On the day he announced hundreds of new North Sea oil and gas licenses prime minister Rishi Sunak told reporters that producing natural gas in the UK is “better for the climate” than importing it from abroad.

He said that’s because it’s “far better to have it here at home rather than shipping it here from halfway around the world with two, three, four times the amount of carbon emissions versus the oil and gas we have here at home.”

Grant Shapps, the secretary of state for energy security and net zero, repeated the claims today on BBC radio.

So is the government right that natural gas produced here is less polluting than imported gas?

FactCheck takes a look.

The claim

Mr Sunak’s figure comes from the North Sea Transition Authority (NSTA) a government-owned company responsible for regulating oil and gas in the North Sea.

The carbon emissions of different energy sources can be measured in the number of kilos of carbon dioxide they release per “barrel of oil equivalent”, or BOE.

Recent NSTA research said that the average carbon intensity of imported natural gas for each BOE is 79kg, compared to 21kg for North Sea gas from the UK.

That seems to make imported gas nearly four times more polluting than our domestic supply, as the prime minister said.

The main reason for this is that some gas imports come in the form of Liquified Natural Gas (LNG), where gas is extracted from the ground and put under huge pressure to turn it into a liquid before it’s transported across the world.

This whole process takes a lot of energy and is, therefore, more polluting than using the gas immediately.

The NSTA said this meant that producing gas at home rather than relying on imported LNG is the “better path to net zero emissions”, and suggested that producing gas here would lower the UK’s greenhouse gas emissions.

What the research doesn’t say

But there’s a catch. The NSTA research doesn’t account for the emissions caused by burning the gas, which make up nearly all of the carbon footprint.

The emissions from the production, processing and transport of gas are very small compared to the emissions from actually using it.

The International Energy Agency says that the combustion of natural gas is around 320kg per barrel of oil equivalent. That’s a lot larger than the 21kg it takes to extract the gas in the UK, or the 79kg from extracting, processing and transporting imported gas.

When we factor in the 320kg, the gap between imported and UK-extracted gas becomes relatively much smaller — 399 kilos of carbon per unit, versus 341kg. On that basis, imported gas is about 17 per cent more polluting than gas from the North Sea — not “four times” worse, as Rishi Sunak claimed.

The UK’s statutory climate advisor, the Climate Change Committee, has said that the overall net impact of more UK oil and gas exploration is likely to mean higher overall global emissions.

We put our analysis to the government who told us: “The Prime Minister was completely correct with his statement, based on research, which shows domestically produced gas is on average four times cleaner than imports.

“The process of extraction, combined with the emissions produced by the transportation of imported gas, mean considerably higher emissions than when gas is produced in the UK and these processes are not needed.”

FactCheck verdict

Rishi Sunak claimed that extracting more gas from the North Sea is “better for the climate” because the alternative — importing gas from abroad — is “four times” more polluting.

It’s true that the extraction, processing and transport of imported natural gas is four times more carbon-intensive than the extraction and transport of gas taken from the North Sea.

But when we account for the massive carbon emissions caused by burning the gas, the difference between the two sources becomes proportionally much smaller. Using figures from the International Energy Agency, we estimate that imported gas is about 17 per cent more polluting overall than North Sea gas — not “four times”, or 500 per cent worse, as Rishi Sunak claimed.

And of course, the more gas the world extracts — wherever it’s from — the more carbon will be emitted into the atmosphere.