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Energy from Waste

At the end of their useful lives, the products and materials we use should become the nutrients and ingredients of new products and materials in a waste-free cycle mimicking those found in the rest of the natural world. That’s just common sense and uncontroversial, isn’t it? Probably most Transitioners are proponents of ‘cradle to cradle’ design and the ‘circular economy’. Those that aren’t would be, once they’ve been exposed to those ideas.

But until the transition to a circular economy is complete, there will be waste. And while we’re trying to rethink, reduce, and reuse, diverting compostables, recyclables, re-usable building materials, and reducing landfill bound rubbish to a trickle one day in the future, why not unlock as much benefit from it as possible? Relatively clean energy, for example.

If our goal is ultimately a ‘zero-waste’ society, then producing energy from waste might be a losing proposition in the long-term. In the meantime - many decades, surely - there are a range of waste streams and energy generating technologies, at a range of local and regional scales, that have important parts to play in creating local resilience, building community wealth, and reducing carbon emissions.

In Totnes, we looked at producing energy from waste while researching the Local Economic Blueprint and found enormous potential. Within the South Hams, the south Devon district that includes Totnes, the potential for anaerobic digestion using animal slurry as feedstock is about 14GWh, and another 6GWh from food waste. There’s also about 30,000 tonnes of municipal solid (MSW) and commercial waste that could be feedstock for a pyrolysis or gasification system(s), with potential for about 85GWh of usable energy. Together, that's about 10% of current energy demand in the district.

Unfortunately, waste policy at both district and county level is still trying to extract itself from the old paradigm of the ‘waste haulage’ industry, (whose name says it all, really.) Waste haulage is carbon intensive. And it’s dominated by powerful corporations who enjoy de-facto monopoly by virtue of exclusive long-term contracts which often outlast the careers of the officers and councillors who approved them. This is a significant barrier for any would-be local energy-from-waste entrepreneur.

Tresoc, the local community-owned energy company, is planning two energy-from-waste projects. One is an anaerobic digestion plant developed in partnership with Bicton College, an agricultural college which is starting a sustainable teaching farm at Dartington estate. That system would produce electricity for about 390 homes, as well as provide heating for the Abundant Life project, a planned retirement community also located at Dartington estate. It would provide 3 full time jobs and provide subsidy income through Feed in Tariff and Renewable Heat Incentive schemes, as well. All of these factors would provide direct and indirect benefits to the local economy.

While AD plants aren’t new, the other project will be breaking some new ground as they seek to deploy an innovative new design concept in pyrolysis, developed by Peter Stein. In fact, it may be the first of its kind anywhere in the country. The project would be located at a large sawmill and rely predominantly on biomass feedstock from low-grade timber harvesting and sawmill residues. It would produce about 4MWh of electricity and 8MW of heat to run a timber drying kiln on site. It will also create about 18 full time jobs and provide a nice boost to the local economy.

Both projects are small but will clearly demonstrate the importance of those energy sources toward boosting local energy and economic resilience. Will it lead to more such projects? Could it sufficiently demonstrate that pyrolysis, for example, provides a cleaner and better alternative to incineration? This is an especially important issue this summer as a major power company wants to build a large-scale incinerator in Plymouth with its toxic ash waste hauled to an open quarry in Buckfastleigh, which is on the Dart just upstream from Totnes. By the way, Transition initiative Buck the Trend, is part of a coalition engaged in fighting it and are currently raising funds for the legal fight ahead.

Generating energy from waste seems a no brainer, especially if done intelligently, at appropriate scale, and with clean technology. Hopefully, Tresoc’s projects demonstrate just that and will inspire more of the same. Time will tell - both projects are still at their earliest planning stages. Watch this space...

Images: Cradle to Cradle book, by Braungart and McDonough; LEB Totnes; a cow, producer of AD feedstock.

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Comments

Kerry Lane's picture

Wow interesting ideas. Are

Wow interesting ideas. Are either of the projects planning in actively engaging the surrounding communities about why the waste is there in the first place? In a similar vein to community owned renewables reducing energy use as people are more connected to the source, I wonder if you could reduce a communities waste AND energy consumption by engaging them in an energy from waste project?!

Katie Treherne's picture

Energy From Waste

Dear Jay,

This is a project we are getting ready to tackle also.  So it would be wonderful to share strategies.  We realize thate here in East Sussex, most of the local farmers are of retirement age.... so farm slurry may not be an option for the future.  Has anyone looked into human waste (ie the cesspool emptyings).  There are two sewage treatment plants in our village, and I am sure there are masses of regulations pertaining.  Has anyone already looked into this?  

John Webb's picture

Avoiding waste disposal

Here in Hertfordshire, we are faced with a county council that has resolved to install a mass burn incinerator for municipal, commercial and industrial waste streams. Various local groups are opposing that vigorously and to great effect (as in council elections this week!).

Eric Pickles the Secretary of State at Defra has called in the proposal and commissioned a Public Inquiry to make a recommendation to him later this year. That sort of contest is being played out across the UK, as you can read on UKWIN's web site.

In support of those efforts, and to promote sustainable local processing, we run an information hub called HertsWOW. With brilliant advice from UKWIN, we engage with councillors and officers of the County Council, with the partnership of district/borough councils, with the campaigning groups and especially with the Transition-minded community groups across the county. 

Currently we are in touch with the similar contest in Norfolk, where the group KLWIN is magnificently engaged in the Public Inquiry at Kings Lynn.

I hope that all transition groups will recognise that incineration limits the extent of recycling and that there are better, more sustainable, methods than either landfilling or incineration.

Julian Hawkins's picture

Incineration: good or bad?

There are good reasons for opposing incineration in general.  In particular, the value of materials that can be recovered, compared to the value of the energy gained from burning them.

Consider burning waste wood.  You can get around 30% to 40% of the embedded chemical energy, assuming a reasonably efficient heat engine.  But photosynthesis is generally only a few percent efficient.  So you might get back 1% of the solar energy that went into growing the wood in the first place.  (Note this isn’t meant to be an exact calculation.)

Any reasonable use for the wood’s material, even if it’s pretty crude like chipboard, is likely to be better. So we should generally oppose large scale incineration:  it involves commercial commitments that are likely to impede good recycling sometimes.

But oppose all the time?

There no good alternative use for some materials:  small amounts, or mixed or poor quality waste that take excessive energy and effort to recycle.  Or where you can extract energy and re-use the residue.  Dung is a good example:  if you convert most of the organic waste into gas, what’s left is a good fertiliser.

Also, burning appropriate fuels is “dispatchable”, which means you can control when you generate power.  One well-known (and often exaggerated by its opponents) problem of wind power is that the wind doesn’t blow all the time.  Local incineration may be a good option on low wind days in some places.

This needs a balanced assessment of the individual merits in particular cases.  So it’s worth looking at options like those proposed in Totnes.