I sometimes become exasperated when progress toward clean energy is measured by, say, the amount of a government tax credit for buying electric vehicles, or the the announced dates for when a state or city will reach zero carbon emissions, or whether an international agreement is signed or not. My annoyance is that while policy changes or timelines or signatures can be useful in spurring change, reaching clean energy goals requires actual physical changes in generation, storage, transportation, and usage of energy. The extent to which the needed physical changes are happening or not is literally the entire issue.
In this spirit, the McKinsey Global Institute has published a report called “The hard stuff: Navigating the physical realities of the energy transition” (August 14, 2024 ). The authors write:
This energy transition is in its early stages. Thus far, deployment of low-emissions technologies is only at about 10 percent of the levels required by 2050 in most areas, and that has been in comparatively easy use cases. More demanding challenges are bound to emerge as the world confronts more difficult use cases across geographies. Complicating the task of building a new low-emissions energy system is that it coincides with the need for it to continue to grow to expand access to energy for billions of people who still do not have it, thereby economically empowering them. This transition also needs to address rising concerns about energy affordability and security as well as the role of the energy system in ensuring industrial competitiveness. Moreover, the aspiration is for a rapid energy transition.
The report focuses on 25 physical tasks that need to happen across seven areas–some of them with technologies that are far from mature. Here’s a graphic to illustrate. The light blue hexagons still require technological progress, but face the lowest physical hurdles. The medium blue hexagons require both acceleration of known technologies and expanded infrastructure. The dark blue hexagons (12 of the 25 categories) are where “the transformation is just beginning.”

The report goes into these 25 categories in some detail. Here are some high points from the seven main categories:
—Power. Overall, low-emissions power generation capacity would have to increase about ten times by 2050. There are two Level 3 challenges: managing variability in the power system as solar and wind generate a greater share of power, and doing so in emerging power systems that need to grow particularly rapidly. The flexible capacity that would be required to manage this variability, including backup generation, storage, and interconnections of grids in different regions, would need to grow two to seven times faster than power demand, but all face barriers. …
—Mobility. The number of EVs would need to surge from about 30 million on the road today to about one billion by 2050. … Scaling EV charging infrastructure and supply chains has further to go and is Level 2. Trucking, aviation, and shipping are harder to decarbonize, given that they require traveling long distances with heavy payloads, and are Level 3 challenges.
—Industry. Decarbonization of the “big four” industrial material pillars of modern civilization—steel, cement, plastics, and ammonia—poses four Level 3 challenges, where the transformation is just beginning. …
—Buildings. Heating accounts for the largest share of buildings-related emissions. Heat pumps are already established technologies and perform well, but … [m]ore demanding, and therefore Level 2, is managing a potential doubling or tripling in peak power demand in some regions if heat pump use expands.
—Raw materials. Demand for critical minerals, like lithium, cobalt, and rare earths, is expected to surge, but current supply is only about 10 to 35 percent of what would be needed by 2050. …
—Hydrogen and other energy carriers. New energy carriers would be needed to serve as alternative fuels and feedstocks for industrial processes. One option is hydrogen, which faces two Level 3 challenges. First, the hydrogen molecule goes through many steps and therefore energy losses before it can be used; these would need to be minimized and weighed against its advantageous properties. Second, hydrogen production and infrastructure would need to expand hugely. Few large-scale low-emissions hydrogen projects are currently operational. …
—Carbon and energy reduction. Alongside measures to substitute high-emissions technologies for low-emissions ones, reducing the amount of energy consumed and the emissions of current technologies would also be needed. … Carbon capture from new “point sources” such as cement could be three times harder—and costlier—than for less demanding current use cases, and removing carbon from the atmosphere through direct air capture could be even more costly.
The first international treaty to address greenhouse gas emissions was signed at Kyoto 27 years ago, back in 1997. Frankly, as I think about the challenges listed in the McKinsey report and the current state of world energy production as a whole, the rough estimate that the 10% of easy progress has been made seems too optimistic. To put it another way, the announcements of timelines and treaties about zero-carbon or low-carbon energy, or about government spending and subsidies toward that goal, looks wildly optimistic compared to the amount of actual physical change that has happened. The decisions made back in the 1980s for countries other than France (!) to steer away from zero-carbon nuclear power, and even more the decision to back off from innovating that area, are now coming home to roost.






