What decarbonizing really requires

It is tempting to picture decarbonizing as one big purchase. Build enough solar panels and wind farms, swap the old plants out, and the problem is solved. But a solar panel does not make steel. It does not pour cement, or fly a plane across an ocean, or push a container ship through the Pacific. Clean electricity is most of the answer — and then it runs into a wall of things that don’t run on electricity at all.

So the honest question is not “can we make clean power?” We can. The question is: what would it actually take to cut a whole economy’s emissions to near zero? The answer has two very different halves.

The playbook: electrify everything you can, then clean the electricity

Most of the plan is a single move repeated everywhere. Take a thing that burns fuel, and make it run on electricity instead. Then make sure that electricity is clean.

Those are two jobs that have to happen together. Clean the electricity — more wind, solar, storage, plus firm low-carbon power you can switch on (nuclear, hydro) for when the weather doesn’t cooperate. And switch the end uses — the cars, the furnaces, the home heating — from burning their own fuel to drawing from that clean grid.

Done alone, neither works. A clean grid powering nothing new just leaves petrol cars still burning petrol. Electric cars charged from a coal plant just move the smokestack. You need both ends.

Here is the part that surprises people. Electrifying often uses less total energy, not more. Recall the efficiency lesson: an electric motor turns about 90% of the energy it draws into motion, while a petrol engine wastes about three-quarters of its fuel as heat and gets maybe 25% to the wheels. Swap the engine for a motor and the same trip needs far less energy at the source. The same logic runs through heat pumps replacing gas boilers. So this half of the transition isn’t only cleaner — it’s leaner.

A large chunk falls to this — but not all of it

Put rough numbers on where an economy’s emissions come from. These are approximate, and they vary by country, but the shape holds. Of global emissions, very roughly: electricity and heat are about a quarter. Transport is about a sixth. Industry — including steel and cement — is about a fifth. The rest is buildings, agriculture, and other sources.

Now look at what the playbook reaches. The electricity slice — clean the generation, done. A big part of transport — road vehicles become electric. A big part of buildings — heat pumps instead of gas. That is a large fraction of the total, cut with tools that already exist and already work.

But notice what’s left standing. A meaningful slice — very roughly a third of emissions — sits in places where “just electrify it” does not work. That slice has a name.

The hard-to-abate sectors

Some processes resist electricity because they need something electricity does not easily give. There are three flavours of hard.

The first is extreme heat. Some industrial furnaces run far hotter than an electric element comfortably reaches. Steel is the headline case: a blast furnace needs intense heat and carbon as a chemical ingredient — the carbon pulls oxygen out of iron ore. Electricity can supply heat, but not that chemistry, not the old way. (New methods using hydrogen instead of carbon exist and are being scaled — but they’re a whole new process, not a plug swap.)

The second is chemistry that releases carbon no matter the energy source. Cement is the brutal one. Making cement means roasting limestone, and limestone is a carbon compound — heating it releases CO2 from the rock itself, separate from whatever fuel you used. Run the kiln on perfect clean electricity and the limestone still gives up its carbon. The emission is baked into the recipe.

The third is energy that must be incredibly dense and light. Aviation and shipping need fuel that packs huge energy into little weight — the reason a jet uses kerosene and not batteries. Batteries are far too heavy for a long flight; the plane couldn’t lift its own power source. This is the density lesson from earlier, now as a hard limit.

For these, the answer isn’t a swap. It’s new processes still being worked out: green hydrogen, capturing the CO2 at the smokestack, synthetic fuels made from clean energy. Some are close. Some are expensive. None is finished at scale.

It’s a whole-system rebuild, not a fix

Step back and the shape is clear. There is no single lever. There is an easy-ish front — power and road transport, where known tools cut deep — and a stubborn remainder — steel, cement, planes, ships — where the cuts are slow and the technology is unsettled.

That changes how to read every confident claim about the transition. “We’ve solved clean power” can be true while a third of emissions sits untouched. Progress on the easy half is real and worth counting. So is the gap. Both are true at once, and conflating them — treating the whole problem as solved because part of it is — is the most common mistake.

The transition is one connected rebuild. The clean grid, the electric car, the heat pump, the green-steel furnace, the captured cement carbon, the synthetic jet fuel — they are not separate projects competing for the headline. They are pieces of one machine, and the machine only works when the pieces fit. You live inside that machine already: the grid that lights your room, the concrete under your feet, the steel in the building, the plane that carried something you own. Seeing how tightly those are bound is the start of holding any “one weird fix” claim a little more loosely — because there isn’t one, and the people who say there is have usually only looked at one piece.