Key takeaways
- SBTi is the default reference point for corporate climate action: 51% of Fortune Global 500 companies now hold net-zero targets, up from 8% in 2020, and over 11,000 organizations worldwide have SBTi-validated targets.
- Net Zero Standard V2 redefines climate leadership as reducing emissions and mitigating ongoing emissions, not reduction alone.
- The new standard adds flexibility through five-year cycles, a “best efforts” standard, and an Asset Transition Method for companies whose path to net-zero doesn’t fit a straight-line trajectory.
- Voluntary carbon credits are formally recognized for the first time, with reduction and removal credits accepted from 2027, and removals required from 2035.
- Companies with 2030 targets keep using V1 for their current cycle and move to V2 in 2028; companies without targets can start using V2 on February 1, 2027.
Why every business needs to understand the SBTi Net-Zero Standard revision
The Science Based Targets initiative (SBTi) has become the default reference point for credible corporate climate action. Net-zero targets are now held by 51% of Fortune Global 500 (FG500) companies, up dramatically from just 8% in 2020, and more than 11,000 organizations worldwide have set SBTi-validated targets.
However, SBTi’s influence extends well beyond the companies formally participating in the program. Every business in the value chain of an SBTi participant will have to reduce its own carbon emissions, and businesses that aren’t SBTi participants themselves still look to the program for guidance on climate action.
In short, SBTi gives every business a credible blueprint for climate action, and companies that follow its principles can pursue climate action with confidence, whether or not they’re formally part of the program.
How will the Net Zero Standard revision affect business climate action?
SBTi participation is expected to grow. Despite strong target-setting participation among the F500, only 17% of companies use the SBTi Net Zero Standard V1 beyond target setting, largely because its rules have been seen as too rigid to apply in practice. Much of the Net Zero Standard revision has focused on creating more flexibility to enable higher participation. Medium and small businesses will also increasingly feel pressure for climate action, since SBTi mandates that its participants reduce carbon emissions across their value chains.
Net Zero Standard V2 also redefines climate leadership: leading climate action now means reducing emissions and mitigating ongoing emissions. Reducing your own emissions while ignoring the emissions you continue to release along the way is no longer considered leadership. Supporting voluntary carbon projects with high-integrity carbon credits is now backed by the leading authority on corporate climate action.
What lessons shaped the Net Zero Standard V2 revision?
The revision reflects a few learnings about what actually drives climate progress, and how SBTi built those lessons into the new standard.
| Net Zero Standard V1 Learnings | Net Zero Standard V2 Implementation |
|---|---|
| Making real short-term progress is more important and more difficult than making big long-term promises | Focus on short-term climate progress |
| Every company has a different path to net zero that doesn’t always fit generalized net-zero rules | Create asset transition plans based on each company’s unique asset lifecycles and capital planning |
| We need to mitigate our ongoing emissions to keep global carbon emissions in check | Reduce global carbon emissions by financing voluntary carbon projects with high-integrity carbon credits |
What are the key changes between the old and new Net Zero Standard?
Both versions of the standard are grounded in net-zero by 2050. However, the old standard treated climate leadership as simply reducing emissions, expected a long-term commitment to net zero, based emission reduction targets on generalized net-zero goals, revoked status from companies that fell behind on targets, and ignored voluntary carbon projects entirely.
The new standard treats climate leadership as reducing emissions and mitigating ongoing emissions. It shifts the focus to short-term progress through five-year cycles, and it bases emission reduction targets on both the net-zero goal and a company’s own asset decarbonization plan. A new Asset Transition Method lets companies set decarbonization targets through asset plans with committed, verifiable steps; an ambitious but achievable path based on a company’s starting point, financial resources, and technology, with multiple pathways to reflect the unique opportunities and constraints of different industries and companies.
Crucially, the new standard moves to a “best efforts” basis that creates real flexibility on progress against targets. Businesses that miss their targets can keep their status if they’ve used “every lever” within their control, and minimum progress rules will be set out in the SBTi Assurance Manual.
Finally, the new standard formally uses voluntary carbon projects to mitigate ongoing emissions. From 2027 through 2034, this mitigation is recognized, and both carbon reduction and removal credits are accepted. From 2035 forward, mitigation with carbon removal credits becomes required, with durability matching between the removal and the emission it offsets.
| Old Net Zero Standard | New Net Zero Standard |
|---|---|
| Grounded in net-zero by 2050 | Grounded in net-zero by 2050 |
| Climate leadership is reducing emissions | Climate leadership is reducing emissions and mitigating ongoing emissions |
| Make a long-term commitment to net-zero | Focus on short-term progress in 5-year cycles |
| Emission reduction targets are based on net-zero goal |
|
| Businesses who fall behind targets lose status |
|
| Ignores voluntary carbon projects |
|
When does the new Net Zero Standard take effect?
Companies with existing 2030 targets should continue using the old Net Zero Standard for their current cycle, and start using the new Net Zero Standard in 2028 to set targets for the next cycle (2030–2035).
Companies that don’t yet have targets can use the new Net Zero Standard starting February 1, 2027.
What are SBTi’s Category A and Category B companies?
The new Net Zero Standard splits companies into two categories, with different requirements attached to each.
Category A covers large companies from all countries and medium-sized companies from high-income countries. A company from any country qualifies if it meets at least one of: net turnover of €450 million or more, or 1,000 or more full-time employees. A company from a high-income country qualifies if its Scope 1 and 2 emissions are 10,000 tCO2e or more, or if it meets at least two of: balance sheet of €25 million or more, net turnover of €50 million or more, or 250 or more full-time employees.
Category B covers small companies from all countries and medium-sized companies from lower-income countries.
How do Scope 1 targets work under Net Zero Standard V2?
Scope 1 targets aim to transition companies to net-zero direct emissions by 2050 or sooner, and companies can choose from three approaches.
- Absolute emissions reduction follows a straight-line emissions trajectory from the target base year to the net-zero year.
- Emissions intensity reduction lets companies follow sector-specific pathways designed to reflect the reduction opportunities available in sectors like steel, cement, or chemicals.
- Asset transition is designed for companies whose capital stock turnover doesn’t follow a linear or sector pathway. These companies design a transition plan to operate existing assets efficiently and replace them with low-carbon assets, using predetermined milestones.
How do Scope 2 targets work under Net Zero Standard V2?
Scope 2 targets address emissions from purchased electricity through three pathways:
- Reducing electricity consumption,
- Reducing grid consumption by installing onsite or direct-line offsite clean energy generation, and
- Cleaning up the regional grid using market-based tools like PPAs, RECs, and GOs that drive clean energy development.
V2 introduces a dual Scope 2 framework requiring two separate targets, with an overall goal of 100% low-carbon electricity by 2040.
The location-based target addresses the carbon intensity of a company’s physical power use, and requires companies to show that their grid consumption is falling and/or that their physical grid use is getting cleaner; in other words, that their market-based solutions are actually making the grid cleaner.
The market-based (or zero-carbon electricity) target tracks a company’s use of low-carbon power generation contracts and Energy Attribute Certificates. It requires geographical matching of these certificates with electricity consumption based on deliverability regions (grid regions); annual matching is allowed, though hourly matching is encouraged. Category A companies with large electricity loads must report the percentage of their Scope 2 electricity consumption matched with low-carbon attributes on an hourly basis, and there’s an optional recognition framework for companies that meet hourly matching thresholds.
How do Scope 3 targets work under Net Zero Standard V2?
Scope 3 targets share the same 2050-or-sooner net-zero goal, but companies set near-term targets only for material emissions sources in their value chain and areas where they have real influence. Long-term Scope 3 targets are generally not required.
Limited, justified exclusions are allowed for near-term targets, including categories that individually account for less than 5% of total Scope 3 emissions, and activities where a company lacks practical influence, like leased assets it doesn’t operationally control, or the processing of sold products. Optional exclusions are also available in specific categories.
Companies can choose from three approaches to near-term Scope 3 targets:
- An overarching emissions reduction target, which follows a linear contraction of emissions from the base year to residual emissions of 10% or less by 2050 or sooner;
- An overarching supplier/customer alignment target, benchmarked against a growing share of tier 1 suppliers and customers reaching net-zero by 2050 or sooner; or
- A category- or activity-specific target, tailored for companies with concentrated emissions in particular Scope 3 categories or high-emitting activities.
What is “ongoing emissions mitigation” under the new SBTi standard?
This is one of the most significant additions in Net Zero Standard V2. Accelerated climate contributions are needed to help the world achieve climate objectives, limit temperature overshoot, mitigate transition risks, and support the scale-up of climate solutions, and V2 formally recognizes that. Ongoing emissions mitigation runs as a parallel track to companies also reducing their own emissions.
The framework is initially voluntary, with recognition available at three contribution levels to encourage early action.
- Engaged companies address more than 1% of total Scope 1, 2, and 3 emissions.
- Advanced companies address more than 10% of total Scope 1, 2, and 3 emissions, including 100% of Scope 1 and 2 emissions.
- Leadership companies address 100% of total Scope 1, 2, and 3 emissions with a contribution budget of $80/tCO2e.
Carbon credits used for this purpose have to meet certain quality standards. They must be ex-post (issued after the mitigation has actually occurred), independently third-party-assured, emissions reductions or removals, measured in tCO2e, that occur within five years prior to the reporting year. They must be sourced from outside the company’s own value chain. Further minimum criteria will be set to align with high-integrity frameworks, with additional details on the recognition program expected in the second half of 2026.
Starting in 2035, carbon removals become mandatory for Category A companies. From that point, the carbon removal coverage requirement rises linearly from 1% of Scope 1–3 emissions to 100% by a company’s net-zero year. Within that, 10% of long-lived GHG emissions must specifically be covered by durable removals, also rising linearly to 100% by the net-zero year.
How must companies neutralize residual emissions?
At a company’s net-zero target year and thereafter, it must reduce its Scope 1, 2, and 3 emissions to zero or to residual levels, and neutralize all residual emissions using eligible carbon removals. Those removals have to meet two conditions: they must occur within the same reporting period as the residual emissions they’re neutralizing, and long-lived GHGs must be neutralized with long-lived removals, matching the durability of the removal to the atmospheric lifetime of the emission being addressed.
What is the SBTi implementation hierarchy?
Net Zero Standard V2 also lays out how companies should prioritize their actions for credible target delivery, in three tiers.
- Direct actions, at the activity level, are actions that reduce emissions at the source within a company’s own operations and value chain; things like efficiency improvements, fuel switching, and engaging suppliers and customers to reduce their emissions.
- Actions within shared systems, or activity pools that reduce the emissions of shared systems like electricity or gas grids. This includes market instruments that convey low-carbon attributes, such as PPAs, RECs, and GOs, all of which must meet minimum integrity criteria that SBTi will elaborate on in future guidance.
- Sector-level actions relate to the same type of activity occurring in a relevant geography or system, in a way that meaningfully reduces the emissions a company is responsible for.
How Terrapass helps businesses meet the new SBTi standard
As the rules around carbon credits become more rigorous, the quality of the credits behind them matters more than ever. Terrapass has expanded our global network of carbon projects: more project types, locations, prices, ICVCM CCPs, and UN SDGs, spanning super-pollutant destruction, nature-based solutions, and durable removals. We offer Green-e® Climate Certification and we only source from third-party-verified projects on ICVCM-Eligible registries.
We also help clients with impact beyond carbon: EACs, RECs, and GOs including Green-e® Certified credits that support leading renewable energy projects; water credits that support water restoration projects; and custom environmental product needs like RNG and SAF. Wherever your organization is on its sustainability journey, we help clients around the world address climate risk, advance their environmental and social goals, and get the most out of their sustainability budgets.
FAQ: SBTi Net-Zero Standard revision
What is the SBTi Net-Zero Standard?
It’s the framework the Science Based Targets initiative publishes for companies that want validated, credible net-zero targets tied to limiting global warming.
What is changing in the SBTi Net Zero Standard V2 revision?
The biggest changes are more flexibility (five-year cycles and a “best efforts” standard), a new Asset Transition Method for companies whose emissions don’t follow a straight-line path, and formal recognition of voluntary carbon credits for mitigating ongoing emissions.
When do companies need to switch to the new SBTi standard?
If your company already has 2030 targets, you keep using V1 for your current cycle and move to V2 in 2028. If you don’t have targets yet, you can start using V2 as of February 1, 2027.
Can companies use carbon credits to meet SBTi targets?
They can. Under V2, high-integrity carbon reduction and removal credits count toward mitigating ongoing emissions from 2027 through 2034. Starting in 2035, only removal credits count, and they need to be durability-matched to the emissions they offset.
What’s the difference between Category A and Category B companies under SBTi?
Category A is large companies everywhere plus medium-sized companies in high-income countries, based on thresholds like revenue, headcount, or emissions. Category B is small companies everywhere and medium-sized companies in lower-income countries.
What happens if a company misses its SBTi target?
Under the old standard, falling behind could cost a company its SBTi status. Under V2’s “best efforts” approach, a company can hold onto its status as long as it’s used every lever within its control, with minimum progress rules coming in the SBTi Assurance Manual.
Sources: This post is based on Terrapass’s internal analysis of the SBTi Corporate Net-Zero Standard V2.0. Facts and figures were checked against SBTi’s official V2.0 announcement, SBTi’s Corporate Net-Zero Standard V2.0 — Chapter 6: Ongoing Emissions Responsibility, Trellis’s coverage of the standard, Trellis’s reporting on Ongoing Emissions Recognition costs, Sylvera’s analysis of what comes next, Anthesis Group’s Fortune 500 net-zero commitments research, and Climate Impact Partners’ seventh annual FG500 analysis, as reported by CarbonUnits.com.
The post SBTi Net-Zero Standard V2: What the Revision Means for Every Business appeared first on Terrapass.
Carbon Footprint
Why I’m Pro-Nuke Now: Beginning
I composed this essay over much of 2026, as I was writing Beyond Vogtle — my detailed study (co-authored with James Boucher) of U.S. nuclear costs from the 1980s post-Three Mile Island reactors to the Vogtle 3 and 4 units completed earlier in this decade. It traces my journey from nuclear power doubter to proponent.
My story is both general and personal: what was changing in the wide world of nuclear power, energy policy and climate; and how I viewed those changes. I hope this mode of story-telling resonates with a wide audience and also provide a backdrop to “Beyond Vogtle.”
It’s in three parts.
Detail from 1979 rally poster. Full poster appears below.
The first installment begins at the big Washington rally called to mark the Three Mile Island reactor accident, and covers the recession of nuclear dread, the advent of virtually always-on reactor operation, and nuclear’s status as the least carbon-emitting energy supply technology.
Installment #2 begins with the failure (to date) of carbon tax advocacy — “A Climate Cure No One Wanted” — and continues with the closure of Indian Point and the concurrent slow dissolve of my dream that renewable energy could do it all.
The third and final installment begins with a slight detour in which I contrast the appalling human damage from automobility with nuclear power’s increasingly remote dangers, and then return to energy policy with a fresh way to regard nuclear power’s potential contribution to decarbonizing U.S. grids.
Thank for reading. Enjoy. And be sure to look at Beyond Vogtle: What History Tells Us About the Cost of New Nuclear (yes, that’s the full title).
— C.K.
* * * * * * * * *
I’m pro-nuclear power. Big time.
I don’t just want the U.S. to keep running its 95 extant reactors. I want us to build more. Lots more. Hundreds.
I’m not alone. Public opinion is shifting toward nuclear power. But I came to that conclusion after spending years arguing the other side. From the mid-1970s to the late 1980s, I published a raft of critical analyses that got a good deal of public attention ― and even some traction within the nuclear industry itself. My core argument was that the cost of building nuclear plants was rising much faster than the costs of competing sources of energy. The main driver, I said, was a cascade of safety-requirement changes triggered by widespread fears of reactor accidents.
Here’s the full poster.
That work earned me a speaking spot at the massive May 6, 1979 rally in Washington demanding a halt to reactor construction in the wake of the March 28 meltdown at Three Mile Island in Pennsylvania. In the weeks before the rally, my research was cited in hundreds of news stories. At the Capitol, I stood alongside consumer advocate Ralph Nader, the leading figure in the U.S. antinuke movement; actress Jane Fonda, whose new film, “The China Syndrome,” had eerily foretold the Three Mile Island meltdown; and folk-rock icon Jackson Browne. I told the cheering throng that nuclear power was finished.
Cost overruns and canceled reactor projects were putting billions of dollars on the line, and I spent much of the next decade in courtrooms all over the country, explaining patiently to utility regulators why investors, not customers, should bear those losses. I eventually moved on to other public policy work, sparking big-city bicycling and helping bring congestion pricing to New York. But I kept watching nuclear power and the broader energy landscape. Over time, what I saw led me to turn from skeptic to supporter. Here’s why, in eight parts.
1. Fear and Dread Recede
Ask 100 random people today what “TMI” means, and at least 90 will say “Too Much Information.” Maybe one will mention the 1979 accident at Three Mile Island.
That’s a real shift.
The 1970s were commercial nuclear power’s first decade, and the Three Mile Island accident brought it to a terrifying close. Sixty hours into the slow-unfolding crisis, as fears grew that a “hydrogen bubble” in the reactor might explode and rupture the containment dome, CBS Evening News anchor Walter Cronkite captured the nation’s dread: “The world has never known a day quite like today. It faced the considerable uncertainties and dangers of the worst nuclear power plant accident of the atomic age. And the horror tonight is that it could get much worse.”[1]
The stricken reactor was eventually stabilized. But a combination of soaring costs and public apprehension brought an end to nuclear power’s rapid expansion in the United States.
Cronkite’s warning was about Three Mile Island itself, but it seemed to foreshadow more disasters to come. Yet since 1979, the U.S. nuclear industry has accumulated nearly 20 times as much reactor operating experience as it had built up in its entire history before the meltdown, without a sequel.[2] Like the dog that didn’t bark, this quiet fadeout of reactor calamities is an overlooked shift ― and it is prompting a rethink of long-held certitudes about nuclear power.
With each passing year there are fewer people who grew up with dread from Cold War-era A-bomb drills and weapons test fallout that got bundled into nuclear power. There are more young people like Zeke, a Brooklyn high-schooler who in 2019 went to Battery Park City to greet climate activist Greta Thunberg after her sail-powered trans-Atlantic voyage, but who this past May called fears about nuclear power “over-exaggerated.”[3] (Thunberg herself has said that Germany made a mistake by phasing out its nuclear plants, since it led to a sharp rise in coal-fired electricity.)
I’ve heard the same sentiment in hundreds of casual conversations over the past decade ― at climate rallies and on Trader Joe’s checkout lines, in California and in New York. These conversations suggest that the oppositional currents that once compelled federal nuclear regulators to keep piling on costly new safety requirements are losing force.
2. Permanent Peak Performance
Even before construction costs began to soar in the 1970s, nuclear power had another Achilles heel: spotty operating performance.
Throughout the 1970s and 1980s, the U.S. nuclear power sector struggled to maintain even a 60 percent “capacity factor” ― a measure of how much of a plant’s potential output it generates. That’s a dismal rate for equipment that’s expensive to build. I know this because I researched and wrote the first full-length study of shortfalls in U.S. nuclear plant performance, in 1976.[4]
That started to change in the mid-1980s. Plants finished safety upgrades required after Three Mile Island. The industry began sharing best practices ― and mistakes to avoid. Economic incentives helped too, as utility earnings became tied to how often plants actually ran.
A remarkable turnaround, though seldom credited in climate and nuclear discourse.
The turnaround has been dramatic. Since 2000, U.S. nuclear plants have averaged 90 percent capacity factor ― a huge leap from the earlier 60 percent. In effect, downtime has dropped four-fold, from 40 percent of the time to just 10 percent. Repair jobs and retrofits that used to drag on are now precision-scheduled like the train heist in “Breaking Bad.”
The higher reliability brings a huge symbolic benefit. In the 1970s, U.S. reactors seemed to stumble from one fiasco to the next. In Alabama, a technician using a lit candle to locate an air leak started a fire that burned through a thousand cables and knocked two brand-new reactors offline for 19 months. At some ocean-cooled plants, saltwater corroded delicate heat-transfer tubes, forcing protracted repairs. Profits and industry morale took a beating, and nuclear power became a punchline on “The Simpsons.”
Those days are long past. Nuclear power, uniquely, has blossomed into both grid bulwark and climate hero. Thanks to those higher ― much higher! ― capacity factors, each nuclear plant now displaces 50 percent more carbon-emitting power generation than it used to.[5] In fact, at a 90 percent capacity factor, a kilowatt of nuclear power delivers double or triple the climate benefit of a kilowatt of wind power (which averages 30 to 40 percent capacity factor) and roughly five times that of solar (15 to 20 percent) ― a crucial distinction that’s often missing from gushing coverage of renewable energy.
3. Climate to the Fore
Nuclear power’s newfound operational mastery would matter much less but for the urgency of the climate crisis and the persistence of U.S. and global carbon emissions. Like wind and solar, nuclear power generates electricity without burning carbon.
Squint to see that nuclear lifecycle greenhouse gas emissions range from 5.1 to 6.4 (in g CO2 equivalent per kWh); analogous range for solar-PV is 7.4 – 83.0; wind, 7.8 – 23.0. Source, Dinon et al., in report linked in this section’s second paragraph.
It is true that fossil fuels are implicated in nuclear power’s supply chain. Uranium mining uses petroleum, and enriching nuclear fuel requires electricity. But even counting upstream carbon, nuclear power’s climate footprint is smaller than that of wind, solar or hydropower, according to an authoritative 2022 analysis by a multinational team for the UN Economic Commission for Europe. (Their finding matched that of the similarly comprehensive 2018 report by the UN-chartered Intergovernmental Panel on Climate Change.[6])
That’s another big change. In nuclear power’s early years, uranium fuel enrichment was so energy-intensive that the three U.S. “gaseous diffusion” plants were said to consume 10 percent of all electricity used by American factories. But diffusion enrichment has given way to gas centrifuges and, more recently, laser isotopic separation ― methods that use 20 times less energy to isolate fissile U-235 from U-238.
The bottom line: kilowatt-hour for kilowatt-hour, nuclear-generated electricity is at least as effective as solar and wind at cutting climate pollution. Meanwhile, Hurricane Katrina, Superstorm Sandy, “heat domes” and wildfires, and, in August, the first Himalayan glacial collapse, have made once-hypothetical climate death and disruption a daily reality. More than rising electricity demand from A.I., it’s the climate crisis that’s driving renewed interest in nuclear power.
Click here for the second installment, Why I’m Pro-Nuke Now: Beginning.
[1] Quoted passage is from a local (PA) news site, though the an archived Channel 2 broadcast it cited is no longer on line.
[2] The sole “near-miss,” and a major one, was the 2002 discovery by operators at the Davis-Besse nuclear plant near Toledo, OH of extensive corrosion of the reactor vessel head — a vital barrier against loss of coolant and release of radiation. The U.S. General Accounting Office sternly rebuked the Nuclear Regulatory Commission for failing to identify and prevent the corrosion. See GAO, Nuclear Regulation: NRC Needs to More Aggressively and Comprehensively Resolve Issues Related to the Davis-Besse Nuclear Power Plant’s Shutdown, GAO-04-415, May 2004.
[3] In-person conversation at People’s Policy Conference at the New School for Social Research in New York, May 2, 2026.
[4] C. Komanoff, Power Plant Performance: Nuclear and Coal Capacity Factors and Economics (15 MB pdf), Council on Economic Priorities, 1976.
[5] Dividing today’s 90% uptime by the former 60% yields 1.50, indicating 50 percent more kilowatt-hours per kW.
[6] IPCC Annex III report, Technology-Specific Cost and Performance Parameters, 2018. See table on p. 1333.
Carbon Footprint
Why I’m Pro-Nuke Now: Centerpiece
This is the second part of a three-part post. It begins with the failure of carbon tax advocacy and continues with the closure of Indian Point and the concurrent dissolution of my dream that renewable energy could do it all. Part I, “Beginning,” started with the Three Mile Island accident and covered the decline of nuclear dread, the advent of splendidly reliable reactor operation, and nuclear’s climate-hero status. It’s available here. — C.K.
4. A Climate Cure No One Wanted
Nuclear fission, wind turbines, solar panels. Each is a kind of miracle, creating electricity from sunlight, air currents, or the splitting of atoms rather than by setting things on fire. But to economists focused on decarbonization, a greater miracle would have been the widespread adoption of carbon taxes, or, as some prefer to call it, a “price on carbon” — a fee added to fossil fuels’ market price based on their carbon content. Such a tax would shift incentives across the economy away from using fossil fuels, cutting production of the main greenhouse gas, carbon dioxide.
Economists trace the carbon tax idea to the early 20th century British economist Alfred Pigou and his conception of “externalities” ― social costs, like pollution, that aren’t reflected in market prices, and are dumped on communities “external to the process.” My interest dates to the early 1970s, when I was a fledgling environmental analyst in New York City government. I had a front-row seat as an ingenious “sulfur surcharge” eliminated the price advantage of dirty, high-sulfur fuel oil, foiling an eleventh-hour attempt by the oil industry to undercut a groundbreaking clean-air regulation.
Much later, in 2007, I co-founded the Carbon Tax Center, an organization built around the idea of taxing fossil fuels by their carbon content. We proposed a national carbon tax starting at $15 per ton of CO2 and rising in annual steps to $100 within a decade. Our modeling suggested that by then, the myriad changes driven by the financial rewards for burning less carbon would be cutting U.S. emissions by nearly a third ― far more than conventional energy-efficiency standards or clean-energy subsidies.
To be clear, this wasn’t an either-or choice. A carbon tax was unusual in that it reinforced nearly every other decarbonization measure rather than competing with it. But what really set carbon pricing apart was its reach. Carbon taxes would reward every action that reduced fuel use ― not just buying more fuel-efficient cars, but driving less overall; not just laws mandating energy-efficient buildings, but reforming zoning to let new homes be built in town instead of spreading into sprawl; and, in the power sector, switching from higher-carbon coal to lower-carbon gas and from gas to virtually zero-carbon solar, wind, and nuclear power.
A carbon tax would have worked something like New York’s congestion pricing program, which last year began charging drivers $9 a day to enter Manhattan south of 60th Street. Congestion pricing hits gridlock with a one-two punch. The first punch is the price itself: faced with the toll, enough car owners find driving no longer worth it, that traffic actually drops. The second punch is the steady stream of subway improvements funded from the toll revenue — station elevators, real-time train signals, new lines — which pull still more commuters out of cars. Just so, the “stick” of a price and the “carrot” of better alternatives reinforce each other.
I took part in the 20-year campaign that pushed congestion pricing across the finish line. Its advent — and survival — in Trump’s second term is heartening. But it also highlights, by contrast, how little headway has been made toward a U.S. carbon price.
That failure constitutes a tragically missed opportunity for nuclear power, given how much a $100-per-ton carbon price could strengthen its economics. Compared with burning natural gas, the dominant source of U.S. electricity today, a $100/ton CO2 price would give nuclear roughly the same competitive edge as shaving 40 percent off the cost to build new reactors. Or, put another way, that carbon price would be like doubling or tripling what gas-fired power plants pay for pipeline fuel — pushing prices back to pre-fracking scarcity levels.[7])
5. Losing Indian Point
In the spring of 2020, with the COVID-19 pandemic raging, my wife and I fled the city for our cabin in the Adirondacks. One morning I was outside the general store, loading groceries onto my bicycle, when my phone started buzzing. It was Dietmar Detering, someone I knew slightly as leader of the advocacy group Nuclear NY, calling from Queens. I picked up and said hello.
“You call yourself a climate activist,” Dietmar began, his voice sputtering with anger. “Indian Point is being taken apart, and you haven’t said a word to stop it. How dare you?”
I vaguely knew that a 2017 deal ― pushed by the self-proclaimed environmental group Riverkeeper and brokered by then-Gov. Andrew Cuomo ― was about to shut down the Indian Point nuclear plant, located on the Hudson River 35 miles north of midtown Manhattan. The older of its two reactors unit would (literally) get the chop within a week; its twin would follow in a year. Both reactor vessels would be cut to pieces and their radioactive components chemically dissolved. Once that process began, there’d be no turning back.
I stood there holding my phone, stunned. A near-stranger was berating me! I would have hung up, but there was something raw in his voice that I couldn’t ignore. I don’t remember exactly what I said ― probably some version of “don’t blame me.” After all, the carbon tax I’d spent years advocating would have made Indian Point too valuable to shut down. Then I offered what I thought was my strongest point: soon enough, Indian Point’s carbon-free electricity would be replaced by zero-carbon wind and solar anyway, so little harm would be done.
Then Dietmar lowered the boom.
“You don’t get it, do you?,” he said, his voice now cold. “Even if all those new solar panels and wind turbines get built, they won’t displace fossil fuels. They’ll just be replacing carbon-free nuclear electricity that was already protecting the climate. They can’t do both.”
“Wait. What? Say that again.”
“Think of it this way,” Dietmar said. “When new renewables have to replace an existing power source that was already displacing fossil fuels, like Indian Point, their net climate benefit is zero. The renewables you’ve been counting on to push out fossil fuels can’t do that job as long as they’re having to take the place of nuclear plants that were already doing the decarbonizing.”
Full disclosure: those aren’t Dietmar’s exact words. They’re actually mine, drawn from articles I later wrote for Gotham Gazette and The Nation, and from a letter I co-wrote with futurist Stewart Brand, yes, the “Whole Earth Catalog” guy, urging California Gov. Gavin Newsom to halt the planned closure of the Diablo Canyon reactors along his state’s coast. But they capture Dietmar’s central point: shutting down a working nuclear power plant ― or any large source of carbon-free electricity ― nullifies the climate benefit that new replacement wind and solar projects are supposed to provide.
Six years later, Indian Point’s closure still haunts me. Why didn’t I speak up? It’s how I imagine I’d feel if a climbing partner had died because of some mistake I made. In New York, where I live, I measure every increment of renewable energy against the carbon benefit we threw away when Indian Point was shut down and dismantled.
By that gauge, wind and solar look mediocre. Take those 42-inch square “balcony solar” arrays that Germans are buying like hotcakes ― they’re a neat idea, but it would take 50 million of them to match the carbon reduction Indian Point provided, as I wrote here in June. Or consider a rooftop solar setup for the City Island boathouse where my ecologically minded physicist pal stows his sailboat ― fine on its own, but matching Indian Point’s climate value would require solarizing 600,000 similar buildings across the state.[8]
Underneath these daunting numbers is Dietmar’s deeper point: all of this new renewable capacity should have been added on top of Indian Point, not built to replace it.
6. Renewables in a Dimmer Light
Solar and wind power were guiding passions of my adult life. From the 1970s onward, I savored every news story about the latest gains in solar efficiencies and blade lengths. Wind turbines especially stirred me, with their kinetic kinship to bicycles and futuristic look.
Befitting my mathematical bent, I would calculate how much fossil fuel each new wind farm would keep in the ground. For Cape Wind, intended as the first U.S. offshore wind farm, near Cape Cod, I consulted a digest of ballpark dimensions to illustrate how much coal the project would displace each year: enough to cover the entire playing field at Boston’s Fenway Park — foul territory included — in a pile three times the height of the park’s famed “Green Monster” outfield wall.[9]
While I was playing with those numbers, a Stanford mechanical engineering professor named Mark Z. Jacobson was launching a stream of papers spelling out just how many wind turbines and solar panels ― on land, at sea, on rooftops, on farmland or rangeland ― would be required to satisfy the energy needs of different states and countries.
A table in Jacobson’s paper for New York helpfully broke down how much energy had to come from each source. Offshore wind was his largest category, charged with supplying 40 percent of New York State’s energy year-round. The number of turbines: 12,700.
That figure should have given me pause. Filling that quota meant building a hundred Cape Wind projects in the waters off Long Island, even as well-heeled locals including Riverkeeper figurehead Robert F. Kennedy Jr. (yes, that Kennedy) and Walter Cronkite (yes, that Cronkite) were NIMBYing the actual Cape Wind project to death. Ditto, wind projects proposed for the next county over from our cabin in the Adirondacks.
None of those projects were ever built — not just because of local opposition, but also because of a lack of full-throated support from environmentalists who should have championed them for their climate value. Especially in liberal Northeastern states, it seemed impossible to build anything that asked property owners to tolerate construction disruption or changed views, decarbonization be damned.
You might expect the outlook for Jacobson’s all-renewables vision for New York to be improving. Wind turbines are now so prodigious that he can propose 8,000 15-gigawatt turbines instead of 12,700 5-gigawatt ones.[10] And solar power has captured the public’s imagination in a way wind power has not — it’s no accident that climate activist (and Jacobson acolyte) Bill McKibben titled his 2025 call-to-action book, “Here Comes The Sun.”
Nevertheless, the carbon-free electricity lost when Indian Point closed has gone almost entirely unreplaced. Nearly nine-tenths of the power it generated is being made up by burning natural gas — not due to corporate chicanery but because no other source has stepped up. (See chart below.)
And dreams of an all-renewables grid still have to contend with an intrinsic fault ― one even more disabling than the NIMBY opposition sparked by the projects’ thirst for land. That weakness is intermittency: the fact that wind and solar output varies not just day to day, but moment to moment, at the mercy of the weather.
Jacobson has doggedly calculated how many megawatt-hours of wind and solar would be needed to match New York’s ― and other states’ ― total annual energy use. But neither his nor anyone else’s atmospheric models are detailed enough, meteorologically, to verify that a 100% wind-water-solar grid could keep the power on continuously ― hour by hour, year in and year out. Building in extra capacity doesn’t solve this problem. Compensating for weather’s unpredictability by deliberately oversupplying wind and solar, or backing them up with batteries, may look good on paper. But either approach would be punishingly expensive and probably insufficient as well, without ample supplies of reliable, dispatchable power such as nuclear. If there’s no wind, having twice as many turbines won’t help.[11]
In New York, the political fallout from losing Indian Point’s copious ’round-the-clock carbon-free electricity is landing on Cuomo’s successor. With the plant’s closure having pushed New York’s carbon-reduction targets out of reach, Gov. Kathy Hochul this year bowed to reality and froze a 2019 law tying New York’s climate and energy future to renewables. Forces ranging from standard-issue Democrats to grassroots greens are pillorying Hochul as a sellout to Big Oil, though her proposal to add five large reactors across the state — she dubs it her Nuclear Reliability Backbone — is almost certainly a more assured path to decarbonization than the fashionable all-renewables approach.
Click here for the final installment, Why I’m Pro-Nuke Now: Conclusion.
[7] The two representations in the text of carbon pricing’s boost to new reactors’ economics are derived and sourced in my Sept. 2026 paper with James Boucher, Beyond Vogtle: What History Tells Us About the Cost of New Nuclear.
[8] Comparisons in this paragraph employ: 2,028 MW capacity and 90% capacity factor for Indian Point; 220 W capacity and 15% CF for balcony solar. 17 kW capacity and 20% CF for boathouse solar. 10 MW and 40% CF for each wind turbine.
[9] Cape Wind assumptions: 130 3.6-GW turbines and 40% capacity factor yield 1,641 GWh/year. Coal assumptions: 9,800 Btu/kWh, 11,500 Btu/lb of coal, 1.32 coal specific gravity, 62.4 lb of water per cubic foot. Calculations yield 132-foot-high coal pile covering Fenway Park’s 128,000 sq ft surface (est’d from http://www.baseball-statistics.com/Ballparks/Bos/index.htm). That is 3-4x Green Monster height of 37 feet, 2 inches, per Wikipedia.
[10] While Jacobson’s new offshore wind configuration would outproduce its predecessor by nearly two to one, he has also upped his forecast for total required energy, leaving constant offshore wind’s share 40 percent share.
[11] To take a recent example: at the onset of a late June – early July 2026 heat wave, New York State’s wind farms collectively were producing less than one percent of their rated 3,000-megawatt capacity. See my “Beyond Vogtle” report (FN 46) referenced in Footnote 7.
Carbon Footprint
Why I’m Pro-Nuke Now: Conclusion
This concludes my three-part post. Part I, “Beginning,” began with the Three Mile Island accident and covered the decline of nuclear dread, the advent of fabulously reliable reactor operation, and nuclear power’s climate-hero status; it’s available here. Part II, “Centerpiece,” covered the failure of carbon tax advocacy, the closure of Indian Point, and the dissolution of my dream that renewable energy could do it all; it’s available here. This part takes antinuclear activism to task for turning a blind eye to the far more lethal harms from unrestrained automobility, and then turns to the need to redefine “least-cost” decision rules guiding electricity investment. — C.K.
7. A More-Brutal Bête Noire
On a different, but as I’ll show, related topic: I had known for some time that deaths from being struck by a motorist were shockingly common in the U.S., with 300 a year in New York City alone. I had made that fact a central element in defending bicycling against the moral panic over ― of all things ― New York’s industrious bicycle couriers during the pre-digital 1980s. And as a bicycle commuter I had long jousted with drivers. But the death of oncologist Dr. Jie Zhang in 1994 forced me to consider driver-caused traffic violence as an assault on both public health and the moral order.
The horrific death in 1994 of physician and expectant mother Jie Zhang called into question antinuclear dogma that prioritized hypothetical reactor accidents over lethal dangers like unrestrained automobility.
A speeding driver hit and killed Dr. Jie outside Memorial Sloan Kettering Cancer Center on Manhattan’s East Side. She was nine months pregnant. As she lay dying, her colleagues at the hospital delivered her son, who survived. The newspaper ran a photo of the newborn in his father’s arms. My wife and our week-old son were safe at home. My good fortune was hard to bear.
What were the hazards of nuclear power, next to those of motorized traffic? There was and is no agreed-upon damage ratio between the two technologies. But in my eyes, the anti-nukers’ derogatory depictions of U.S. nuclear regulators seemed better suited to officials in charge of “auto safety.” In 2009, for example, after a spate of deaths in SUV rollovers, the National Highway Traffic Safety Administration required that roofs on new vehicles be able to support three times their already swollen weight. That rule led to wider windshield-obstructing structural posts , badly expanding SUV drivers’ blind spots. The result, according to a recent New York Times report, was a tidal wave of crashes that killed hundreds of pedestrians and cyclists and injured thousands more.
As a young attorney in the 1960s, Ralph Nader rocketed to fame by documenting how regulatory capture made cars excessively dangerous. His subsequent pivot to opposing nuclear power initially made sense but, over time, inadvertently left American pedestrians, cyclists, and occupants of smaller vehicles vulnerable not just to “vehicle bloat” but driver distractions and the “windshield perspective” of police, prosecutors and juries.
All the while, anti-nuclear activists keep pounding their drum, willfully ignoring U.S. reactors’ splendid post-seventies safety record (see Sections 1 & 2). With few domestic miscues to flog, they leaned instead into the faraway disasters at Chernobyl (1986) and Fukushima (2011). Those disasters were real enough, but they differed from the U.S. situation not just in location but also in root cause. Soviet and Japanese officials had downplayed reactor risks, while the U.S. nuclear enterprise had built a culture dedicated to containing them.
Even reactor radioactivity, like reactor accidents, is becoming another non-barking dog. We are half-a-century into the age of large-scale deployment of nuclear power, and not a single large-scale study has emerged that credibly pins increased morbidity and/or mortality on nuclear power plant operation. Moreover, the old Rubik’s Cube problem of nuclear waste disposal is yielding to engineered solutions. The hangup was never technical. It was political.
8. By All Means, Decarbonize
For half-a-century, nuclear power and renewable energy have circled each other like wary prizefighters.
The two weren’t simply antithetical, they were incompatible — logistically as well as culturally. One couldn’t be for both; you had to pick a side. That was the gospel of physicist Amory Lovins, whose revolutionary 1976 article in Foreign Affairs magazine, “Energy Strategy: The Road Not Taken,” upended energy policy debates and galvanized the antinuclear power movement.[12]
In Lovins’ influential framing, nukes epitomized “hard” energy — lumbering and brittle. Renewables — wind and solar — were “soft” — home-grown and “right-sized.” (This was before the relentless push for engineering efficiencies turned wind turbines into colossi and blanketed entire fields with solar panels.)
Fifty years on, the climate crisis has entered the ring and demanded that the rivals partner up. The choice now is carbon-burning vs. carbon-free. Further, the perilous timeline of the crisis has toppled another dictum, also traceable to Lovins: that the transition from fossil fuels must proceed under a “least-cost-first” hierarchy that turns to costlier energy sources only after first exhausting all of the less-expensive ones.
Once, that logic was persuasive. In a leisurely, decades-long transition, why not have the lowest-cost energy lead the way? Wherever a home solar array or a Great Plains wind farm could turn a profit, the thousand busy ants of capitalism could be trusted to deploy them. The climate-warping curve would bend, steadily, painlessly, bringing a more flexible and benign energy system into the bargain.
That was the idea. The reality is falling far short, as revealed by the stubborn persistence of U.S. carbon emissions.[13] The manifold causes have been touched on here; they include everything from traditional NIMBYism to viral versions built on conspiracy-mongering, along with supersized pickups, “sport utes” and the absence of robust carbon emissions pricing. The shale revolution and two Trump presidencies did their part as well, keeping fossil fuels cheap (until No. 47 made war on Iran), which added to the stock of carbon in the atmosphere and America’s stock of carbon-consuming cities and towns, farms and roadways.
In World Cup parlance, we’ve entered stoppage time. A new rule applies: nuclear power ― or any other fossil-fuel antidote ― need not pencil out as cheaper than solar or wind to merit a part in decarbonizing U.S. grids. Instead, we should pursue any energy source or energy-saving measure that displaces fossil fuel use at lesser cost than the harm caused by burning those fuels in the first place.
Feb. 11, 1985 cover.
Think of it like the hikers’ joke about the bear: I don’t need to outrun the bear, I just need to outrun you. In the same way, new nuclear plants don’t need to be cheaper per kilowatt-hour than solar or wind. Their electricity just needs to cost less than the added climate damage that would result from burning the fossil fuels that would otherwise fill the gap. And on that test, new nuclear power plants appear likely to succeed.
Let’s break that down.
What will new U.S. reactors cost to build?
This year I applied my statistical skills and power plant knowledge to the 49 most recently built U.S. reactors. Forty-seven of them limped to completion in the dozen years following Three Mile Island. At the time, their swollen costs so ravaged U.S. electric utilities that Forbes magazine termed the U.S. nuclear power program “the largest managerial disaster in business history.”
Nevertheless, my analysis of that cost data points to a path forward. I found that even if future reactor costs track past costs, a program that builds two or more reactors at each site and uses standardized designs will allow new plants to be built for an average cost of $8,200 per kilowatt of capacity, in 2025 dollars. At that price, building and running new reactors is almost certainly a lower-cost proposition than facing the ecological and human damage from burning equivalent fossil fuels.[14]
If anything, my figure is on the pessimistic side, since it bakes in the kind of shifting regulatory requirements that drove up costs so much in the post-TMI period. Even so, it comes to just half of what it cost to build the final two reactors — Georgia Power new Vogtle 3 and 4 units ― a project that nuclear power critics dredge up at every opportunity as proof that any new U.S. nuclear plant is doomed to be uneconomical.
An alternative visualization of this chart appears as Fig. 9 in “Beyond Vogtle.”
Just as important, the odds of future extreme overruns appear low. Using a probabilistic model, I found that the likelihood that a new twin-unit plant, built to a standardized design, will end up costing as much as Vogtle is slim ― the same odds, around 1.7%, as correctly calling six coin flips in a row.[15]
Will the long time to build new reactors undo their climate benefit?
Past nuclear plants seemed to take forever to finish. The 47 reactors whose costs I analyzed averaged nearly 12 years from initiation to completion ― a 50 percent worsening from their 1970s counterparts. Much of that added time traces back to Three Mile Island, which triggered design changes, equipment upgrades, and staffing shifts across the entire U.S. nuclear sector, each adding delays. Slowing demand for power also led some utilities to stretch out construction schedules on their own.
To nuclear power’s critics, these setbacks come with the territory. But reactors aren’t the only major infrastructure projects facing long timelines. Delays in building wind farms, transmission lines, and other accoutrements of renewable energy have prompted plenty of national hand-wringing too. Even balcony solar ― the latest face of decarbonization ― will need time to scale up. Electrical codes and fire regulations must be rewritten, and then the real challenge begins: installing roughly 25 million of these devices (at 220W each) to match the climate benefit of a single 1,000-megawatt reactor.
There’s also a déjà vu tinge to the complaint that nuclear power is too slow to help with the climate crisis. That argument easily predates Vogtle 3 and 4 ― the massive Georgia project that tested residents’ patience and wallets, but is now helping decarbonize Atlanta and hundreds of other cities. The goal isn’t to repeat Vogtle’s egregiously high cost, which doesn’t yet clear the bar set by the social cost of carbon. It’s to treat the climate fight as an ongoing effort to reduce harm by whatever effective means are available.
Balcony solar and giant nukes aren’t rivals ― they’re partners. Building Vogtle didn’t stop Georgians from putting solar panels on their roofs in 2015, and if balcony solar really is the money-saving no-brainer its supporters claim, there’s no reason it shouldn’t help rate-burdened Georgia families in 2027, too. “All hands on deck” is a cliché, but it fits here. The world has no time to wait ― it needs to decarbonize by every means available. Including nuclear power.
[12] Lovins’ Foreign Affairs article is available here. I recounted its momentous impact on energy policy and public discourse for The Electricity Journal in 10 Blows That Stopped Nuclear Power (Jan/Feb 1991).
[13] U.S. CO2 emissions circa averaged only 1 to 2 percent annual reductions over the period 2010-2025, a rate many times slower than needed to meaningfully address the climate crisis.
[14] See Komanoff & Boucher, “Beyond Vogtle,” op. cit., pp. 41-44.
[15] The chance of correctly calling six coin-tosses in a row is one-half raised to the sixth power, which is 1 in 64, or 1.56%, which more or less matches the 1.7% chance that a new nuclear plant will cost as much as or more than Vogtle 3 and 4. See Komanoff & Boucher, op. cit., Fig. 9.
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