Is Gas the Future?
How should we heat our homes, not just now, but in 10, 20 or 30 years? Energy expert David Hilton believes that staying with the gas grid - with promising options for delivering low-carbon gas or even hydrogen - could be the smartest way forward
Utilising mains gas could be the smartest way forward despite media headlines. Energy expert David Hilton explains why
When deciding on heating systems for our homes we are often tempted by the latest ‘eco’ products and the urge to futureproof. Sensational headlines like ‘UK gas supplies are running out’ are rallying the common perception that gas is going and we should focus on electric-based heating systems instead. But what’s the truth behind the headlines?
WHERE ARE WE AT THE MOMENT?
In real terms the electrical grid simply does not have the capacity to supply enough power to heat all UK homes. However, gas in its current form is getting more difficult to find, and its embodied carbon footprint will not help with meeting any of our carbon reduction targets. So what’s next?
The gas grid is currently around 284,000km long and supplies gas to about 23.4million customers, which is around 80% of UK households. Around five years ago, government policy papers called for a large switch from gas boilers to (electricity-powered) heat pumps. But although electricity is easy to generate from renewable sources, it is far more expensive and difficult to store, especially given the erratic spikes in consumer demand. For heat pumps to be successfully rolled out at that scale, the UK would need to more than double its generation capacity and also invest significantly in storage capacity for times when demand is high.
On the other hand, the gas grid can already meet the variable demands, especially during winter, which makes it a very good and functional asset. The real answer is therefore fairly straightforward: if we want to reduce carbon then we don’t need to switch away from gas. We just need cleaner gas. ➤
WHAT Is CLEANER GAS?
There are a number of potential low-carbon solutions being considered now, such as biomethane and hydrogen.
Natural gas is currently still the cleanest of the fossil fuels and in the UK it still also compares very favourably against many heat pump technologies, due to the carbon intensity and transmission losses of the electrical grid. Our natural gas is mainly made up of methane, and although it is a fairly clean fuel, it still releases carbon when burned. So, low-carbon alternatives could dramatically cut the emissions and add life to the existing gas grid.
Low-carbon gas can be collected from organic waste in a number of different ways. Anaerobic digestion is the decomposition of the organic waste in an oxygen-free environment; the methane produced is then put into the gas grid for use in homes. This biomethane is still a carbon-emitting gas but it is considered low carbon because it is produced from organic waste that would have broken down anyway and released its carbon emissions naturally. There are
currently around 90 biomethane plants already injecting gas into the grid, but with limited supply of appropriate and sustainable organic feed, the potential for this technology is limited to around 5% of the current gas demand.
Cadent (formerly National Grid) has also tested the first BioSNG (synthetic natural gas) plant in Swindon. BioSNG can be used in the same way as natural gas. It is still methane but because it is developed through gasification, a much wider range of waste can be used, including household rubbish, that would normally have gone to landfill. The project partners report that the BioSNG has a carbon footprint that is 80% lower than natural gas, depending on whether the waste is biological or synthetic (plastic). If this is then combined with carbon capture and storage (CCS) – a technology that captures 90% of the carbon dioxide emitted from fossil fuels – Cadent claims that BioSNG could actually be carbon positive with reductions of around 190%. They also suggest that, long-term BioSNG could meet around 33% of the UK’s heating demand if most of our waste is used for production.
There’s also a case being argued that it could be time to move away from methane for heating altogether and switch to hydrogen, which would result in a 75% reduction in carbon emissions. Hydrogen-powered heating is not new. Natural gas has only really been used since the 1960s. Before this, the country used what was referred to as ‘town gas’ – largely hydrogen with a small amount of methane and CO2 – for almost 100 years.
Hydrogen is not explosive, poisonous or radioactive and only emits water and heat when it’s burned, but its high temperature production is carbon intensive and it relies on CCS to be classed as low carbon. Hydrogen appliances would be almost identical to the products that consumers are familiar with (i.e. our natural gas boilers), and as hydrogen doesn’t produce CO2, the poisoning risk is also eliminated. Once the UK’s iron gas pipes have been replaced (by 2032), then around 90% of the grid would be suitable for hydrogen.
However, significant investment in hydrogen production, storage and CCS infrastructure is needed. The good news is that the government has committed millions of pounds, and many manufacturers are developing demonstration appliances that can use hydrogen.
In the shorter term, hydrogen could be injected into the current grid with concen- trations of up to around 20% by volume, which can be tolerated by most existing natural gas appliances (but not things like gas turbines and industrial machinery). However, this would only realistically result in around a 6% reduction in emissions.
A move from natural gas to hydrogen has many advantages and is technically possible, albeit with administrative hurdles and much research required to prove its safety. The way we are metered and billed, for instance, will need to change, as we are currently billed on the amount of energy we use rather than the actual volume.
The government and industry are all waiting for the results of the low-carbon gas trials, and any programme of change to the gas grid would need to be initiated by the mid 2020s if it is to be completed by the target deadline of 2050.
Low carbon changes can be made, so if you’re on mains gas my advice is still to use it — or to connect to it if you’re building a new home. A move away from the gas grid would not realistically be futureproofing at all and could actually be a move in the wrong direction. Electricity-producing renewables certainly have their place, particularly in well-insulated, airtight homes, but the greening up of the gas grid is the most feasible and also most likely solution to heating the existing UK housing stock by 2050 and beyond.
“If you’re on mains gas, my advice is still to use it”