Over the past three years, some of the country’s biggest utilities have been committing to a goal that few may have predicted they’d undertake on their own: weaning themselves off carbon-emitting generation by 2050. 

Driving this sea change in long-term planning is a combination of public pressure and energy economics. The falling costs of wind and solar power are pushing utilities to find ways to incorporate them into their long-range plans, even as they struggle to define what resources can be relied on to provide the dispatchable power they need.

At the same time, the increasingly dire effects of global warming are bringing more Americans in line with much of the rest of the world in making carbon-emissions reduction a top policy priority. Utilities in many states now face mandates to move to 100 percent renewable energy or cut carbon to zero by 2050. Others are likely to face similar mandates in short order.

If Joe Biden wins the presidential election in November and Congress enacts his $2 trillion clean energy and infrastructure ambition, utilities will need to reconfigure their plans to meet Biden's nationwide goal of zero-carbon electricity by 2035. At the very least, utilities will need plans that can get them most of the way there, while rushing ahead with next-generation technologies: long-duration energy storage, small modular nuclear reactors or green hydrogen and methane to fuel natural gas peaker plants.

Here's a look at the five largest U.S. utilities by market capitalization that have set net-zero targets so far — how they plan to get there and what stands in their way. 

Dominion Energy 

Virginia-based Dominion Energy is, after NextEra, the largest U.S. utility by market valuation — at least until it completes the sale of its multistate natural-gas business to Berkshire Hathaway Energy. That $9 billion deal is, in turn, part of a broader shift that’s seen the Virginia-based utility first set its own net-zero carbon goals, then have them overtaken by state mandates that will put it under immense pressure to decarbonize its generation fleet. 

Virginia’s Clean Economy Act demands that the state's flagship utility, Dominion Virginia, supply at least 30 percent of its electricity from renewables by 2030 and shut down all carbon-emitting power plants by 2045. That’s a far more aggressive plan than Dominion’s plan to reach net-zero carbon by 2050 across its electric and gas operations serving about 7.5 million customers across 18 states. 

Virginia's new mandate has forced Dominion into a major departure from previous long-term plans to build new natural-gas plants to supply its Virginia electric customers. Its 2020 integrated resource plan (IRP) sets a goal of nearly 16 gigawatts of solar, 5.1 gigawatts of offshore wind and 2.7 gigawatts of energy storage over the next 15 years, nearly quadruple the targets it laid out just last year. While Dominion has planned its offshore wind push for years, the remaining new targets represent a major shift for a resource mix that’s roughly one-third coal, one-third natural gas and one-quarter nuclear, with about 5 percent renewables.

Dominion’s new IRP also eliminates its previous plans to build at least 3,600 megawatts of new natural-gas-fired power plants, although it does call for at least 970 megawatts of gas-fired peaker plants it warns it will need to maintain reliability. Still, that’s a major shift for a utility that announced the sale of its natural-gas business on the same day it and partner Duke canceled the Atlantic Coast Pipeline project, facing multibillion-dollar cost overruns and the likelihood of legal challenges for years to come. 

Duke Energy

North Carolina-based Duke doesn’t face the same state mandates that Dominion now faces — at least not yet. But its self-imposed net-zero carbon by 2050 goals do involve similar tradeoffs between cost and reliability in the short term and uncertainty over viable alternatives in the long term when it comes to managing its natural gas fleet. 

Duke's utilities serve 7.7 million electric customers and 1.6 million natural-gas customers across six states, with a 51,000-megawatt generation portfolio that’s roughly 42 percent natural gas, 33 percent coal, 18 percent nuclear and 7 percent hydro and solar power. Its Duke Energy Renewables arm owns around 2,500 MW of wind power, 1,500 MW of solar and another 4,100 MW of purchased clean energy, mostly solar. 

Duke plans to double its renewables portfolio to 16,000 MW by 2025 through its renewables arm and via large-scale solar deployments by utilities Duke Energy CarolinasDuke Energy Progress and Duke Energy Florida. It’s also promising to retire its more than 10,000 MW of coal-fired power by decade’s end, and reduce its Carolinas-based utilities’ carbon emissions by 50 percent by 2035 — a target that could grow to 70 percent under North Carolina policy in development. 

Duke’s 15-year integrated resource plan for its Carolinas utilities sets out six scenarios that could call for as much as 16.4 GW of solar, 3 GW of onshore wind, and 4.4 GW of storage, as well as an offshore wind scenario with up to 2.9 GW by 2035. The scenarios also envision as much as 9.6 GW of new natural gas, except for a “no new gas” portfolio that would massively expand its need for renewables and storage. 

Longer term, Duke will rely on “zero-emitting load following resources” to replace its gas-fired capacity. That could include replacing natural gas with carbon-neutral hydrogen or methane, or finding cost-effective carbon capture, utilization and storage options. It’s also looking to the potential for small modular nuclear reactors for carbon-free baseload power and long-duration storage technologies such as molten salt, compressed/liquefied air, sub-surface pumped hydro and advanced battery chemistries. 

Southern Company 

Southern Company’s net-zero carbon by 2050 goal is also free of any state mandates for electric utilities Alabama Power, Georgia Power and Mississippi Power, which serve about 4.2 million customers. But the company is no stranger to zero-carbon resource: Its Southern Power competitive power arm owns substantial amounts of wind and solar in its 12.8 GW generation portfolio, while its Southern Nuclear arm generates more than 6 GW of power and is building the country’s only new nuclear plant

Southern’s 44 GW of generating capacity is 52 percent natural gas, 13 percent coal, 17 percent nuclear and 12 percent renewables. The latter category has grown by about 6,500 megawatts since 2012. Southern aims for 14 GW of renewable resources by 2024 between its utilities and Southern Power on its way to cutting carbon emissions by 50 percent by 2030.  

But Southern hasn’t committed to any hard deadlines for closing its coal plants and still plans to build new natural-gas generation in the years to come. Georgia Power’s latest IRP plans to add 2,260 MW of wind, solar and biomass and 80 MW of battery storage, boost its hydropower capacity and shutter five coal plants. But Alabama Power plans to build 2,000 MW of new natural-gas generation, although it’s seeking up to 400 MW of solar and options for additional energy storage under a just-released request for proposals

It’s still unclear how its Southern Company Gas unit, which operates infrastructure across the Eastern U.S., will reduce its emissions to a level to meet its zero-carbon goals. The company’s plan cites options such as cutting operational methane leakage, plus relying on “approaches such as direct air capture of carbon as well as natural methods like afforestation,” which climate activists call insufficient to the task at hand. What’s more, Mississippi Power’s showcase Kemper Plant carbon capture and sequestration pilot project was shut down in 2017 after failing to meet objectives and running billions of dollars over budget. 

Xcel Energy 

Xcel Energy was one of the first utilities to declare a zero-carbon goal without being under the pressure of a state mandate — but that doesn’t mean it’s not likely to face them soon enough. The utility serves about 3.6 million electric and 2 million natural-gas customers in eight states, most of them in Colorado and Minnesota, where public policy is rapidly moving toward a carbon-free future. 

In Colorado, legislation passed in 2019 calls for carbon reduction of 90 percent by 2050, and Gov. Jared Polis is pushing a 100 percent carbon-free plan. Xcel subsidiary Public Service Company of Colorado plans to retire 660 MW of coal-fired power units, about one-third of its remaining coal fleet, and replace it with 1,131 MW of wind, 707 MW of solar and 275 MW of battery storage. That will boost its share of renewable energy to nearly 55 percent by 2026 and reduce coal’s share from 44 percent to 24 percent, although its share of natural gas will remain roughly the same. 

And in Minnesota, where Gov. Tim Walz is asking lawmakers to take up a plan to reach zero-carbon electricity by 2050, Xcel plans to close its last two coal-fired power plants by 2030 and add 1,850 MW of wind power by 2022 and 3,000 MW of solar by 2030. These steps in its Upper Midwest Energy Plan will allow it to hit its 80 percent carbon reduction by 2030 goals for southern Minnesota, western Wisconsin, and small parts of Michigan’s Upper Peninsula and North and South Dakota.

Getting to 100 percent carbon-free electricity by 2050 will be a lot harder, as Xcel CEO Ben Fowke told us last year. Xcel will rely on retaining its nuclear capacity, which is nearly 60 percent of its carbon-free resource mix at present, to reach its target, he said. It will also be seeking out “technologies that are not cost-effective or commercially available today,” from carbon-neutral replacements for natural gas to long-duration energy storage or small-scale nuclear power.  

Public Service Enterprise Group 

New Jersey utility Public Service Enterprise Group is another utility moving just slightly ahead of its home state’s efforts to drive its energy emissions down to zero by midcentury. PSEG’s $3.5 billion clean energy plan is aimed at meeting New Jersey’s renewable portfolio standard of 35 percent by 2025 and 50 percent by 2030, as well as Gov. Phil Murphy’s goal of reaching 100 percent clean energy by 2050. 

Much like Dominion Energy has done, PSEG is divesting from unregulated lines of business to focus on its regulated utilities serving 2.1 million customers in New Jersey and another 1.1 million in New York's Long Island. Last month it unveiled an effort to sell its merchant fossil fuel and solar business, which includes 6,750 MW of fossil generation in New Jersey, Connecticut, New York and Maryland and 467 MW of solar projects across 14 states.

Despite this withdrawal from the competitive solar development business, PSEG’s renewable plans include new solar to add to its 153 MW share of the state’s current solar capacity of more than 2,800 MW. It’s also investing in Ørsted’s 1.1-gigawatt Ocean Wind project, the first of a whopping 7.5 GW by 2035 under the state’s energy plan. It’s also proposing to build 35 MW of energy storage, although New Jersey has yet to make progress on a proposed 600 MW storage build-out by next year. 

Nuclear power plays a large role in PSEG’s carbon-reduction plans. Much like fellow nuclear power plant operator Exelon has done in New York and Illinois, PSEG has enticed state legislators to provide financial backing for its three nuclear power plants in the form of zero-emissions credits (ZECs), moves that have drawn much scrutiny to the reactors’ financial performance.