Know your Net Zero from your NETs and BECCS

The history of and debate over Net Zero:
In 2015, nearly 200 countries signed up to the Paris Agreement committing “to limit the global temperature increase in this century to well below 2 °C above pre-industrial levels, and pursuing efforts to limit the temperature increase to 1.5 °C”.

Calculations were made of the maximum amount of Carbon Dioxide (CO2) and equivalent gases, (collectively known as CO2e) that could still be emitted to have a chance of remaining within this temperature range and this “Carbon Budget” allocated fairly amongst signatories to decide how and when to restrict their own emissions.

Many scientists believe that reducing emissions to zero, as soon as possible, should be the prime target. However during negotiations in Paris, it was believed that this “Zero Carbon” policy would result in significant downturns in the economies of the richest countries and so, to reach consensus, countries were permitted to include methods to remove CO2 from the atmosphere. In other words, with a carbon budget of 1 tonne, you can emit 1.2 tonne as long as you can find a way to remove 0.2 tonne.

So when our government legislated for “Net Zero by 2050” the UK could still be emitting say 100 Mt (million tonnes) of CO2e per annum in 2050 (mainly from agriculture and aviation) and so must plan to remove at least the same amount to get to Net Zero.

Many scientists consider the Net Zero (also known as Carbon Neutral) methodology to be false accounting in that by anticipating removals, especially after 2050, we risk exceeding carbon budgets before 2050, causing spikes in temperature and irreversible climate tipping points thus making the later removals irrelevant. There is also concern that by providing false hope over the ability to remove emissions in the future, less effort will be made to reduce emissions now. The conclusion of a study by Lancaster University in 2019 was that trying to synchronise both emission reductions and removals, over thirty years, into a single Net Zero target was unrealistic and that the two routes should be approached separately, aiming for the best achievable result in each.

The calculation of fair national shares of the global carbon budget has also generated disagreement in that richer nations, like the UK, will calculate their share without recognising significant historic emissions still present in the atmosphere, leaving unfair shares for poorer nations that still need to emit to grow their economies.

“Removals” is the generic term for removing emissions and this is also referred to as Carbon Dioxide Removals (CDR). There are many different ways in which removals can be achieved and they can be broadly categorised as either Nature-based or Engineered.

Nature has several ways to draw down carbon dioxide from the air and store it, either short or long term. The best known is in plant growth. Trees and other land or sea plants use photosynthesis to draw down CO2 from the air for growth and to pass some to the soil or seabed as carbon as they decay. The short term cycle involves the trees and plants dying and decaying, with a release of CO2 back into the atmosphere, whereas peatlands, for example, can remove and store carbon for indefinite periods and, in the past two hundred years, we have burned such long term carbon as coal, oil or gas.

The process of natural storage, in say the soil, is known as “sequestration” and where it is stored is known as a carbon “sink”.

The government and its advisors, The Climate Change Committee (CCC), are therefore anticipating extensive tree planting and peatland restoration in the next few decades with the CCC’s 2050 net zero plan forecasting an extra 39 Mt of CO2e per annum being sequestered by natural processes in 2050.

On paper and in trials, industry has started to explore engineered ways to remove CO2 and store it. This is known as “Carbon Capture & Storage” (CCS) and the various methods of doing it “Negative Emission Technologies” (NETs).

The main group of NETs are “Bio-energy with Carbon Capture & Storage” (BECCS) which involve the creation of bio-energy from organic matter (biomass) and capturing/storing the resulting CO2, usually by pumping it into exhausted gas and oil wells. BECCS was the technology agreed outside the main Paris agreement as being the economically acceptable way to meet “Net Zero” targets.

There are several BECCS technologies however the main one involves burning wood for power. The UK’s Drax power complex provides about 6% of the country’s electricity and, moving away from coal and gas, currently burns about 20,000 tons of wood pellets a day, sourced mainly from North American forests. It has started trial CCS facilities onsite capturing about 400 tonnes of CO2 per annum with plans to eventually capture and store 16 Mt per annum.

The principle behind this is that, growing, burning and capturing the CO2 from trees provides greater carbon savings than just leaving them to grow, die and decay. There are however doubts over relying upon unproven technology, the availability of sustainable sources of wood, conflicts with land for food production and the fact it takes years for new tree plantings to grow for harvesting. It is also the case that not all of the CO2 from the transporting, processing and burning of the trees, can be captured.

On the plus side the capturing and storage process itself takes energy and so the exhaust heat from the power station can provide this.

The CCC’s 2050 Net Zero plan involves engineered removals of about 58 Mt of CO2e per annum by 2050, with the various forms of BECCS providing 53 Mt and the other 5 Mt coming to scale in perhaps twenty years in the form of “Direct Air Capture & Storage” (DACCS), in which CO2 is removed from the air and stored.

In simple terms offsetting is the practice in which, instead of reducing your own emissions, you pay someone else to reduce theirs. For example, you can still do this when you fly, by paying for tree planting to offset your emissions.

In the majority of cases offsetting has involved rich industries and individuals paying their poorer cousins but it has also been done on a national basis with one country investing in the NETs of another or, as indicated by the CCC, rather than struggling to reduce its own emissions, the UK might instead increase foreign aid to assist other nations to reduce theirs.

This practice may well have been an incentive in the past for industries and nations but the majority of countries have signed up to the Paris agreement and, with fair carbon budget allocations, each can look after their own, in other words it is fallacious to pay for someone to do something they were bound to do anyway and, in order to reduce emissions as fast as possible, the best approach, as set out in the Paris Agreement, is for the rich to reduce their own emissions and assist the poor to do the same.

See also The Climate & Ecological Emergency Bill

Wildlife Warden February Newsletter

Thanks to all wardens for the hard work you have put into the scheme during these difficult times. The scheme is constantly growing and moving in the right direction. We have created a subdomain on the ACT website for the Wildlife Warden Scheme. It is still in development, but it already contains lots of useful information: 

The picture at the top is my most recent wildlife sighting – a barnacle-looking gall found on bramble. It may not be the most beautiful sighting, but I found it fascinating. I believe they were created by Diastrophus rubi, which is a small parasitoid wasp. A gall can contain up to 200 larvae, each in an individual cell.

We have been finding out a lot about seagrass (eelgrass) habitats. There are two species of seagrass (Zostera noltei and Z.marina), which provide an important habitat for a wide range of species, and help to stabilise the seabed, clean surrounding seawater and absorb vast quantities of CO2.

Unfortunately, seagrass is critically endangered. It is threatened by high nutrient levels (mainly from fertilisers and animal waste), damage from anchors and propellers, disease, and destructive fishing practices. There is anecdotal evidence that seagrass probably existed in the Teign Estuary prior to the 1990s, but it is no longer present. Seagrass in the Exe Estuary has expanded in recent years and can be found near Dawlish Warren, Exmouth and Lympstone.

Read more here

Wood burning stoves and air pollution

Wood burning stoves are in the news. They make a significant contribution to air pollution according to a recent government report. Wood burners and open fires together account for more than one-third (38%) of the tiny particles known as PM2.5 that are among the most damaging types of emissions for human health. That is more than any other source. Road traffic, by contrast, accounts for only 12%.

I’m not sure what to make of this. I like to fire up our stove on cold days, to supplement the oil-fired central heating, and we are thinking of adding a second stove elsewhere in the house to reduce our reliance on oil. Surely it is better to burn wood than fossil fuels? 

Well it’s not that simple. Wood is a renewable energy source as burning it is carbon neutral and doesn’t increase carbon dioxide emissions. But those PM2.5 emissions are a problem, both inside and outside the home. Open fires are worse than burners on that front, but many burners with doors are poor too. A recent study by the University of Sheffield showed that people who open the door to load a stove twice or more in an evening are exposed to pollution spikes two to four times higher than those who refuel once or not at all.

The problem is compounded by burning the wrong type of wood. Emissions from wood treated with chemicals or containing glue are seriously carcinogenic. Wet wood is also more polluting because it produces more smoke. A ban on sales of wet wood for households came into force in England in February.

Biomass boilers tend to be less of a problem than wood burning stoves, especially those that burn wood pellets. They are also more an informed choice than a nice-to-have accessory as you can’t sit around them enjoying the comforting warmth and glow.

I’m happy to take the indoor pollution risk of using a wood burner. But what about the particulates escaping up the chimney? Is air quality in Newton Abbot affected by that? Judging by a pollution map based on the National Atmospheric Emissions Inventory, the answer is yes. Domestic wood burning is the biggest source of air pollution due to PM2.5 in all the local towns.

This surprising fact has to be seen in the context of the huge reduction in air pollution over the past 50 years and the way the government measures it. Annual emissions of PM2.5 have fallen by 80% since 1970, mainly due to the falling use of coal and higher emission standards for transport and industry. The decline has levelled off in recent years though, as decreases in emissions from some sectors are largely offset by increases in emissions from domestic wood burning and use of biofuels by industry.

Wood burning stoves have become fashionable in recent years. They have also become more efficient and less polluting (in terms of outdoor pollution at least). The government’s report assumes stoves in use are mostly of the old polluting type, and that they are being used for 40 hours a week in winter and 20 hours a week in summer. This is based on a 2015 survey that also forms the basis of the NAEI. The government admits its estimates could be wrong by a factor of 10, so wood burning stoves could be making a much smaller (or larger) contribution to air pollution than the 38% attributed.

Whatever the numbers, Gary Fuller, an air pollution scientist at Imperial College and author of ‘The Invisible Killer – the rising global threat of air pollution and how we fight back’, is clear that burning wood, especially as a fashion statement, is not acceptable. In an interview with Environmental Protection Scotland he said even stoves that meet the eco-design standards that will apply from 2022 “emit the same amount of particles as the emissions from six heavy goods vehicles”.

That doesn’t sound like a neighbourly thing to do, even in my semi-rural village. In a city, it is definitely hard to justify when we know that air pollution is a killer. So my search for a clean alternative to burning oil to heat my house is leading in the direction of a heat pump, although that will be more expensive to install and run than another wood burning stove. If I was a more cynical person, I would suspect this demonisation of wood burning stoves to be a campaign aimed at prolonging our reliance on fossil fuels. That’s just mad though, isn’t it?