United Kingdom's coal-free days brought to you by natural gas

The United Kingdom just broke records for the number of days it went without any coal-fired electricity — thanks largely to natural gas.

Driving the news: The 18-day streak was snapped late yesterday, according to the UK's electricity operator. Coal has historically been the nation's dominant electricity source. Natural gas burns 50% less carbon emissions than coal. Due to several factors — notably a carbon price policy implemented in 2013 — the UK’s coal use has plummeted, natural gas has risen to make up most of the difference and emissions have dropped.

The big picture: Natural gas is controversial in the world’s energy and climate debate. It’s still a fossil fuel, but the cleanest-burning kind, so when it’s displacing coal, it reduces greenhouse gas emissions as the accompanying chart shows. The experience in the U.K. shows what an outsized role natural gas can fill in countries seeking to reduce or eliminate coal altogether.

The intrigue: Via The Guardian: "Coal has been used for electricity generation since 1882, when a plant opened in Holborn, London. However in 2018 the fuel made up just 5% of Britain’s electricity generation, a big decline from about 40% in 2012, according to figures from the Department for Business, Energy and Industrial Strategy."

• Natural gas has the largest share, around 42% of the power mix.

Yes, but: Longer term — we’re talking many, many decades — remaining heavily dependent on natural gas is likely going to make it a lot harder (some experts suggest impossible) to cut greenhouse gas emissions to a level scientists say will avert the worst impacts of a warmer world.

• That’s because, while cleaner than coal, natural gas still emits greenhouse gasses. To the extent it remains in place for decades, that means less zero-emitting renewable energy.

• Technology capturing emissions could allow for aggressive gas usage in a world drastically reducing emissions, but it's expensive and not broadly employed.

What we’re watching: The International Energy Agency, an inter-governmental research agency based in France, is set to issue a study in July looking at fuel switching between coal and natural gas and the latter’s role in a transition to cleaner energy.

Go deeper: Tale of four countries: The world’s evolving energy mixes