Technologies that remove carbon-dioxide from the atmosphere are helpful if we want to get to net-zero emissions, and critical if we want to drive down CO2 levels to where they were before the Industrial Revolution.

There are several approaches to carbon removal, such as planting more trees, sequestering carbon in soils and directly capturing CO2 from the atmosphere with machines. This last option, known as direct air capture (or DAC), is particularly powerful because the technology is modular, which means we can make many copies of the same design, and it can be deployed anywhere.

Unlike other pollutants, what matters with carbon dioxide isn’t the location of its release but the total atmospheric accumulation. Releasing greenhouse gases in industrial corridors and then removing them from the atmosphere in remote locations has essentially the same net effect as if the carbon wasn’t emitted in the first place. That means we can deploy DAC systems wherever the energy for their operation is cheapest, ecosystem impacts are lowest, and the economic activity would be welcome.

The modularity of DAC systems implies that costs for CO2 removal might drop 90% to 95% over a couple of decades, just like the recent cost declines for other modular solutions such as wind turbines, solar panels and lithium-ion batteries.

This isn’t a fantasy: In September 2021, Iceland started deploying geothermal energy to power a DAC system that removes CO2 and permanently sequesters it below ground. Now that we know it works, it is a matter of scaling up. There are many innovative companies in this space, so that means figuring out collectively how to lower the cost and energy requirements for carbon removal—whether it be from clever engineering, novel scrubbing materials or whole new approaches—and then deploying as many of that design as possible.

Solar Microgrids

is an adjunct professor in the department of electrical engineering and computer science at the University of California, Berkeley. She also directs the Electric Grid Research program at the California Institute for Energy and Environment and the Center for Information Technology Research in the Interest of Society (Citris).

Climate technologies are more likely to go viral if they also address pain points energy consumers face today. Solar microgrids, helped by information technology, have the potential to be such a solution, able to accomplish climate mitigation and adaptation at the same time.

What do people really want when it comes to energy? Security. That means health and safety, comfort, and knowing that your essential needs will be covered even during a crisis, such as a power outage associated with an extreme weather event or wildfire.

A solar microgrid, which generates, stores and distributes clean energy to homes and facilities in a local network, provides a strong answer to these needs and wants. It can integrate with the main electric grid or disconnect and operate autonomously if the main grid is stressed or goes down. The physical pieces—solar panels, batteries and inverters—have been improving for a while. What’s new and coming, though, is the ability to orchestrate these different pieces into agile electric grids.

With digital tools and data science, demand for energy can now be sculpted locally to match available resources, reducing the number of power plants that utilities need to keep in reserve. The key is giving consumers the ability to separate flexible energy uses—say, operating a Jacuzzi—from essential needs, which can now be done with phone apps for smart appliances and service panels.

Meanwhile, connections between groups of customers can be opened and closed as needed with modern, communicating circuit switchgear. On most days, solar microgrids will stay connected to the main grid, importing or exporting power as needed to help balance the load. During emergencies, though, they can operate safely as power islands of different sizes to sustain vital services.

Such adaptability will unlock the priceless benefits of local security, while continuing to allow access to inexpensive bulk energy through the macro-grid. In this way, solar microgrids can become a flexible and affordable solution to our climate challenges.

Enhanced Energy Storage

is a research professor and managing director of the Climate Policy Lab at the Fletcher School at Tufts University.

Batteries are a critical technology for expanding renewable-energy use, collecting solar and wind power at times of low demand so it can be redeployed later when more electricity is needed.

The good news is that record amounts of batteries are being installed in U.S. homes and on the electric grid, despite supply-chain bottlenecks. The bad news is that current battery technology only offers a few hours of storage. What’s needed are more-powerful battery systems that can extend the length or scale of storing, which could be even more enabling to sun and wind power.

Two such solutions are on the horizon. Stationary metal-air batteries, such as iron-air batteries, don’t hold as much energy per kilogram as lithium-ion batteries so it takes a larger, heavier battery to do the job. But they are cheaper, iron is a plentiful metal, and the batteries, whose chemistry works via interaction of the metal with air, can be sized and installed to store and discharge a large level of electricity over days or weeks. While not an option for cars due to heavy weight and size, improved large iron-air batteries are poised to become a great new backup for renewable energy within the next couple of years to address those times of year when drops in renewable energy production can last for days and not hours.

For households, a battery configuration called a virtual power plant also holds huge potential to extend the use of renewables. These systems allow a local utility or electricity distributor to collect excess energy stored in multiple households’ battery systems and feed it back to the grid when there is a surge in demand or generation shortfall.

Greener Shipping

is the director and Taylor Goelz the program manager of the Aspen Institute Shipping Decarbonization Initiative.

Maritime shipping is considered challenging to decarbonize because of the industry’s global, distributed nature and a lack of ready clean-energy alternatives. But thanks to promising emerging technologies, as well as growing public pressure and regulatory interest, investment in zero-emissions shipping is starting to heat up.

Electrification is a good choice for smaller vessels on short voyages, like the world’s largest all-electric ferry launched in Norway in 2021. It isn’t yet a viable option for ships on transoceanic voyages because batteries are still too large and heavy, though innovative approaches for battery swapping are being explored.

For longer voyages, e-ammonia, a hydrogen-derived fuel made with renewable energy, has been identified as a prime candidate, although work is needed to ensure safety. Ammonia has a higher energy density than some other options, making it a more economical option for powering large ships across oceans. It also has potential for lower life-cycle emissions if renewable energy is used as an energy source. Among ammonia projects in the works, MAN Energy Solutions is developing engines that can run on conventional fossil fuel or ammonia, a coalition of Nordic partners is designing the world’s first ammonia-powered vessel, and Singapore is evaluating how to bunker the fuel.

Others in the industry are investing in green fuels that may be ready for deployment sooner, such as e-methanol, which can be made by combining renewable-energy-generated hydrogen with carbon from direct air capture or biogenic sources. Most studies, however, predict e-ammonia outcompeting e-methanol on cost in the long term.

Policy support, cross-sector collaboration and private investment will be needed to deploy and rapidly scale these solutions, but the payoff could be significant. Maritime shipping currently emits approximately 1 billion tons of greenhouse gases a year, equivalent to the emissions from all U.S. coal-fired power plants combined. Without intervention, shipping’s emissions footprint could triple by 2050, threatening achievement of Paris Agreement goals.

Innovation in EV Batteries

is a professor of management and director of the Program on Vehicle and Mobility Innovation at the Mack Institute for Innovation Management at the University of Pennsylvania’s Wharton School.

Shortages of battery materials are widely seen as a brake on electric vehicles’ growth. But alternative battery chemistries that minimize or avoid the most problematic raw materials could circumvent these constraints within the next few years.

Most EV makers chose a nickel-manganese-cobalt combination for their lithium-ion batteries because it delivers the most power density, and hence longer range, for the buck. But it also relies on two problematic minerals—nickel, for which supplies are limited, and cobalt, which is both scarce and plagued by unsafe mining and exploitation of child labor. NMC batteries also can burst into flames under certain conditions.

Some EV makers such as Tesla are now embracing an older, less-expensive battery technology known as lithium-iron-phosphate, or LFP, used originally in scooters and small EVs in China. It draws entirely on cheap and abundant minerals and is less flammable. The power density of LFP is less than NMC, but that disadvantage can be overcome by advances in vehicle design.

One approach being tested eliminates the outer packaging of the batteries altogether and directly installs cells, packed in layers, into a cavity in the EV’s body chassis. This design saves weight and boosts power density and, coupled with software tweaks, could help alternative battery chemistries like LFP deliver a longer-range charge.

Eventually, solid-state batteries—with a solid electrolyte made from common minerals like glass or ceramics—could become a key EV battery technology. (So far, they can be found only in pacemakers and smartwatches.) The solid electrolyte is more chemically stable, lighter, recharges faster and has many more lifetime recharging cycles than lithium-ion batteries, which depend on heavy liquid electrolytes.

Overall, these innovations are good news for those hoping to speed up EV adoption. They also suggest that batteries, far from becoming a standardized commodity, are going to be customized as auto makers create their own vehicle designs and battery makers develop proprietary platforms.

Ms. Price is a Wall Street Journal editor in South Brunswick, N.J. Email patricia.price@wsj.com.