts of wind and solar power is challenging and costly: the unreliability of these variable resources. Uncontrollable meteorological conditions mean the sun doesn’t always shine and the wind doesn’t always blow —and on occasion, neither is happening.

This is a critical flaw. Supply and demand in the electrical grid must be balanced at all times. Low levels of wind and solar are easily managed when they are a small portion of total supply to the electrical grid. But as the amount of these variable resources in the grid increase, the challenge of managing supply and demand also increases. As noted above, this unreliability has multiple consequences on system costs, including, the necessity of:

  1. Overbuilding wind and solar resources;
  2. Building more transmission lines; and
  3. Backup power or storage.

1. The Necessity of Overbuilding Wind and Solar Resources

Overbuilding means building more units of a resource than its nameplate capacity would indicate are necessary. Nameplate capacity is how much power a facility can produce at maximum output, while capacity factor is how much energy is produced on average as a proportion of potential annual production.

For example, a nuclear plant may have a nameplate capacity of one-gigawatt, meaning it can produce up to that much power at a time. If it ran at 100 percent capacity for a year, it would produce 8,760 gigawatt hours of electricity (there are 8,760 hours in a year). But with a capacity factor of 90 percent, it would average an annual production of 7,884 gigawatt hours.

Natural gas plants are comparable to nuclear plants in their potential capacity factor, so they can produce as much electricity for a facility of equal capacity .

But the capacity factor for offshore wind is 44 percent, so a wind facility with a nameplate rating of one-gigawatt would produce around 3,854 gigawatt hours of energy annually. Therefore, two gigawatts of offshore wind capacity would be required to replace a one-gigawatt nuclear or natural gas plant.

Solar in New York is even less efficient, with a capacity factor of 12.6 percent.[vii] So, a one-gigawatt photovoltaic solar array would produce 1,104 gigawatt hours annually. In other words, it would take more than seven gigawatts of nameplate solar capacity to equal the one-gigawatt nuclear or natural gas plant.

The number of one-gigawatt facilities of various types that would be needed to meet New York’s current annual energy consumption solely from that source is shown in Figure 1, which graphically illustrates the amount of overbuilding required as we increase our reliance on wind and solar power.

With demand expected to more than double due to growth in electric car sales and increased electrification of home heating, this disparity would grow even more.


2. The Need for Backup Power or Storage

But the problem of unreliability is not solved simply by overbuilding. If the sun was always shining somewhere in the Empire State, or the wind always blowing, then we could theoretically overbuild – whatever the cost – and just shift the power from wherever it is being produced at any given time to where it is needed.

But over a geographical territory the size of New York, the sun isn’t always shining, the wind isn’t always blowing, and sometimes neither is happening.

Solar unreliability comes both from heavy cloud cover and nightfall. Particularly during winter, the sun sets in late afternoon, causing solar power to decline to zero just as demand begins to rise to its daily peak as people return home from work.

Wind has a higher capacity factor than solar, but wind lulls are not uncommon. On March 3, 2021, for example, a wind lull in Great Britain caused wind power to fall to less than one percent of its normal output.[viii]

Wind in New York is both seasonally variable (figure 2[ix]) and subject to protracted lulls (figure 3[x]). Peak wind production in New York is currently over 1,600 megawatts, but average monthly production at its best is less than half that, and during a six-day lull in January 2021 it ranged from zero to 400 megawatts.



Periods of combined low wind and solar can occur, too. Germans have dubbed these conditions “Dunkelflaute” (meaning a dark wind lull). During such a period neither wind nor solar will produce substantial amounts of electricity.

One highly optimistic report on the future of clean energy in the United States nonetheless identifies, during its seven-year study period, a minimum period of combined wind and solar energy production that was only 6 percent of rated equipment capacity.[xi]

Nobody has yet quantified the frequency of such events in New York, but the state’s Climate Action Council concedes that “there are . . . many weeks in the year – especially during the winter – in which the contributions from renewables and existing clean firm resources are not enough to meet demand.”[xii]

And as if to reinforce that risk, NYISO reported many days of almost no solar and wind production in New York during January and February of 2022.[xiii]

All this requires that we have backup sources of electricity, which can be achieved with energy storage or energy production.

Energy Storage – High Cost, Limited Potential

There are multiple potential sources of energy storage. Notable ones include pumped hydroelectric, batteries and hydrogen. But because energy storage requires “charging up,” it always consumes more electricity than it injects back into the system, which increases the overall need for electricity production.[xiv]

Pumped Hydroelectric

New York already uses some pumped hydropower for energy storage. Water is pumped uphill into a reservoir, usually at night when energy is inexpensive, then released during periods of peak demand during the day.

Geographically, there are many places where pumped hydropower could be located in New York, but politically it is challenging to do so because it often requires creating reservoirs in relatively pristine natural areas.

Pumped hydro has an advantage over wind and solar in that it is dispatchable on demand. However, it is limited in duration, being very useful for only a few hours per day, but not sufficient for multi-day demand. In addition, as with all types of storage, there must be a reliable source of energy available during periods of low demand in order to replenish the reservoirs.


New York’s CLCP originally called for 3,000 megawatts of battery storage by 2030. Governor Hochul doubled that target to 6,000 megawatts earlier this year.[xv]

Batteries also provide dispatchable power, so they can provide at least two substantial benefits to the electrical grid. First, they can help manage grid stability because they can respond very quickly to drops in voltage or frequency. Second, they can potentially – given enough battery power – help meet peak demand.

But batteries have several drawbacks as well.

First, they are very expensive. Estimates from California show the cost to be between $1,096[xvi] and $1,612[xvii] per megawatt hour, more than twenty times the cost of natural gas.

It is possible that batteries will decline in cost in coming decades as technologies become perfected, but the costs will need to come down by at least 90 percent to make them cost-competitive with fossil fuels.[xviii]

Further complicating the matter is the potential for increased competition for the raw materials for batteries, as both cars and electrical grids require ever more of them, not just in the U.S. but globally. Meanwhile, many of those raw materials are available only in a few countries, and currently most refining is controlled by China. All of this makes any prediction about the price of batteries in the coming decades wholly speculative.

Second, what really matters with batteries is not simply the power available, but how long the batteries can emit that amount of power before being drained. Currently that is only a few hours, making batteries potentially useful, as noted, for meeting peak demand, but not for meeting multi-day demand.

The current target goal is the 100-hour battery, which is just over four days' worth of electrical charge. But periods of low wind and sun, particularly in winter, can last longer than that.

Finally, as with pumped hydro, excess electrical power is necessary to recharge the batteries. During normal times this may happen at night, when electricity demand is low. But a prolonged Dunkelflaute could drain batteries and prevent their regeneration in time to meet people’s needs.

In summary, batteries will play a role in the green energy economy, but there is little prospect of having full and reliable battery backup, much less at low cost.


Hydrogen is often discussed as though it is an energy source, but is more accurately described as a form of energy storage. Hydrogen has to be produced, and as with all energy storage systems, there is energy loss in the process.

The advantage of hydrogen is that it burns cleanly, and if produced from water using emissions-free energy, the production process is also clean.

However, hydrogen is another technology that is still developing and very expensive. The International Renewable Energy Agency estimates that blending green hydrogen in natural gas pipelines costs $500 per ton of CO2 prevented. This compares to the federal government’s estimated $50 per ton cost of atmospheric CO2 and New York’s $150 per ton, making this an economically inefficient way of reducing carbon emissions.

This high cost can directly affect consumers. A German think tank estimated that using hydrogen could increase home heating costs by one-third.[xix]

As with other developing technologies, the cost of hydrogen production is likely to decline steeply in the years to come. For now, though, the price is economically uncompetitive.

In addition, producing hydrogen using wind and solar power would require even more buildout of those sources in order to ensure the clean power to produce it. An alternative zero-emissions energy source would be nuclear power, but at present that also is expensive, and building new nuclear power plants is politically unpopular. 

Backup Energy Production

Given the limitations on energy storage, New York will likely continue to need energy production sources beyond wind and solar. This means reliably dispatchable sources, the most useful of which is natural gas,[xx] as we will see below.

At the maximum, New York will potentially need 100 percent backup for its wind and solar facilities, enough to fully compensate for the needs of the state if a Dunkeflaute is so severe that there is no wind or solar power being produced and storage has been depleted. This will be an additional cost on top of the costs of building out wind and solar and developing energy storage.

In New York, that backup electricity-production system would most likely need to continue to be natural gas. To explain why, it is necessary to show why other sources aren’t ideally suited to being backup power systems and/or are politically unlikely to be acceptable.


Hydropower is a reliable and dispatchable energy source that is also emissions-free. Technologically, it could be an excellent backup system. However, there is little prospect of developing more hydropower within the state. It may be possible to import more hydropower from Quebec in the future, but that requires developing more sources there, which today is fraught with political challenges, both from First Nations groups and environmentalists.

Nuclear Power

As valuable as nuclear power is as a continually operating baseload source, it is not well-suited to ramping up and down quickly in response to demand. To have nuclear power operating to replenish energy storage and meet periods of low wind and solar generation will normally mean having nuclear plants operating at full capacity. That would eliminate the need for any wind and solar production, as nuclear could more reliably provide emissions-free electricity. As discussed above, however, nuclear is a politically unpopular source.


Coal-fired power plants are unlikely to make a return to New York, barring a substantial change in the political environment. But even if the state still used coal power, the long ramp-up period for coal would limit its usefulness as a backup for wind and solar, whose sudden fluctuations require quick response times. While coal can reliably ramp up to meet the predictable daily peak demand, it cannot respond quickly to unpredicted wind lulls or cloud cover.

Natural Gas

This leaves natural gas – whether geologic or renewable - as the most likely backup source of electricity production. Unlike nuclear and coal, natural gas plants can ramp up quickly, in a matter of minutes. A National Bureau of Economic Research paper found that “renewables and fast-reacting fossil technologies [are] highly complementary and . . . should be jointly installed to meet the goals of cutting emissions and ensuring a stable [electricity] supply.”[xxi]

But fast response times require that the natural gas plant be kept on “spinning reserve.” That is, the plant must be burning some fuel at all times to keep its electricity-generating turbines spinning so they can be connected to the grid quickly.

The cost of maintaining a separate backup system capable of generating as much electricity as our wind and solar production combined, is further increased by the cost of continuously burning fuel. And this is regardless of how often the backup is actually brought online.

Because the CLCPA calls for reducing greenhouse gas emissions, geologically-sourced natural gas could potentially be replaced by renewable natural gas, which is carbon-neutral. But like hydrogen, this is a developing technology that is currently very expensive. Therefore this would add even more to the cost of reliable backup.

3. The Necessity of Building More Transmission Lines

Wind and solar often require transmission across greater distances than natural gas or nuclear plants. This is because – setting aside political objections – natural gas and nuclear facilities can be situated in or near urban areas. Distributed solar, mostly rooftop solar photovoltaic, also can be placed in urban areas.

But large wind turbines and large-scale solar farms cannot be placed just anywhere to achieve maximum productivity. The wind and solar farms of Clean Path New York, for example, cannot be located in heavily populated downstate, so they require the building of new long-distance high voltage transmission lines.

Likewise, offshore wind requires development of expensive transmission lines to bring the power to shore.

This is why, even though the direct costs of solar panels and wind turbines have decreased significantly, their overall costs can be higher than building new natural gas plants, and certainly higher than maintaining existing gas plants.


New York can increase its use of intermittent renewables and reduce the amount of greenhouse gas emissions. But it cannot do so cheaply, and it cannot safely do so without a reliable backup energy source. The low price of solar panels and the declining price of onshore wind are misleading. The high price of offshore wind speaks for itself.

These intermittent resources will have to be overbuilt due to their low capacity factors, and will still require reserve sources, which means either buying a vast quantity of batteries at great expense or paying to maintain a full reserve of natural gas and nuclear facilities.

Ultimately, the surest way to secure both CO2 reductions and a reliable electricity supply is to bet heavily on nuclear. That also would not be cheap, but it is the only source that is both emissions-free and highly reliable.

The goal is inexpensive, reliable and non-polluting electricity production. But the practical options are inexpensive and reliable or reliable and non-polluting. Inexpensive and non-polluting is not — for the foreseeable future — an available option.


[i] Thompson, Jonathan P. 2022. ”California’s Grid Briefly Hits 100% Renewables.” Energy News Network. May 3.

[ii] Steppe, John. 2021. ”Iowa Ranks First in Renewable Energy Use, According to New Report.” The Gazette. Aug. 2.

[iii] Makovich, Lawrence, and James Richards. 2017. ”Ensuring Resilient and Efficient Electricity Generation.” IHS Markit.

[iv] Makovich, Lawrence, and James Richards. 2017. ”Ensuring Resilient and Efficient Electricity Generation.” IHS Markit.

[v] Timmons, David, Jonathan M. Harris, and Brian Roach. 2014. The Economics of Renewable Energy. Global Development and Environment Institute, Tufts University.

[vi] Greenstone, Michael, and Ishan Nath. 2019. Do Renewable Portfolio Standards Deliver?”

[vii] Nilsson, Dana. 2020. ”NY-Sun Solar Photovoltaic Program Impact Evaluation for May 1, 2016 through March 31, 2018. New York State Energy Development and Research Agency.

[viii] Cuff, Madeleine. 2021. ” UK Switch to Renewable Power Threatened by Freak Weather, Scientists Warn.” INews. May 24.

[ix] New York Independent System Operator. ”2021 Hourly NYCA Wind.”

[x] New York Independent System Operator. ”2021 Hourly NYCA Wind.”

[xi] Goldman School of Public Policy. 2020. ”2035: The Report.”

[xii] New York State Climate Action Council. 2021. ”Initial Draft Scoping Plan.” p.78.

[xiii] Yeomans, Wes. 2022. ”Winter 2021-2022 Cold Weather Operations.” New York Independent System Operator. April 27.

[xiv] New York Independent System Operator. 2022. ”Power Trends 2022: The Path to a Reliable, Greener Grid for New York.”

[xv] Plautz, Jason. 2022. “New York to Double Energy Storage Target to at Least 6 GW by 2030.” Utility Dive. Jn. 7.

[xvi] Andrews, Roger. 2018. ”The Cost of Wind & Solar Power: Batteries Included. Energy Matters. Nov. 22.

[xvii] Temple, James. 2018. ”The $2.5 Trillion Reason We Can’t Rely on Batteries to Clean Up the Grid.”MIT Technology Review. July 27.

[xviii] Toh, Lucas. 2021. ”Let’s Come Clean: The Renewable Energy Transition Will Be Expensive.” State of the Planet. Columbia Climate School.

[xix] Cembalest, Michael. 2022. ” 2022 Annual Energy Paper: The Elephants in the Room.” J.P. Morgan.

[xx] Romero, Silvia Martinez, and Wendy Hughes. 2015. ”Bringing Variable Renwable Energy Up to Scale: Options for Grid Integration Using Natural Gas and Energy Storage.” World Bank Energy Sector Management Assisstance Program. Technical Report 006/15.

[xxi] Verdolini, Elena, Francesco Vona, and David Popp. 2016. ”Bridging the Gap: Do Fast Reacting Fossil Technologies Facilitate Renewable Energy Diffusion?“ National Bureau of Economic Research. Working Paper 22454.

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