Update, 3/12/19: As a rule, I don’t edit blog posts after I publish them, but I have just been made aware of a book that deals with Russia/Europe politics in relation to gas. It’s called The Bridge: Natural Gas in a Redivided Europe. There’s a review of it here.
The less sensationalist title to this blog post should probably be something along the lines of:
UK gas supplies; climate change, decarbonisation and energy security
Last week I was giving a lecture at the Centre for Alternative Technology on gas supplies, as part of an MSc on Sustainable Adaptation in the Built Environment. The specific module is on energy provision. The backstory to the lecture is that we hear a lot about low carbon sources of electricity, and about what percentage of our electricity supplies come from renewable resources. But we tend to think much less about our other energy uses (i.e. everything that isn’t electricity). Gas is obviously one of our other major fuels, and where our gas comes from has been brought into sharp focus over the last couple of weeks owing to escalating tensions with Russia, so it seems a good moment to turn the lecture into a blog post on the subject, along with apologies for the click bait title…
I have been giving this lecture for a few years now, and generally start with a table of numbers on UK final energy consumption, and ask the students to look at the data, discuss it with each other and decide what in the table is interesting, surprising, or useful. A deliberately vague question, to give students a bit of practice at interrogating data to work out what might be important about it. Here’s the table:
For the current purposes, I’ve highlighted the numbers that I think are particularly pertinent if we’re interested in climate change and the need to decarbonise our energy use.
The first thing to notice is how reliant we are on liquid fuels for transport; we don’t need to understand what a petajoule is in order to realise that 2,433 units of a total 2,521 units used in transport being liquid fuel is a very big part of the total (96.5%). Low carbon liquid transport fuels (e.g. biodiesel) are no longer a favoured solution to this problem; the land area required to grow crops to produce transport fuel simply isn’t available. So called ‘second generation’ biofuels (which are not from purpose-grown crops) are unlikely to be available in sufficient quantities to be a major part of the solution. So in practice, our solution to decarbonising transport in the UK is likely to be widespread adoption of electric vehicles.
The next number highlighted is domestic gas use (1,623 PJ). Domestic gas use is both a very large proportion of the total gas use (looking down the gas column to the total), and also a far bigger energy consumption domestically than electricity (looking across the domestic row to the totals). Gas is another fuel that it is fairly difficult to decarbonise. Clearly a large part of the answer to the domestic gas problem is a massive improvement in building insulation and retrofit in order to decrease the total amount of gas required, which would have the added benefits of decreasing consumer energy costs and combatting fuel poverty. But the (lack of) speed at which this is currently happening suggests we will continue to have very large demand for gas for domestic use in the short to medium term.
The last bit highlighted in the table is the totals; a large part of of our total final energy consumption comes from liquid fuels and gas. The end point of all of this is the intended starting point for the lecture I give the students; if we limit our consideration to decarbonising our current electricity consumption, we are not going to solve climate change. The emphasis on current is important, because if we expect that electrification is the solution to decarbonising transport and home heating, our electricity requirements will go up, a lot!
Where our natural gas comes from
Given our current reliance on gas as a fuel source, the next obvious questions to address are who has gas reserves, and where we tend to get our gas from in the UK.
Whilst both of these images are a few years old now, the general picture is fairly obvious. Firstly, Russia is in an extremely powerful position, as is the Gulf region. Secondly, the UK does NOT get much of it’s gas from Russia. In practice, most UK gas comes from Norway, but it would be naive to think that if Russian gas availability decreased, the UK wouldn’t be affected via a massive price shock.
The amount of gas left to be extracted from the UK Continental Shelf is relatively small, and leaving aside the politics of gas, we need to decarbonise. So what are the potential sources of gas, including low carbon gas sources that might we be able to use in the UK?
Other sources of gas
The main potential sources of gas we have available to us are:
- methane produced from anaerobic digestion
- methane produced in landfill sites
- fracked gas from the UK
- synthetically produced gas (bio SNG)
In biological terms, anaerobic digestion (AD) is a process that bacteria use to generate energy in low oxygen environments. The end product these bacteria produce that we are interested in is biogas, the bulk of which is methane, with lesser amounts of carbon dioxide and a range of other gases in much smaller quantities. AD occurs in cattle rumens (which is why cattle are so bad for climate change), in the sludge at the bottom of ponds (which is often why you see gas bubbles rising through water), and it’s a process that’s been harnessed across the world to generate methane for heating and electricity production.
The signficant feedstocks for AD in the UK are biodegradable municipal solid waste (e.g. food waste collected by your local council), sewage sludge, and energy crops. The basic process is very similar regardless of feedstock; the material is shredded/mixed to ensure a consistent supply, and then supplied to a tank in which the bacteria live. The biogas is drawn off, along with the digested material, which can then be treated and used as a fertiliser.
What is done with the biogas afterwards varies. The easiest option is to burn it on site; this is how millions of households in South East Asia cook. Given its simplicity, it’s also the option chosen where there are large onsite heat demands. The next level of sophistication is CHP; combined heat and power. This process generates electricity as well as heat. The heat is generally used on site, with the electricity exported to the National Grid. The third option is to clean up the biogas to ‘gas grid’ standards and inject it into our mains gas supply networks. The cleaning technologies required to do this are fairly sophisticated, and the logistics and paperwork required to get a physical connection into the grid are not straightforward. Nevertheless, it is being done.
There is a great map here that shows the location of AD plants in the UK, and you can view the map both by feedstock and by whether they generate heat only, heat and electricity, or biomethane injection into the grid. It’s quite an encouraging picture; there are now 87 plants injecting biomethane into the gas grid, and the number is going up fairly rapidly (I would expect this number to double within the next couple of years).
So far, so good; we can use AD to generate biogas, upgrade it to biomethane and inject it into the gas grid. Unfortunately, we will quickly run into a problem with feedstock availability; there is simply no way near enough sewage sludge or food waste to substitute for our current gas use. We need to be cautious about the potential role for energy crops; whilst it is possible to grow maize and/or grass to feed AD plants, we risk creating the exact same problems as existed with first generation liquid biofuels – that is, the conflict between the need to use agricultural land to grow food for people, as opposed to crops for generation of energy. Reflecting this concern, incentive schemes for AD plants now require a maximum of 50% of the feedstock to be from dedicated energy crops. To this end, Ecotricity‘s plan for ‘green gas mills’ is problematic; the company has the laudable aim of offering both renewable gas and renewable electricity tariffs, and whilst planning permission has been granted for their first green gas mill (an AD plant using grass as feedstock) it is yet to be built.
The UK has historically been very dependent on landfill as a waste management solution, and for the current purposes these sites can be thought of as badly designed/slowly operating AD plants. The biodegradable waste that is in the landfill site is broken down by methanogenic bacteria, and the methane is piped out of the landfill and then burnt or injected into the gas grid. It’s a well regulated process and is standard practice at landfill sites. As we decrease the amount of biodegradable waste going to landfill this source of gas will also decline, and it is already a relatively small source of gas, as evidenced by UK Government data from here.
Fracked gas from the UK
Fracking the UK for gas is controversial to say the least. But we have to compare it to the current alternatives. Gas, fracked or otherwise is undoubtedly better in terms of CO2 emissions than coal, when we are considering electricity generation (burning gas has approximately half the CO2 emissions per unit of power generated compared to burning coal). And as will be clear from the above discussion of other sources of gas, we don’t have many options.
Accidental (fugitive) emissions from gas production facilities and transmission pipelines are highly disputed quantities, but are widely accepted to be higher in Russia than in the UK (e.g. see here), and so it could be argued that locally extracted gas was environmentally less damaging than imported gas. However, the quantities of gas available to us are relatively limited; around 2 years of supply at current UK gas consumption rates according to a report by the British Geological Survey for DECC. Whilst I’m relatively confident that it is possible to frack in a way that minimises risk to the local environment (particularly in comparison to other fossil fuel extraction, which is hardly a clean business), it’s difficult to see it as a long term solution to our gas supply crisis, regardless of whether you see it as a crisis of energy sovereignty or simply a way of limiting price shocks.
Synthetically produced gas – BioSNG
The UK both requires a lot of gas, and also a way of storing energy. CAT’s ‘Zero Carbon Britain‘ project is well worth a read and seeks to paint a picture of how the UK could decarbonise it’s energy use. It provides a positive vision of what the future could look like which is in definite contrast to the usual vagueness and doom mongering traps that environmentalists can fall into. As is expected, the ZCB energy supply model requires an enormous deployment of renewable electricity generation. The fact that these sources are generated intermittently creates a problem of matching supply and demand. In addition to electricity connections with other countries, a signficant element of the ZCB solution is the use of bio-SNG as a storage medium. Hydrogen is produced by electrolysis using excess electricity. The hydrogen is then converted into methane, which can then be injected into the gas grid, or burnt to generate electricity when needed. It is also possible to produce SNG by gasifying solid fuels (which could be coal, biomass or waste) to produce gases that are then converted into methane. I’ve not been able to establish the extent to which this technology is proven and/or currently available at scale.
Decarbonisation is about more than electricity supply; we need to decarbonise liquid transport fuels, and either drastically decrease or decarbonise our use of gas. When I first gave this lecture to the MSc students about 3 years ago, I was very much in favour of fracking, including in the UK. This was on the basis of four things:
- Burning fracked gas results in lower carbon emissions than burning coal.
- Environmental regulation in the UK is sufficiently robust that we would frack the UK in a relatively responsible way.
- The fugitive emissions from gas produced overseas are extremely high
- We need gas as a ‘bridging fuel’ to a low carbon future.
However, my view on this has changed somewhat in relation to points (1) and (4). Coal continues to be phased out, and we will not have coal fired electricity generation in the UK beyond 2025. The relevant comparisons of carbon emissions for electricity generation (in the UK at least) are then between different sources of gas, or with renewables, rather than with coal.
In relation to gas as a bridging fuel, this argument was heavily dependent on development of carbon capture and storage (CCS) technology; the idea being that if gas fired power stations were fitted with CCS this would reduce the CO2 emissions of burning gas to an acceptable level whilst renewable sources of electricity generation were ramped up. This idea has been modelled in detail in this report. However, the lack of progress in CCS in recent years (in the main due to the withdrawal of £1 billion of government funding for CCS projects during the comprehensive spending review in November 2015) means that we simply can’t burn gas and meet our climate change commitments, and the very limited amount of additional time that UK fracked gas would give us is not sufficient. Given the foot dragging on development of other renewables, I fear the most likely scenario is to renege on our commitments under the Climate Change Act.
If we are to burn gas, where should we get it from? We are currently importing some of our gas from the Amazon rainforest via LNG shipments from the Camisea gas facility in Peru. Whilst it’s a small quantity at the moment, is it not more responsible to frack for gas in the UK if our alternative is the Amazon rainforest? But it’s perhaps naive to think that if we don’t burn gas from the Amazon then nobody else will either. The UK is heavily dependent on gas imports. If we are ‘anti’ something like fracking, we must also be ‘pro’ something else. What is it to be? Quantified answers to this question are most welcome in the comments section on this blog…