Gas has for the past two hundred years been a fuel that has offered the UK flexibility – be it for street lighting; industrial processes; power generation or heat demand. Gas in the UK used to be manufactured, when it was “town’s gas” and then from the 1960s converted to “natural gas”. As a result of its abundance, the UK has the world’s leading gas grid infrastructure in place, directly supplying the energy to heat 85 per cent of UK homes. The next century could be about “green” gas.

Gas currently accounts nearly 50 per cent of non-transport UK primary energy needs – for power generation and heat. If offers the flexibility to back-up renewables (wind and solar) when our weather patterns dictate and can be used as baseload too, if nuclear becomes unaffordable. But the environmental cost is that gas accounts for 40 per cent of the UK’s greenhouse gas emissions. This needs to change and green gas is therefore central to the UK’s future energy mix.

When it comes to heat, gas is the UK’s fuel of choice, and for good reasons. The much-used graph (below) by Robert Sansom of Imperial College, demonstrates better than words can, the challenge. Heat demand is seasonal, no surprise there, but its peaks during the winter either need to be met by supply or people will go cold. The latter is no policy prescription that any sensible politician advocates. So having the energy, in whatever shape, available at short notice to meet peak demand, whilst not having supply sitting idle for much of the year has to be the energy outcome of choice. In 2010, the Coalition Government suggested heat demand could be met by switching from gas to an all-electric solution. The same graph also shows the levels of current electricity demand. As you can see, whilst there is variation across seasons, days and hours the peaks and troughs are nowhere near as great.

See figure One: above

So whilst baseload power generation, either through nuclear or renewables (with gas backup) can cater for the UK’s electricity demand, building additional generating capacity to deal with heat demand as well, is simply unaffordable. Even after an major energy efficiency retro-fit in 26 million homes and businesses, it is estimated that to meet peak heat demand would require the equivalent of 30 new nuclear power stations, or 100 additional inter-connectors, 60,000 additional wind turbines (with back up) or every UK home to have solar PV (again with back up). On top of that, the UK’s current distribution networks could not cope with such extra demands on them. A switch from gas to electric requires householders to fit alternative heating systems – yes that means ripping out gas boilers, pipes and radiators as these systems are different to those using electric heating appliances. These are costly changes that consumers can ill-afford. A recent study of Bridgend, produced by Wales and West Utilities, suggest that 81 per cent of households simply do not have the cash at their disposal to make that investment, without massive subsidies. The UK would also need to be entirely re-wired, from power station to the home to keep people warm and meet the UK’s climate change obligation. That cost would also be borne by the consumer (voter). E&Y estimate the current additional cost per household, to increase sub-station capacity is £290 (urban) and £390 (rural).

All the time, underground and becoming redundant with an all-electric scenario sits the UK’s gas distribution grid. Developed over the years, updated with PPE (the yellow plastic stuff you see) rather than iron pipework, the all-electric scenario renders this valuable piece of UK infrastructure unnecessary. And yet, it currently meets the heating needs of 85 per cent of UK homes – politicians meddling with this do so at their peril.

So if gas can be supplied to the vast majority of homes, meeting peak heat demands, in a cost effective manner then surely it makes sense to see how this source of energy can become “green”.

There is no definition of what “green” gas is; indeed this is part of the attraction in that there is no winner or silver bullet but instead a range of green gases. Perhaps “low carbon” gas is a better description in that it is what it says; it has lower carbon dioxide emissions when used compared to natural gas (methane). As an aside, on a “well-to-home” basis, natural gas carbon emissions vary – primarily due to the transportation process used – with UK sourced natural gas having half the carbon intensity of LNG imported from Qatar and nearly a third the carbon intensity of gas sourced from Russia.

First off the blocks is biomethane. This is the gas captured from waste processing, typically anaerobic digestion. The technology is proven, it has worked for years. In my former Worcester constituency, for years the warm water of the swimming pool in St Johns was heated by the gas from the neighbouring sewerage plant. Anaerobic digesters are increasingly commonplace in rural areas as the farming industry uses the non-domestic Renewable Heat Incentive to support generation of biomethane. The gas generated is then used locally, often to generate electricity which can be fed into the grid. Companies like Severn Trent have taken a further step, and clean up the biomethane to inject the “green” methane into the gas grid at their sewerage works in Minworth, on the outskirts of Birmingham. By the end of 2015, some 2TWh/annum was injected into the gas network, equating to around 155,000 homes.

Rural homes have often been seen as the obvious target for alternative energy sources. But industry has responded by developing biopropane as an alternative to LPG used in around 170,000 UK homes and businesses that are off the gas grid. The biopropane is made from a waste product, hence its “green” qualification and it requires no change to either the boiler or heating system as the gas is identical in its composition. Calor plan to start marketing biopropane in 2017 to their LPG customers. EUA have calculated that carbon emissions could be cut by 83 per cent if consumers switch from LPG to biopropane.

Following on from biomethane, is Synthetic (or Substitute) Natural Gas (SNG). This is a methane-based gas, created artificially rather than being extracted from the ground. It achieves “green” status because it uses waste materials, usually sent to landfill or incineration, to create the gas. The process is technically complex, it involves Advanced Plasma technology in effect heating the waste to very high temperatures, generating gas that is then captured for use. Ofgem have recently awarded National Grid funding to develop a commercial scale plant in Swindon, having seen the success of smaller trials of the technology. The alternative use of waste gives the gas its “green” credentials. The Swindon plant envisages supplying gas for HGVs but there is nothing to stop it being fed into the gas grid for everyday use once it is blended to reach the gas quality standards required.

Studies by National Grid suggest up to a third of current UK domestic demand for gas can be met from bioSNG, around 100TWh/annum. If progress towards greater energy efficiency in our homes and workplaces continues, they suggest by 2050 a 30 per cent reduction in gas demand could be achieved. This leaves around a third of current UK demand to be met from natural gas, but by 2050, this means half the UK’s domestic gas supply could be green gas.

There is an important debate around bioenergy – growing crops for energy and not food, but using UK marginal arable land, or grassland, could provide a valuable source of feedstock for bioSNG plants. Estimates vary, but 200TWh of green gas supply is at the more prudent end of the scale.

A typical bioSNG plant is around half the size of a local authority household-waste incinerator, for the same volume of waste is uses. Its emissions are cleaner; it will last 25 years and create around 100 jobs in the construction phase and permanently employ around fifty skilled engineers to run it. It provides for more jobs than landfilling does and the UK would be using its waste and not in some cases exporting it!

Work undertaken by the Future Energy Scenario team at National Grid, suggests that any outstanding requirement for natural gas to meet domestic demand would meet our 2050 climate change obligation of an 80 per cent reduction in greenhouse gases. The only decisions the UK needs to make are how they use the green gas, and where do they get the natural gas from (but that’s another issue).

But what if the UK wants to go greener? What if the above estimates are too optimistic, how can we keep homes warm and the planet safe? So next in the queue, but not last, is hydrogen.

Hydrogen is currently produced from natural gas using Steam Methane Reforming, where the carbon can then be captured. The beauty of using hydrogen is that when the gas is combusted it does not give off carbon dioxide. It is the ultimate green gas. What’s more, it can be produced using the process of electrolysis, from excess wind power at a time the electricity grid does not require its use. Hydrogen can be transported through existing PPE pipes and only minor modifications required to appliances.

The question is how much hydrogen is used and in what manner? It is possible, within existing gas quality guidelines, to mix up to 2 per cent of hydrogen into the blend that flows through the gas grid. Some studies suggest that up to 20 per cent might be feasible – remember this makes the overall mix of gas “greener”. However, Northern Gas Networks are conducting a feasibility study into 100 per cent hydrogen through the gas grid. Their Leeds 21 study is arousing considerable interest within the industry on the basis that it envisages using the existing gas grid, conventional heating systems such as central heating in the home but in a completely carbon free way. The way in which the gas grid grew up from localised supply to a national infrastructure enables the potential switch to be made in an organised manner. For those of a certain age, similar to the 1960s switch from towns to natural gas. Already appliance manufacturers are discussing the implications for their products. It could well be that swapping a central heating boiler’s burner, in each home, is an affordable option compared to other means of tackling the trilemma.

This essay is not designed to reach the conclusion that one single option can solve the UK’s future energy needs, whilst being affordable and green. The reality is that a range of options is likely to provide the answer. What is essential though, is that the UK recognises the climatic challenges its geographical location burdens it with and that the existing gas grid provides a mechanism for delivering the desired outcome. Green gas, either lower carbon from source, using waste products or hydrogen offers a way forward. It means not turning our back on gas; nor limiting its use solely as a short-term solution.

Mike Foster, Chief Executive, Energy and Utilities Alliance

(Former Labour MP for Worcester 1997 – 2010)