Waste not, want not: the future of Energy from Waste
Energy Blog, 27 October 2020
Michael Ware discusses Roman rubbish disposal habits and the future of the Energy from Waste industry.
A common complaint of the grumpy middle-aged European academic is the creeping Americanisation of language. An example often cited is ‘garbage’, although the pedants amongst us know that garbage was originally an English word that went to America with the pilgrims on the Mayflower and has only recently come back to its mother country via the medium of television. I was musing on this whilst watching an American program on the Discovery channel about Roman ‘garbage’ dumps and hence the inevitable segue into a blog about rubbish.
As well as the etymology of the word garbage, my other take away from the program is how modern civilization still disposes of its rubbish in much the same way as our Italian forefathers did: we put in big holes in the ground and pretend it never happened.
Imagine 365 Wembley stadiums full of garbage
Let’s start with some startling statistics. Globally we produce about 2 billion tonnes of waste per annum and this is likely to rise to 3.4 billion by 2030. Put that a different way, it’s the equivalent of the interior space of Wembley stadium being filled from the pitch to the roof line with garbage every 17 hours. However, some 2,000 years after the Romans, we still bury about 70% of this in big holes in the ground and these big holes annually produce 1.6 billion tonnes of greenhouse gas (mainly methane and carbon dioxide).
The two alternatives to disposing of this mountain of rubbish are to either recycle it into new materials or to incinerate it to make steam and then electricity via turbines. Although both are preferable to burying, there seems to be a consensus amongst environmentalists that somehow the latter (energy from waste) is almost as bad for the planet as landfill. Now obviously one cannot generalize about every environmentalist and their views but taken in aggregate, the two most commonly articulated objections to EfW plants are that they discourage recycling and they pollute the environment.
Do EfW plants inhibit recycling?
Let’s take the recycling one first. It is argued that the materials that form part of the fuel mix for EfW plants could be recycled, and hence building these plants will take materials out of the recycling chain so that more raw materials are needed. This is true in theory but as is often the case, not true in practice. If everything in the waste stream could be recycled then it would be an unarguable case but that little word “if” is doing a lot of the heavy lifting in that sentence. The reality facing most waste disposal authorities is that a significant proportion of the waste stream is not suitable for recycling but still contains sufficient energy to make it viable as a fuel. For example, contaminated card like pizza boxes has virtually no value for recycling but still has a calorific value of 13.5 joules per kg so can be used as a fuel. It is similar for film plastic and waste wood so these three components of the waste stream (dirty card, film plastic and waste wood) tend not to be recycled and would otherwise end up in landfill producing methane which as we know is a much more potent greenhouse gas than CO2.
Are EfW plants clean?
The second objection is emissions. There’s no denying that EfW plants produce emissions and that is why they have big chimneys attached. However the contents of these emissions is very strictly regulated and the level of particulates produced by a modern plant is only a fraction of what it was twenty years ago. A recent study by Imperial College concluded that, “Overall particulate (PM10) exposures related to EfW emissions in Great Britain are extremely low especially when compared to annual mean background concentrations.” What the carefully phrased term “background concentration” means in layman’s terms is that other sources of combustion such as domestic wood burning stoves, barbeques and bonfires produce in aggregate far more airborne polluting particles than EfW plants but let’s be frank, go to any beach on a summer evening and you will see there isn’t a strong environmental lobby against campfires or portable barbeques.
Why not convert existing coal plants?
So, although there is clearly a need for clean EfW plants in the UK, only one or two at most get built every year and the biggest obstacle to building more is probably planning. Although the average person in the UK throws out about half a tonne of waste per year, most people would rather not think about where their half a tonne of waste actually ends up. One potential destination would be coal-fired power stations converted to run on waste instead of coal. This would kill two metaphorical birds with one handy stone; provide one more solution to the mountains of waste and reduce the amount of coal that is burnt globally.
According to the Global Coal Plant Tracker, there are an estimated 1,767 coal-fired power plants in the world and 196 in construction giving a total of 1,963 plants and an operating capacity of about 2,000 GW of capacity. And as you will recall from school, coal was formed from dead trees and plants that absorbed CO₂ from the atmosphere about 300 million years ago and a tonne of coal is 85% pure carbon. Every time you burn it, you are releasing that ancient carbon back into the atmosphere. One tonne will produce about 2.86 tonnes of CO₂ and the 1,767 existing plants repeat this simple maths everyday producing roughly 15 billion tonnes of CO₂ emissions annually, about 30% of global CO₂ emissions.
The good news is that the number of operational coal plants fell by 29 in 2019, the third year in a row of decline and 75 have shut in the last 3 years. This is creating a pool of derelict power stations which could usefully be converted to EfW plants. The practicality of this is quite straightforward; the building, power island and grid connection can all remain untouched and the majority of the work is converting the fuel handling system and the incinerator to run on Refuse Derived Fuel (RDF), a fuel produced from industrial and commercial waste. Although there is still a planning requirement regarding change of use, this is generally less contentious as the local community have lived with the plant for a long time and it is often a significant local employer.
As well as the technical practicality, the economics of conversion make for compelling reading. A brand new EFW plant will cost between £100m – £500m depending on size whereas a coal-fired plant can be converted for roughly a 1/3 of the equivalent cost. The environmental argument is also persuasive as RDF has a significant biological content of up to 45% (paper, card, food etc.), therefore has more recently captured its carbon molecules from the atmosphere in the original growing process compared to the ancient carbon locked up in coal. Using RDF as a fuel instead of coal can generate net emissions savings of up to 1.5 tonnes of CO₂ per tonne of fuel. Converting coal-fired power station into EfW plants would likely reduce carbon emissions in the power stations converted by over 50%. To use another Americanism, it’s a no-brainer.
As with their attitudes to Christians and lions, it seems pretty obvious to us that we cannot carry on like the Romans when it comes to disposing of rubbish. The amount produced per person continues to rise and the revolution in home deliveries and takeaways during the lockdown has created yet more mountains of packaging and greasy cardboard, most of which is probably being sent to landfill to rot away and produce methane. This situation clearly can’t carry on indefinitely and it is particularly ludicrous that we are burning coal whilst burying RDF. Converting power stations to run on the latter instead of the former seems like an obvious solution and we are pleased to note that other people in the industry seem to share our vision.
Uskmouth power station in South Wales will be converted from coal to RDF in the next couple of years and we expect that many other projects will follow suit. There are a lot of coal-fired power stations dotted around the world and all could be converted in time. We may be losing the cultural war against the invasion of American words, but hopefully a mere 2,000 years after the Romans went home we will finally change the way we deal with waste and turn it into electricity rather than landfill.