why is green hydrogen more expensive than normal hydrogen

Ordinary hydrogen is made from natural gas in a process that has been refined for decades. Green hydrogen needs a large electrolyser and a great deal of cheap electricity, and the machine only pays for itself if it runs many hours a day. Where renewable power is very cheap the gap narrows. Where power is scarce or costly it stays wide.

is hydrogen safe to use

Hydrogen is handled safely in industry every day, though it behaves differently from other fuels. It is very light, so outdoors it rises and disperses quickly instead of pooling. Its flame is almost invisible in daylight, so leak sensors are standard rather than optional. Indoors and in tunnels it needs ventilation designed for it.

can hydrogen replace petrol in cars

It can, and a few models are sold, but the sums are unkind. A battery car uses most of the electricity it is given, while a hydrogen car loses much of it in making, compressing and converting the gas. Hydrogen looks better for heavy trucks, ships and machines that must refuel fast and carry a lot. For an ordinary car a battery is usually the cheaper answer.

how much water does green hydrogen need

The chemistry alone locks about nine litres of water into every kilogram of hydrogen. Real plants use more, because the water has to be purified first and some is lost. That is small next to farming, but it is not nothing in a dry region. Coastal projects usually plan to desalinate seawater rather than take fresh water.

What is green hydrogen?

Think about charcoal. Nobody digs charcoal out of the ground. You burn wood in a slow fire to make it, and you lose energy doing so. What you get back is easier to carry, easier to store, and it burns hotter in a small stove.

Hydrogen works the same way, with electricity in place of wood. You spend power to make a fuel you can move, keep and use later.

Green hydrogen is the version where the power comes from the sun, the wind or a river. Everything else about the gas is identical. The word green describes the electricity, and nothing else.

Why hydrogen at all

Hydrogen is the lightest element there is. It burns easily. It will also react inside a fuel cell, which turns it back into electricity, and the only thing leaving the fuel cell is water.

Two properties shape everything. By weight, hydrogen holds about three times the energy of diesel. By volume it holds very little, because the gas is so thin. Almost every difficulty with hydrogen grows out of that second fact.

There is one more reason to care. Some industries cannot run on electricity alone. They need a chemical reaction, a very hot flame, or a molecule to build with. Hydrogen is the cleanest candidate for several of those jobs.

How green hydrogen is made, step by step

Build solar panels, wind turbines or a hydro plant, and wire them up.
Clean the water. The machine needs water close to pure, so seawater or river water is treated first.
Pass electricity through that water inside a machine called an electrolyser. The current splits each water molecule apart.
Hydrogen gas collects at one electrode. Oxygen collects at the other and is usually let go.
Dry the hydrogen and pack it into a pipe, a tank, or a chemical such as ammonia.
Ship it, or better still, use it close to where it was made.

The chemistry sets a floor under the water use. Every kilogram of hydrogen locks up about nine litres of water, and a real plant needs more, because cleaning the water wastes some. Therefore water supply decides where these plants can stand. Coastal projects usually plan to take the salt out of seawater first.

What the colours mean

The colours are labels people agreed on. The gas itself is the same in every case.

Green. Made by splitting water with renewable electricity.
Grey. Made from natural gas by reacting it with steam. The carbon dioxide goes into the air. Most hydrogen made today is this kind.
Blue. The same as grey, with much of the carbon dioxide caught and stored. How clean it is depends on how much really gets captured.

Other colours cover other routes, and the list keeps growing. Ignore the paint chart and ask one question instead. Where did the energy come from, and what happened to the carbon?

Where hydrogen genuinely fits

Hydrogen is already an industrial raw material. That is the strongest case for it.

The largest use is fertiliser. Ammonia is made from hydrogen and nitrogen, and ammonia feeds a large share of the world’s crops. Today that hydrogen comes mostly from natural gas. Swapping in green hydrogen cuts the emissions without rebuilding the factory.

Refineries use hydrogen too. Steel can be made by using it to strip the oxygen out of iron ore, in place of coal. Ships and some heavy trucks may run on hydrogen or on fuels made from it. And a grid full of wind and solar needs somewhere to put a windy week of surplus. Batteries do that job badly over long periods.

That last case ties hydrogen to the smart grid. An electrolyser is a flexible load. It can run hard when power is cheap and stop when the grid is tight.

Where it is a poor fit

Ask one simple question of any hydrogen plan. Could you use the electricity directly instead?

For a car, you can. Put the power into a battery and most of it reaches the wheels. Send it through hydrogen and much of it is lost along the way. For heating, a heat pump moves several units of heat for each unit of electricity, while a hydrogen boiler burns its fuel once. For cooking, an induction plate needs no fuel line at all.

The rule is short. HYDROGEN EARNS ITS PLACE WHERE ELECTRICITY CANNOT GO. Where a wire and a battery will do the job, they usually do it better.

The three hard problems

Efficiency comes first. Making hydrogen loses energy. Squeezing or chilling it loses more. Turning it back into electricity loses more again. Put power in at one end of that chain and well under half comes out at the other. That is a fair price when the alternative is coal in a steel furnace. It is waste when the alternative is a wire.

Storage comes second. Hydrogen is thin. It has to be squeezed to very high pressure, chilled to about minus 253 degrees Celsius, or turned into a carrier such as ammonia. Each choice costs energy and equipment. The molecule is small enough to seep through materials that would hold natural gas, and it makes some steels brittle over time.

Safety is manageable, and it is different. Hydrogen rises and spreads quickly in the open, so a leak outdoors clears fast. However, its flame is almost invisible in daylight. Plants therefore rely on sensors rather than on eyes.

Cost comes third. Green hydrogen usually costs more than the grey kind today. It needs very cheap electricity for many hours a day, plus an expensive machine that has to run often to pay for itself.

What this could mean for Africa

The raw ingredient of green hydrogen is cheap renewable electricity. Several African countries have some of the best sun and wind on Earth. That is why so many export plans point at the continent.

Read those plans carefully. An export project needs far more than sunshine. It needs fresh water or a desalination plant. It needs a port, a pipeline or a shipping route. It needs a buyer who has signed a contract. And it needs a grid connection that does not starve local customers.

A quieter opportunity gets much less attention. Fertiliser is imported at high cost across much of Africa, and fertiliser is made from hydrogen. A plant that makes ammonia for farmers a few hundred kilometres away skips the hardest part of the export problem. That part is the shipping.

What to check

The next time a green hydrogen project is announced, ask four questions.

Where does the electricity come from, and is it new capacity or borrowed from the grid? Where does the water come from? Who is the customer, and have they signed anything? Could that customer have used electricity directly instead? A project with good answers to all four is worth watching. A project with none is a press release.

Just Out Tech explains new research in plain language. This article was drafted with AI assistance and checked by a human against the original source.