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There is power in a union rep

16 December 2009

Green rep Wayne Walters explains how a groundbreaking project to recycle food waste into energy could help pave the way for a greener civil service.

Not so long ago when meal times at the prison where I work had finished, we would throw all the scraps that the prisoners and staff left behind, and all the metal food tins, into a big skip ready to take to landfill.

The cost of hiring this skip alone was about £1,500 a month. So it was costing the prison management, and therefore the taxpayer, £18,000 a year just to clear our plates. That is before you even think about the cost to the environment of all those skiploads of waste.

And if that was happening at Guys Marsh, it must also be happening in prisons across the UK, and at other big workplaces. It all adds up.

Wayne Walters

Green rep Wayne Walters hopes other prisons will start recycling their food waste into electricity (Photo: Andrew Aitchison)

Well, not any more because we are recycling our food waste into electricity. This energy powers the machine that turns more waste into electricity, which powers the plant...and so it goes on. Very soon, the system will be 100% self-sufficient.

As far as I am aware this is the only such system, known as an anaerobic digestion plant, in the Prison Service and possibly even the civil service.

It works by turning the food waste into methane gas which is then used to run a generator. Solid waste from the process is also used around the prison as a fertiliser.

We collect food and garden waste, anything that will biodegrade, from around the prison and put into a tank and heat it for between three and 21 days.

When you consider that the prison’s 570 prisoners get through a total of 1,700 meals a day, you can imagine that there’s a lot that we used to throw away.

A greener future

This has been a major boost for the prison, but also a great opportunity for me and the prisoners. I have worked at Guys Marsh as an instructional officer since 2004.

I used to work in the prison workshops, most recently helping prisoners to make light switches and fittings. When this project came to an end, I was asked to set up the digestion plant.

I employ eight prisoners at the moment, who help me to collect waste and run the plant, and this will be increasing to 12 in the near future.

It’s a great thing for the prisoners to be involved with, and we are leading the way in showing prisoners what we can do with waste material and how we can use this as energy.

It was a huge task to set up the system and I have been working closely with the prison management.

I’m currently attending a course about the environment through PCS and I am looking to expand on this at a later date. I've also become the PCS green rep at Guys Marsh – this is something I’m enjoying and finding a challenge at the same time.

As well as recycling waste into energy, we also recycle the metal cans the food comes in and collect rainwater from the roof. We have also started to recycle all the furniture from around the prison and a lot of the prisoner clothes are being recycled.

I would really like to see other prisons start to recycle a lot more of their waste. This is something that most could do that would not only save running costs but would also go a long way to saving our planet for the future.

As our prison governor Julia Killick said: “Prisons are usually thought of as bad places to be, but there is a lot that is positive going on at Guys Marsh.”

Recycle and reuse

Turning our food waste into electricity is not the only way we are trying to make a difference to the environment. There are a range of things we are doing, which all contribute:

  • The tins that come of the food comes in are broken down and sent to a local company for recycling
  • The waste by-product left from the digestion process is used as compost on the prison gardens
  • We are growing own vegetables in greenhouses and have a wildlife conservation area on the site
  • We are installing a new boiler that will burn wood chips instead of diesel
  • We want to offer qualifications in recycling for prisoners
  • Our site manager has plans for a disused house on the grounds to be turned into an eco-centre open to the public as well as an education facility for prisoners
  • We are recycling furniture from the prison where previously we would have thrown it away
  • We hold wing-based competitions around energy and water use with prizes for those who reuse and recycle.

Waste into power: how it works

Anaerobic digestion is the natural breakdown of organic materials into gas and solid fertiliser.

The organic waste is sealed in a tank and heated to around 67 degrees Fahrenheit for several days where it is broken down by bacteria.

The solid by-product is relatively odourless and can be safely spread onto farmland or composted, which breaks it down more effectively. The composted material is an excellent natural fertiliser and growing medium.

Liquid is drained and pumped into a fermenting tank where it produces biogas – a mixture of methane (around 70%) and carbon dioxide (30%).

The methane can be burned to produce heat – which in a fully operational unit, can be used to help keep it at the correct temperature, or heat buildings – and electricity, which can provide power elsewhere on the site or, in larger systems, exported.

Biogas does not contribute to increasing atmospheric carbon dioxide levels because the gas is not released directly into the atmosphere and the carbon dioxide that is produced comes from an organic source with a short carbon cycle.

After removing carbon dioxide and other trace gases, the remaining methane is known as renewable natural gas or biomethane.

Biomethane is virtually identical to natural gas, with the main difference being that it is produced in days, rather than taking millions of years.

The uses for biomethane are as varied as those for natural gas, and can include heating, cooling, as a source of chemicals, fertiliser or hydrogen.

When used as a vehicle fuel, biomethane is the world’s cleanest and most environmentally friendly fuel.

Sources: Bioplex Technologies and Organic Power
 

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