For the majority of environmental funders and others actively involved in fighting climate change, CNN’s recent “Climate Crisis Town Hall” must have seemed like a windfall, as 10 leading Democratic candidates waged what one analyst for the network called “a bidding war to show liberal activists their plan was the most audacious—and even expensive.” But for a small but dedicated corner of climate philanthropy, it was an unmitigated disaster, as one of the surprisings “bids” was a blanket pledge by Senator Elizabeth Warren to rid the United States of nuclear energy by 2035.

According to one such funder, Warren’s vow came as a “gut punch,” as the Massachusetts senator is widely considered a serious student of policy willing to explain and sell complicated tradeoffs to voters. And it followed on the heels of another anti-nuclear blow delivered via cable television,HBO’s runaway hit series Chernobyl, which gruesomely—and, according to some of these experts, inaccurately—portrays the most feared downside of nuclear power.

Despite these setbacks, more than a dozen funders, grantees and others in the nonprofit pro-nuclear space recently interviewed by Inside Philanthropy say they remain committed to their mission, and confident in its ultimate success. Then again, the mission is based on the shared belief that the fate of the Earth is dependent on its success.

Nuclear Awakening

The first thing to know about the field of climate-centered nuclear philanthropy is that, like nuclear energy itself, it is at the same time both very simple and dizzyingly complex.

The simple part is the fundamental reason funders and grantees support nuclear energy: Because they strongly believe that rapidly “decarbonizing” the global economy is impossible or highly unlikely without it.

For one thing, despite the much-publicized rise of renewables, the use of fossil fuels and the resulting emissions continues to rise. And with many millions of people in the developing world still trapped in “energy poverty,” humanity’s thirst for power is only increasing.

While some in the climate community dispute the need for nuclear, often because of the high cost and long delays that in recent years have bedeviled nuclear projects in the West, supporters can increasingly say that the science is “settled” in the technology’s favor. The Intergovernmental Panel on Climate Change—the key international body informing the climate debate—is on record supporting nuclear, as is famed climate scientist James Hansen.

Indeed, to some in the climate movement who see an expanded role for nuclear, the notion that climate change can be stopped or reversed without nuclear is questionable or worse.

“You can run an industrialized grid on solar and wind alone, but there are a lot of ‘ifs’ that have to be satisfied,” says Armond Cohen, executive director and co-founder of the Clean Air Task Force, a research and advocacy group focused on decarbonizing global energy systems, and co-chair of the Nuclear Innovation Alliance, which grew out of the CATF. Among these ifs, says Cohen, are “rapid buildout of hundreds of thousands of plants over big land areas, a massive increase in transmission lines to tie them together, and virtually free energy storage.” But even if all this were done, Cohen says, the financial cost of such a shift will still be substantially higher than if renewables were deployed alongside a power source like nuclear.

According to Cohen, who also serves on the U.S. Department of Energy’s Electricity Advisory Committee, the central issue is that most renewable sources of energy are highly variable. This variation is both from hour to hour and across seasons—by a factor of two to five across months—while electrical grids require 24/7/365 power to match demand across those same periods.

“If you take a Northern Hemisphere grid and push the wind and solar into the system until they hit 60 percent to 70 percent of the total supply of electricity generated, you immediately run into big problems of surpluses and deficits,” he explains.

Beyond the problem of variability (often called “intermittency”) and the open space required to site “grid-scale” wind and solar installations, there is the vast amount of energy and raw materials expended in building them, and the dangers they can pose to wildlife. A single wind turbine can require almost 1,000 tons of steel and more than twice as much concrete, while the short life cycles and composition of solar panels are leading to a major problem of disposal. Meanwhile, wind farms tend to share the same wind-rich migration trails as birds, bats and insects, some of which may face an extinction threat from the turbines’ enormous rotors. And though the U.S. has plenty of land for turbines and panels, many countries are simply too densely populated or removed from regional power grids to decarbonize with renewables only.

“It goes beyond megawatts,” says Rachel Pritzker, president and founder of the Pritzker Innovation Fund, one of the earliest and best-known funders in the space. According to Pritzker and others, not only can nuclear complement renewables in powering the grid, in many cases it is better suited for replacing fossil fuels used by industry, where much of the emissions are associated with the need for onsite heat and power. This is critical, because while most of the focus has been on the electricity sector, industrial emissions account for roughly a fifth of total U.S. emissions, she says.

At the same time, Pritzker says that despite her prominent role in supporting pro-nuclear research and advocacy, she sees it as only one technology among many that will go into decarbonization. “It’s not like nuclear is my thing,” she says. “It is a useful tool to help fix climate, and possibly some of the related politics.”

Other large funders echo the view that nuclear is just a piece of a larger puzzle.

“We fully support the need for more renewable energy, but most research and climate models show that renewables alone are not enough to meet our global climate goals,” says Sam Mar, vice president at Arnold Ventures. “From a philanthropic perspective, organizations supporting a broad portfolio of zero-carbon energy replacements like nuclear are significantly underfunded relative to those with a renewables-only agenda. Particularly in the U.S. in this political environment, supporting nuclear energy innovation is one of the few areas in the climate debate where you can still find bipartisan agreement.”

Mar’s comment that nuclear is underfunded is confirmed by a research paper published last year by Matthew Nisbet, which analyzed $556 million in climate funding from 2011 to 2015 by 19 leading foundations, as well as two regranting organizations. He found that no grants at all “were focused on promoting nuclear energy, though $175,000 in grants were devoted to opposing nuclear energy for cost and safety reasons.”

Talking to Inside Philanthropy after his paper was published, Nisbet said, “You would assume that the foundations would want to hedge their bets, that they’d want to spread their risk around, both from a technology standpoint and from a political strategy standpoint. But it doesn’t seem that they’ve done that.”

Lingering Radioactivity

While the bipartisan political activity that Pritzker and Mar point to is real and significant—Congress in recent years has passed a number of bills aimed at fostering research and development in nuclear technologies—atomic energy remains a powerful taboo for many mainline environmental organizations and their supporters.

As a result, some large climate funders find themselves on both sides of the debate, supporting “big green” groups like the Sierra Club, Friends of the Earth and the National Resources Defense Council, which strongly opposes nuclear power, as well as pro-nuclear organizations and initiatives.

According to Mark Nelson, a senior analyst at the pro-nuclear group Environmental Progress, attempts to bridge the gap between the two sides or even have a dialogue have been frustrating, and in some cases, marred by “bad faith.”

Another problem, Nelson says, is a tendency on the part of some environmental groups or funders to say they are not against nuclear power per se, while at the same time opposing or failing to support any concrete effort to see it deployed in the fight against climate change, such as keeping existing plants open.

“These big organizations will not lift a finger,” Nelson says of the anti-nuclear Big Green groups. “They won’t put their names, money or reputations on the line.”

But according to Mike Berkowitz, a co-founder of Third Plateau Social Impact Strategies, a philanthropic advisory who works with Pritzker and other donors, many nominally anti-nuclear environmental groups are “actively grappling internally with these quite understandable divisions.” He also points out that funders who see a role for nuclear don’t have an easy way to move large environmental groups, since Big Green has historically been more responsive to small donors than large foundations.

Atomized Field

If the basic arguments for and against climate-centered nuclear philanthropy are uncomplicated, the nuclear funding space is much more nebulous.

For one thing, it is hard even to define what constitutes “nuclear philanthropy.” While Matthew Nisbet’s research underscores the lack of targeted foundation support for pro-nuclear programs, Cohen of the Clean Air Task Force and others estimate that as much as $5 to $10 million annually goes into think tanks and advocacy groups like CATF, Environmental Progress and the Nuclear Innovation Alliance. But in recent years, tens of millions in quasi-philanthropic “impact investing” has ended up in technically for-profit companies working to develop new forms of nuclear energy.

Then there is the nexus of government and academia, where the bulk of basic research into nuclear technology has taken place, notably at joint ventures like the Princeton Plasma Physics Laboratory (PPPL), a Department of Energy national laboratory run on a satellite campus of Princeton University. Further adding to the complexity of the public funding environment is the fact that government support for nuclear innovation is spread across different departments and programs.

Meanwhile, unlike with renewables industry, the nuclear industry itself isn’t a reliable funder, in large part because utilities are loathe to see zero-carbon nuclear pitted against other generating sources, notably natural gas-fired plants. “Most nuclear-owning entities are perfectly okay with managed decline,” says Nelson of Environmental Progress. “And an enormous amount of money is made by some parts of the industry when plants are shut down. Firms tearing down reactors get the decommissioning funds saved up over the life of the reactor and the utilities get to walk away from political and financial risk of owning a nuclear plant.” (This situation is less fraught outside of the U.S., where nuclear plants tend to be wholly government-owned and run enterprises.)

Which Nuclear?

Mirroring the ambiguous funding landscape are grantee institutions grappling with—and at times feuding over—a rapidly evolving set of intricate technical, economic and political questions.

After moving past the “no nukes or yes nukes?” question, there is the crucial matter of which types of nukes.

For obvious reasons, donors and impact investors have often favored the development and deployment of advanced technologies burdened with fewer of the risks and drawbacks of the various types of large fission reactors in use around the world today. (Fission, which involves the splitting of atomic nuclei, is the source of all commercial-grade nuclear power produced on Earth today, while fusion combines nuclei as in the sun’s interior, and is not expected to become a meaningful source of energy for at least another decade; advanced or “Generation IV” fission refers to a variety of reactor designs all offering improved efficiency, safety and sustainability, and lower cost.)

While fusion offers the ultimate promise of virtually limitless and safe, waste-free energy, its reputation as a “technology of the future that always remains in the future” has left many nuclear-minded donors cold. One notable exception is the Simons Foundation, which has supported basic research in fusion.

“Advanced fission folks have so far been much better about courting philanthropy than fusion has,” says Andrew Holland, executive director of the Fusion Industry Association, which represents companies working to achieve “breakeven,” the elusive point when the power created by a controlled fusion reaction exceeds the huge amounts of energy required to create and sustain the reaction. “There’s not a lot of support for fusion activism, but there’s a committed core supporting advanced fission activism. And this has helped to create the political conditions that have supported the growth of the advanced fission ecosystem. Relatively small amounts of philanthropic funding can help unlock the massive resources of the U.S. federal government, and governments around the world.”

At the same time, there are many varieties of advanced fission, each with its partisans and detractors. Among the more “mainstream” advanced fission designs are sodium-cooled fast reactors or molten salt reactors (uranium or thorium fueled, including some with liquid fuel that can be replenished without removing the reactor from service), lead-cooled “fast” reactors, and gas-cooled reactors, sometimes known by the ominous-sounding name “very high temperature reactor.” There are also designs similar to the light water reactors currently in use, but with improvements or modifications—such as generating plants built out of a number of small modules—that are significant enough that they’re lumped in as “advanced.”

But as Nelson of Environmental Progress stresses, “Advanced has no systematic definition—it just means ‘not a large light water reactor.’” He also points out pro-nuclear voices in the U.S. tend to overlook reactors like Canada’s tried-and-tested CANDU (Canada Deuterium Uranium) approach, which can run on almost any type of fuel—including waste from other reactors—and is practically immune to major core melt accidents like those at Fukushima and Three Mile Island.

Finally, there are also more exotic reactor concepts, notably the “traveling wave reactor” under development by TerraPower, a for-profit startup whose backers include Bill Gates. (Gates, Jeff Bezos and others have also formed an impact investing/venture capital fund called Breakthrough Energy Ventures to back a range of zero-emissions technologies.)

While there are ongoing and at times heated debates over the pros and cons of each approach, and reactor standardization is seen as a key to bringing costs down, the diversity of approaches is broadly seen as a strength.

Having so many “candidate” solutions not only means healthy technical competition, but a higher profile for advanced as a whole, says Jessica Lovering, who until recently was director of energy at the Breakthrough Institute, a leading “ecomodernist” organization that seeks transformational solutions to the climate crisis (and which is unrelated to Breakthrough Energy Ventures). “Just having actual disagreements [about differing advanced nuclear technologies] keeps nuclear in the conversation,” she says, adding that the differences of opinion aren’t as rancorous as some in the space make them out to be.

Meanwhile, the increasing urgency of the climate crisis has led some pro-nuclear climate hawks to focus their energy on the more rapid deployment of existing technology in new plants, as well as extending the lifespan of the many older “Generation II” reactors slated for closure.

The drive to keep existing reactor “fleets” open has taken on special criticality with government moves to close all reactors in Germany and other countries following the Fukushima Daiichi nuclear disaster in Japan in 2011, and the realization that much of the lost nuclear power would be replaced by fossil fuels, including coal-fired facilities. The situation in the U.S.—where nuclear supplies more than 50 percent of all carbon-free electricity—was starkly illustrated by the closure of the remaining reactor unit at Three Mile Island Nuclear Generating Station in Pennsylvania. The station, which returned to operation after the famous (but ultimately casualty-free) 1979 disaster, was licensed to remain open until 2034, and produced almost 50 percent more power than the largest solar farm in the U.S.. It was shuttered by its owner after a plea for a small price subsidy was rejected, and was turned off the day before the opening of September’s U.N. Climate Action Summit in nearby New York City.

As might be expected, the different challenges and technologies have led pro-nuclear nonprofits to adopt different focus areas and strategies.

“The organizations focused more on advanced fission tend to concentrate on policy research, on driving costs down or market policy that would create demand,” says Lovering, who is a non-resident fellow at the Energy for Growth Hub, a new research and advocacy group focusing on energy and economic development internationally. Meanwhile, she says, organizations focused more on retaining existing plants or building new plants with existing designs center their work on coalition-building and advocacy communications.

Fueling Up

Both funders and grantees say that philanthropy’s potential role in the science and development of nuclear power is significantly constrained, both by the overlap with impact investors and the traditionally dominant role played by government, especially abroad.

Still, advocates and experts point to a number of areas where philanthropy might help, including to bolster fusion.

For his part, Andrew Holland of the Fusion Industry Association sees a role for philanthropy in funding related applied and materials science. He also says donor money would be helpful in funding early research into conceptual reactors not based on tokamaks, the torus-shaped devices most commonly used to magnetically confine incredibly hot fusion reactions. “There are a number of fusion concepts that were cut by the federal program because they didn’t support the tokamak pathway,” Holland says. “They would need in the range of $1 million to $10 million each to get up and running and determine if they have a pathway.”

The key, says Holland, is that the race to save the climate means fusion researchers cannot wait until “the day after breakeven” in the lab to begin work on getting actual fusion plants built and contributing to the grid.

Larry Kramer, president of the Hewlett Foundation, says that a concrete goal for funders should be “helping to finish off the research and development on fourth-generation reactors, then helping develop policies to implement and figuring out where around the world you can build the public support to get them sited.”

And despite the progress being made across the advanced fission space, Cohen of the Clean Air Task Force says that many firms focusing on “truly advanced” technologies are spending too much time raising money, struggling to do $2 million to $3 million rounds. He also believes that donor intervention could be useful in supporting advocacy for R&D and practical nearer-term policy solutions on the longstanding and critical problem of fission waste products.

Meanwhile, Lovering says philanthropy could play a key role in researching the “system effects” involved in pairing nuclear with renewables. “We need more funders interested in the messy overlap” between different energy sources, she says.

Either way, funders who venture into the technical space need to be mindful. “I’d like philanthropy to make sure that the outcomes and results of any research funded are shared and transparent,” says Saul Griffith, CEO of R&D firm OtherLabs, which has worked with the U.S. Department of Energy to map energy flows in the economy and highlight pathways to decarbonization.

Policy First

But Griffith and others stress that even if donor-funded technical research and development doesn’t end up siloed, it’s still better for philanthropy to focus on the political and social hurdles keeping nuclear out of the decarbonization mix.

“I don’t think funders should be placing bets on specific nuclear technologies,” says Sam Thernstrom, CEO of the Energy Innovation Reform Project, a right-leaning Washington, D.C., think tank. “The work should be to advance policies that would move all technologies forward,” adds Thernstrom, stressing that nuclear is just one of a portfolio of carbon-free approaches, each of which will require a different type and level of funder support.

In any case, says Rachel Pritzker, the impact investors who are funding fusion and some advanced nuclear projects tend to be less interested in the policy side of the problem. “People who want to be Tony Stark generally have an aversion to government,” she says, referring to the billionaire superhero-inventor of the Iron Man comic book and movie franchise. “They’re often more inclined to invest directly in technology than fund the advocacy that would help the whole field.”

While significant funding has gone into reforming a regulatory and licensing environment that can add unnecessary years and billions of dollars in costs to nuclear projects, it remains a critical area of ongoing work. And such federal regulation is only one of many policy roadblocks. Pritzker argues that a key funding priority in the U.S. is building coalitions at the state level to ensure that nuclear power is treated by state utility regulators as a zero-carbon energy source. This means that nuclear plants aren’t undercut on price by gas or coal, or by intermittent renewables that will eventually need a complementary source of baseload power.

Internationally, the challenge is somewhat different, and is centered on countering the strong public and political backlash, especially in Europe, against nuclear energy following Fukushima, and what pro-nuclear activists say are especially widespread public misconceptions about nuclear technology. (A recent study in historically very pro-nuclear France found that 86 percent of 18- to 24-year-olds mistakenly believe that the cooling towers of nuclear plants release CO2 rather than water vapor.) And the cooling in Europe has led to a setback in developing countries, as the World Bank in 2013 announced it was suspending all lending to nuclear projects while increasing its support for hydrocarbon-based energy generation as it aims to make access to electricity universal by 2030.

Kramer says that despite the need for a greater international focus in both nuclear and climate as a whole, what happens in the U.S. will remain crucial. “And obviously, we think the outcome of the 2020 election will have profound effects on what happens, and where we go in this space.”

Finally, the international situation is yet another reason some pro-nuclear voices stress that philanthropy should be less wary about being seen as doing the advocacy work of the nuclear industry.

“Why is it our job to do all this advocacy?” asks Jarret Adams, CEO of Washington, D.C.-based Full On Communications, which represents industry groups like the Nuclear Energy Institute. “Here you have the green groups advocating for wind and solar, and the wind and solar companies aren’t paying for them.”

Andrew Holland of the Fusion Energy Association says that philanthropy’s reticence in backing the nuclear industry’s ongoing role in decarbonization stems from a “misreading” of the lessons of how renewables like wind and solar grew and became successful. “The solar energy industry association was founded in 1974, long before it was commercially viable to build out solar power arrays. It was supported by philanthropic donors, who believed that for environmental and energy security reasons, we needed to support a solar industry.”

Either way, the result is a nuclear industry and larger nuclear community that “struggles to communicate the value of their technology,” says Jackie Kempfer of the center-left think tank Third Way. Yet at the same time, Kempfer and others, notably Thernstrom of the center-right Energy Innovation Reform Project, emphasize that the nuclear community does an excellent job in sidestepping the increasingly toxic partisanship that makes doing anything in Washington nearly impossible.

Rachel Pritzker says that this record of bipartisan success was due to the “quiet wonkery” of pro-nuclear groups, and worries that in an era of polarization, noisy public advocacy can be counterproductive.

But others, especially groups focusing on keeping the existing nuclear fleet operating, argue that funders need to do more work addressing nuclear’s public image. “We’ve seen such apathy on the part of funders for advocacy,” says Kristin Zaitz, a project manager at Diablo Canyon, California’s last surviving nuclear plant, who, with a co-worker, founded the NGO Mothers for Nuclear. “They do research and communicate in academic terms,” says Zaitz, referring to existing pro-nuclear groups. “We want to reach people—to change hearts and minds.”

Advocacy and research are not the only non-technical areas pro-nuclear donors are being asked to address. Indeed, one key issue involves refocusing the large volume of funding that foundations have historically directed at nuclear security and nonproliferation. Kempfer of Third Way, who herself has shifted her professional focus from security to climate and energy, says funders should be looking to support work on the “intersections between climate and nonproliferation.” Such a process will likely be of interest to larger institutional funders such as the MacArthur Foundation, which stressed in a statement that its support for nuclear solutions to climate change is contingent on the use of “safe and secure nuclear power that does not increase the risk of nuclear weapons proliferation.”

Either way, according to Kramer, locating the most pressing “hole” that a funder like Hewlett can try to fill isn’t the problem. “We think the whole climate problem is one big hole,” he says. “Everything is underfunded.” At the same time, he says a key constraint for funders is in human and not just financial resources. “It’s a big problem with countless facets. To do philanthropy well, you need people who understand all of them. Just to understand the research, you need more people.”

And going forward, there are likely to be many more issues facing climate funders and grantees who see nuclear as an important weapon in the battle against climate catastrophe. “We need to be able to walk and chew gum at the same time,” says Kempfer. “And we can.”