In 2020, one of two reactors which had been safely operating for decades at the Indian Point nuclear power plant in Buchanan, NY (IP2) was prematurely shuttered. As a result, New York State lost nearly a fifth of its total nuclear capacity and 10% of all carbon-free generation statewide—more electricity than is produced annually by every solar panel and wind turbine in the state. Worse, those figures will double if Indian Point’s remaining reactor (IP3) shuts down in 2021. Most severely impacted will be downstate residents, who already suffer from air pollution and will be tied to a regional electric grid powered almost exclusively by fossil fuels starting in April.

Despite this major setback to New York’s climate and justice goals, many well-intentioned activists are celebrating in the belief that electricity from Indian Point is being rapidly replaced by renewables and energy efficiency. Contributing to this misconception is a brief posted by Physicians, Scientists, and Engineers (PSE) last year. Titled Evaluating the potential for renewables, storage, and energy efficiency to offset retiring nuclear power generation in New York, PSE’s brief has been referenced in opinion pieces and anti-nuclear mailings as evidence that the state does not need nuclear power and is well on its way to a 100% renewable grid. This is not so.

“We respect other work by PSE to bring attention to the significant climate and health impacts of continued fossil fuel consumption. However, we are compelled to respond to aspects of its brief on Indian Point that paint a misleading picture of energy in New York,” said Isuru Seneviratne. Joined by Dr. James Hansen of Columbia’s Earth Institute, Seneviratne and others have prepared a critique of PSE’s seven-page document and its conclusions. Their critique discusses errors and oversights of the brief, recognizing the challenges associated with designing systems capable of meeting energy needs in the real world. Such an understanding is particularly important as New York seeks to implement the state’s Climate Leadership and Community Protection Act (CLCPA), which calls for a rapid transition to carbon-free electricity and as the nation renews its commitment to tackling climate change.

Read the full critique


Understanding the Impact

In 2019, nuclear power comprised a third of total electricity generation in New York and was responsible for over half of carbon-free electricity statewide. Located in the lower Hudson Valley, the two nuclear reactors at Indian Point produced a quarter of the downstate region’s electricity and nearly all of its carbon-free electricity.

2019 Generation Mix
New York statewide solar and wind generation compared with carbon-free output from Indian Point units 2 and 3

Wind and solar (utility-scale and “behind the meter”) in New York were responsible for about 6,600 gigawatt-hours (GWh) of electricity in 2019. However, Indian Point generated 16,695 GWh. This means that from a climate standpoint, shutting down just half of Indian Point wiped out more carbon-free electricity than is annually produced by every wind turbine and solar panel in the state.

Moreover, with a capacity factor of 91%, Indian Point generates reliable baseload electricity. This means that shutting down IP2 created a very large, immediate, and continuous gap in real energy generation which had to be filled. Following closure of IP2, that gap has been filled with fossil fuels, primarily methane—also known as “natural” gas.

This is readily apparent by comparing generation data for the eight months of May through December in 2020 following deactivation of IP2 to the same period in 2019. Despite 2,753 GWh of reduced energy demand during the COVID pandemic, New York generated significantly more electricity, 5,068 GWh, from fossil fuels in 2020 than in 2019 because of lost nuclear power.

Due to greater fossil fuel consumption, shutting down IP2 results in the annual production of about 4 million tons of avoidable carbon dioxide emissions (twice this in CO2-equivalent greenhouse gases if lifecycle methane emissions are included). This impact will double if IP3 closes in 2021. However, losing downstate nuclear power not only moves New York backwards on climate change; it subtracts emission-free energy from the grid in a part of the state where—except for Indian Point itself—electricity is generated almost entirely from fossil fuels. Shuttering Indian Point exacerbates poor air quality as more fossil fuels are burned in giant new gas-fired power plants within the lower Hudson Valley—680 MW CPV Valley Energy Center (CPV) and 1,020 MW Cricket Valley Energy Center (CVE). It also harms Environmental Justice communities which suffer from old, polluting oil and gas plants that will remain in operation longer, and that may need to run more, within the densely-populated New York City metropolitan area.

NY Generation Mix Before and After IP2

PSE’s Flawed Analysis: “Replacing” Indian Point

Although claiming to analyze the “replacement” of electricity from Indian Point, PSE’s brief goes no further than its title suggests, which is to evaluate the potential for “offsetting” watts or watt-hours from Indian Point with electricity from other sources. The brief does not fully consider the function that Indian Point performs within the downstate electric grid. Instead, it redefines the task of replacement, saying that success is achieved if additional recent or projected gains in local renewable energy and energy efficiency equal the nameplate capacity of Indian Point at peak times; and if additional recent or projected gains in renewables and efficiency exist statewide to equal the total annual generation of Indian Point. This approach is flawed for several reasons: It inappropriately counts existing renewable and energy efficiency gains that were displacing fossil fuels; it does not adequately consider the real-time impacts of intermittency; and it dismisses physical constraints of transmission and deployment at scale.

Reallocation of Existing Renewables and Efficiency

In its brief, PSE inappropriately credits renewable energy and efficiency measures deployed three years prior to the closure of IP2 toward replacement of Indian Point. Whether installed recently or years ago, existing renewables provide electricity to the grid when they can and reduce the need for generation from fossil fuel power plants. If those existing renewables are subsequently reallocated to the displacement of nuclear power, they can no longer displace fossil fuels and more fossil fuels will be burned—precisely what occurred in New York last year. Likewise, existing gains in energy efficiency have already been absorbed into the broader energy system, reducing demand and avoiding generation from fossil fuel power plants. If those efficiency gains are later credited with the replacement of nuclear power, previously avoided generation from fossil fuels will occur. The brief makes this mistake in its analysis of both local capacity and statewide generation. PSE’s discussion of “compensatory megawatts”, identified in an Indian Point deactivation assessment by the New York Independent System Operation (NYISO), is also misleading. In that assessment, NYISO found that electricity from three new gas plants (CPV, CVE, and Bayonne Uprate) would not be needed for reliability until 2023 only because excess capacity is available from previously existing power plants in the region. Utilizing “excess capacity” means burning more fossil fuels.

PSE vaguely acknowledges that fossil-fuel power plants may need to run more due to Indian Point’s closure. However, it excuses this, saying “…a portion of the plant’s generation might temporarily be replaced with gas generation rather than renewables. A short-term demand for gas generation could likely be met by existing plants, however, without the need to build new gas infrastructure.” This latter point is rendered moot by the fact that giant new gas power plants explicitly built to replace Indian Point are already operating. Moreover, the brief fails to define “temporary” or quantify the impacts of additional gas-fired generation on carbon emissions or air quality within affected communities. From the standpoint of Environmental Justice, of particular concern is the ramping up of older facilities within the NYC metropolitan area.

Gains in renewables and efficiency prior to the closure of IP2 were not held in a lockbox waiting to replace nuclear power. They had been put to good use, reducing fossil fuels consumption, particularly gas. When IP2 closed, those good uses were forfeited, causing more gas to be burned.


PSE’s brief acknowledges the intermittency of renewables, but does not seriously consider the real-world challenges created by it. This results in an apples-to-oranges comparison of dissimilar energy sources. In analyzing local capacity, PSE multiplies the nameplate capacity of existing and projected solar projects by winter and summer capacity factors to calculate what it describes as winter and summer peaking capacities, which it then applies to Indian Point replacement. However, this is not the same as available power. The amount of power that an intermittent source can produce ranges anywhere from zero up to its rated nameplate capacity, depending on particular conditions at any given time. In its assessment, PSE also recites various CLCPA targets for the deployment of solar and offshore wind. But the capacities of intermittent sources are not necessarily additive, nor can they be considered “replacement” for baseload generation. Similar extraneous calculations are performed for efficiency. The very nature of intermittency means that electricity may not be available when it is needed, including during peak periods.

These problems are also seen in PSE’s discussion of annual generation. To claim that one source of electricity “replaces” another, the alternative must reliably provide the same amount of electricity at the same times (and to the same places) as the source being eliminated, thus satisfying the same real-time load demands. For this reason, the total amount of electricity generated annually by wind and solar across New York is of little relevance in determining whether nuclear power can be removed from the downstate grid without burning more fossil fuels. The brief asserts that statewide renewable resources can replace Indian Point’s non-peak generation, but this is not necessarily so. Whether intermittent sources are local or statewide, their ability to replace nuclear power depends on when they are generating electricity, and how much they are generating at any given time, in addition to transmission constraints. Treating all watt-hours equally—regardless of when or where they are generated and when or where they are needed—ignores the dynamics of grid operation. Nevertheless, this is what PSE does by summing annual watt-hours of renewable energy and efficiency as “replacement” for Indian Point.

Consequences of Intermittency

As more wind and solar are deployed, intermittency becomes increasingly difficult and costly to overcome. Storage can help, but understanding its practical limitations is important. The largest battery in the world is California’s 1200 Megawatt-hour (MWh) Moss Landing project. This corresponds to only about a half-hour of the energy that Indian Point delivered reliably 24 hours a day prior to the loss of IP2. Notably, Ravenswood Development has proposed a 316 MW battery with eight hours of storage in Queens, NY. However, this constitutes merely 15% of Indian Point’s deliverable power, and if configured to match its power output, only about 80 minutes’ worth of Indian Point’s energy. These facilities do not come close to replacing the important function served by Indian Point in delivering reliable, baseload electricity. Any real-world system must account for a wide range of operating conditions, which makes determining the amount of storage needed to achieve reliability for different levels of renewable penetration a complex statistical analysis. Although the title of PSE’s brief claims to evaluate the potential for storage to make up for the loss of Indian Point, the brief does not do this. It merely says that “hourly grid modeling will be necessary.” Rather than analyzing storage needs and limitations, the brief restates battery capacity goals of the CLCPA in watts, which is a measure of deliverable power, not storable energy.

Advances in technology have allowed batteries, sometimes coupled with renewables, to become a viable alternative to “peaker” plants that run only for limited amounts of time during periods of peak load. However, this has little impact on baseload demand. Where large amounts of intermittent sources are deployed, as in California, dispatchable gas combustion is needed to serve customers when wind and sunshine are not available. This “partnering” creates a dependency on gas that thwarts the goal of carbon-free electricity. It also leads to inefficient gas-fired generation—typically resulting in frequent startup and shutdown which degrades performance, the use of simple-cycle plants that respond quickly but consume more gas per watt-hour, or running plants in “hot standby” (meaning that fuel is burned even when not making electricity). Operating a network this way may help to prop up arbitrary renewable energy targets, but it undermines the fundamental goal of greenhouse gas reduction. Another consequence of adding significant wind and solar to the grid is the production of electricity when it is not needed. If excess energy cannot be used or stored, it must be curtailed (“dumped”), resulting in even lower effective capacity factors, systemwide inefficiency, and increased cost of building and maintaining underutilized resources.

The difficulties of matching supply with demand grow exponentially as intermittent sources comprise larger and larger portions of total generation. However, PSE neglects this, suggesting that current efforts are also applicable to the retirement of other nuclear plants in New York. Retaining “firm” carbon-free capacity, which nuclear power provides, is essential to any real-world plan to ensure reliability while meeting climate goals.

Transmission Constraints and Energy Density

Contrary to common belief, there would be very little “local” about a grid dominated by intermittent renewables. Robust and flexible paths must exist for electricity to flow, potentially very long distances, from wherever electricity happens to be generated to wherever it is needed. Power lines and transformers cannot move in response to dynamically changing pathways, so this requires the large-scale expansion of transmission infrastructure. This is not fully appreciated in PSE’s brief. The brief highlights new transmission capacity coming online in 2023 as if such improvements can be devoted to Indian Point’s replacement without regard to other needs for congestion relief (which had been an issue prior to IP2’s closure), or to further transmission improvements required to replace downstate fossil fuels. The brief also improperly sums the capacity of transmission projects connected in series. Constraints that impact electricity transmission within local distribution networks elsewhere cannot be ignored either. For example, the brief predicts significant amounts of new renewable generation statewide between 2020 and 2025. However, it is not valid to credit electricity produced from rooftop solar panels in Buffalo (which in all likelihood does not leave Buffalo), along with every other incremental production of renewable electricity throughout New York, against electricity produced by Indian Point to serve the downstate metropolitan area. The same applies to efficiency. Installing LED lighting upstate does not reduce the demand for electricity in New York City or the need for transmission capacity to delivery that electricity from sources outside the region.

The very low energy density of intermittent renewables will also make achieving New York’s energy goals extremely difficult, a reality understated by PSE. Even with offshore wind, unless New York imports much of the electricity it consumes, tremendous amounts of wind and solar will still have to be deployed throughout the state in an extremely short amount of time. This in turn will require the very rapid siting, permitting, and construction of intermittent resources over large areas, along with associated transmission and storage infrastructure—all of which have environmental impacts that must be considered. Even in politically progressive states and western Europe where renewable energy is generally supported, the tolerance level for such expansion diminishes as renewables and related infrastructure consume an increasingly large amount of the landscape, and as the cost of implementation puts an ever-growing burden on ratepayers. Prudent consideration of these factors would dictate preserving energy dense, carbon-free assets that already exist, rather than eliminating them.

The Bigger Picture

By comparing existing and projected gains in renewable energy and efficiency with the singular objective of replacing Indian Point, PSE overlooks perhaps the most compelling reason for not closing Indian Point—which is how far New York still must go to meet its energy and climate goals.

Achieving greenhouse gas reduction goals will require the widespread beneficial electrification of sectors that presently rely on combustion, including transportation, heating, and industry. This in turn will increase electricity demand. Even with aggressive improvements in energy efficiency, a recent climate change impact study prepared for NYISO estimated that New York will require 221 terawatt-hours (TWh) of electricity in 2040, a 40% increase over levels originally forecast for 2020. Moreover, all of this must be carbon-free to comply with the CLCPA. The same study estimates that New York will require 258 TWh of electricity in 2050, a 63% increase over 2020. While PSE’s brief lauds the state’s plan to install 9,000 MW of off-shore wind by 2035, those wind turbines would generate only a sixth of the carbon-free electricity needed just five years later—deliverable statewide, summer and winter, day and night, rain or shine.

Plotting watt-hours of generation today, renewable and efficiency gains anticipated by PSE through 2025, and total carbon-free electricity and efficiency improvements needed in the future to reach state goals, the facts are clear: Losing Indian Point will set the state back by years. Further, projected growth in wind and solar, claimed by PSE to replace Indian Point, is anemic relative to what is necessary to achieve state climate goals.

NY CLCPA Electricity Needs

In 2010, Germany undertook ‘Energiewende,’ a nationwide campaign to address climate change and transition to renewable energy. However, in parallel, the country decided to eliminate its fleet of nuclear power plants, wiping out carbon-free electricity that once provided over a quarter of its total electricity. Despite half a trillion Euros invested in wind and solar, Germany has become increasingly dependent on foreign gas, still relies heavily on coal, and in 2020 even fired-up a new coal plant. To compensate for intermittent sources, the country depends on electricity produced by burning fossil fuels at home and in neighboring countries. Under the pretense of “renewable energy”, it also burns wood from forests that had previously sequestered carbon and crops from farmland that could have fed people. It is ironic that despite its own aversion to nuclear power, Germany continues to import electricity from nuclear power plants in France. Meanwhile, France—which receives almost all of its electricity from nuclear—has among the lowest carbon emissions and cleanest air in Europe. Similarly, in the U.S., California has managed to increase non-hydro renewables to about a third of electricity generation. However, since it is eliminating nuclear power, the state continues to burn about as much gas for electricity as it has for the past two decades, while customers suffer from soaring electric rates and rolling blackouts that reveal the fragility of an impaired grid.

New York should learn from failed experiments elsewhere rather than trying to repeat them while hoping for a different outcome. In the absence of carbon-free nuclear power, fossil fuels will almost certainly remain an inextricable part of New York’s grid. If the state is to meet its aggressive energy and climate goals, it cannot afford to lose any carbon-free source of energy, especially one that produces reliable baseload electricity.

Misguided Priorities

Perhaps of greatest consequence, the PSE brief fails to address a fundamental question: Even if it were possible to replace Indian Point with renewable energy and efficiency, how is that an appropriate decision when the widespread consensus of scientists is that climate change is the greatest existential crisis of our time—and that time to respond is running out? Why should New Yorkers squander gains in renewables and efficiency to eliminate a carbon-free source of electricity, instead of applying those investments to the reduction of fossil fuels?

Regardless of whether some, or even all, of the electricity from Indian Point might be “replaced” by renewable energy and efficiency, closing Indian Point will result in the continued reliance on fossil fuel power plants that could have been shut down instead. From both a climate and public health standpoint, closing any of the large fossil fuel plants in New York City, or avoiding construction of CPV or CVE, would have been a more responsible decision. This could have avoided over 16,700 GWh of generation from fossil fuels annually, prevented millions of tons of greenhouse gases from entering the atmosphere every year, and reduced air pollution that threatens public health. By admitting that the closure of Indian Point may result in more gas use “temporarily”, PSE seems to imply that we have time to spare on climate change. In suggesting that Indian Point’s closure could have been accomplished by relying more on “existing” gas plants, PSE neglects the impact that doing so has on affected communities.


The climate crisis is upon us. Anything less than an accurate, disciplined analysis of our current circumstances and prospects for addressing them is a disservice to future generations. Moreover, responsible technical advocacy would dictate lending support to strategies with the greatest potential for success rather than those that put an exceptionally difficult task further out of reach. Large gas-fired power plants are now in operation and older fossil-fuel plants within vulnerable communities of New York City will need to run more, or run longer, due to the closure of Indian Point. Although perhaps not PSE’s intention, the consequence of its brief has been to bolster the unrealistic notion that New York can achieve its greenhouse gas reduction goals and satisfy the state’s growing demand for electricity with just renewable energy in 19 years. The fact is that in the CLCPA’s first year, the state has already lurched backwards. Making up lost ground and delivering on New York’s climate goals will require that state planners, and others engaged in energy policy, recognize the important role nuclear power must continue to play in the future.