What is green hydrogen, and how green is it, anyway?

Hydrogen, specifically "green hydrogen," has been making headlines in Nova Scotia in recent months as a handful of companies continue pursuing energy projects.

But the term is fairly new to many.

Even Nova Scotia's minister of natural resources and renewables, Tory Rushton, said in August that "green hydrogen wasn't in my vocabulary a year ago."

So, what exactly is green hydrogen? And how green is it, anyway?

Green hydrogen is hydrogen that's produced from renewable energy, such as wind or solar power.

It is produced using a process that may take you back to high-school science class.

An electric current is passed through water, which is comprised of two hydrogen atoms and one oxygen atom. That process, called electrolysis, separates the hydrogen atoms from the oxygen atom.

In green hydrogen production, the source of the electrical current must come from a renewable source; otherwise, it is not considered "green."

The hydrogen gas is then captured and can be stored for later use or channelled into a fuel cell to produce electricity. Some uses of green hydrogen include powering vehicles, planes, ships, long-haul freight and production of ammonia for fertilizer.

Green hydrogen is viewed by many as an environmentally friendly alternative to fossil fuels because it is generated using renewable sources such as wind energy, so it doesn't produce harmful emissions and can be stored.

But some analysts caution there are caveats.

The first step in any green energy strategy should be efficiency — to use less energy, says Gretchen Fitzgerald, the national programs director for Sierra Club Canada.

"The best power plant is the one you don't have to build," she says.

The second step should be using the energy from renewables as a direct power source, rather than converting it to other products such as hydrogen, Fitzgerald says. Every time energy is converted from one form to another, it loses efficiency.