Be a CAT Volunteer for a Week in May


Do you fancy spending a week at our beautiful site, and being part of a team doing practical work to help CAT prepare for the main summer season?


We’re holding a short-term volunteer week from 27-31 May, and we’d like to invite you to take part. The exact range of tasks on offer will depend on a number of factors, including the weather, but is likely to include work in the gardens, with our buildings and maintenance team, and with our water and natural resources team.


It’s a great chance to enjoy staying on-site at CAT at a lovely time of the year, to get “behind the scenes”, interact with staff and other volunteers, and maybe learn a few new skills. If you fancy taking part, please contact Sally Carr (, 01654 704976).


We have different accommodation options available depending on your budget and preferences:


En-suite rooms in our beautiful new facility, the Wales Institute for Sustainable Education (WISE), fully catered – £200 per person

Rooms with shared bathroom facilities (not WISE), fully catered – £150 per person

Self-catering accommodation (with lunches provided) – £70 per person


Volunteers in the garden
Volunteers working in a polytunnel at CAT


An Introduction to Biomass

After a brief sidestep into the realm of policy with last week’s Green Deal post, we turn our focus back to renewable technology. This week we are looking at biomass.


Biomass is biological matter composed of living, or recently living organisms, which can be burned or broken down by anaerobic digestion to produce energy. Examples of biomass include wood, straw, animal waste, agricultural by-products and energy crops like oilseed rape. Domestic biomass boilers usually burn logs or wood pellets, so this post will be focusing mainly on wood biomass.

Historically, heating homes with wood was the norm. Today, the practice is popular in mainland Europe and the USA. Many houses in the UK have a fireplace, although heating an entire house using biomass is less common. With the introduction of the Renewable Heat Incentive (see the policy section below) the popularity of biomass as a potentially cheap and sustainable way of heating the home is expected to increase.

So how sustainable is biomass? Burning wood or straw releases carbon stored in the plant matter over the course of its lifetime. When fossil fuels are burned, they release carbon absorbed over millions of years. The carbon released by burning biomass is converted into new plant material by photosynthesis, negating the release of the stored carbon. However, it is important to note that wood biomass is only sustainable if the forests it comes from are properly managed. There is a limit on the land area available to grow these fuels, meaning that in the future biomass will be one of several renewable energy sources used to heat our homes.


The Upside

• Biomass is much more environmentally friendly than using coal, oil or gas. Heating the average home using a wood pellet boiler rather than oil would release 10 times less carbon dioxide (CO2) every year.

• Burning logs or wood pellets is generally cheaper than using oil or electricity. If you can harvest your own wood then it will be even more cost efficient. The Energy Saving Trust estimates that replacing an electric heating system with a biomass one can save roughly £630 per year, with a CO2 saving of 7.5 tonnes per year.

• Biomass energy sources are renewable, but we must make sure that they are sustainably managed.

• There are several different types of biomass, so you can choose which one best suits your situation.

• It is possible to use biomass from local sources. This minimises carbon emissions from transportation, and also supports the local economy. Search for local wood fuel suppliers using Log Pile.

• It is easy to store wood pellets in your home, even if you live in a small house. To see an example of a wood pellet stove being used to heat a home, watch this video.

CAT's wood pellet boiler with automated feeder. To the right are our two log boilers.

The Downside

• Installing a biomass system can mean high initial costs. A simple log stove can cost around £500, with an automated wood pellet boiler costing up to £15,000.

• Biomass is a low-carbon technology, but it is not carbon neutral. The harvesting, processing and transportation of materials all contributes to CO2 emissions. Wood pellets require more processing than logs, but they have a lower moisture content so they burn more efficiently.

• It is cheaper to order fuel in bulk, but storing large amounts of  logs can be difficult in smaller homes.


The 2008 Climate Change Act is a legally binding agreement that the UK will reduce its net carbon emissions by 80% by 2050, compared to emissions in 1990. Government policies like the Green Deal and the Energy Company Obligation are all aimed at reducing the UK’s carbon output and encouraging people to embrace less carbon-positive fuel sources.

The Government’s latest scheme is the Renewable Heat Incentive. This will operate on a system similar to the Feed-in Tariffs for wind and solar energy, with householders who take up the scheme being paid for heating their homes using renewable energy. The domestic RHI has yet to be launched in the UK, although the non-domestic scheme has been in place since November 2011. The domestic RHI is expected to be launched this summer. More information can be found on the Government website.

Preceding the launch of the RHI is the RHIPP scheme (Renewable Heat Incentive Premium Payments), giving householders money towards upgrading their heating systems.

A look inside one of CAT's log burners

And did you know…

Over the past year CAT has been building a biomass teaching facility, which has just opened. Approved by HETAS – the regulatory body for biomass installers – CAT now offers Biomass for Installers (HETAS H005). Intended for experienced plumbers and engineers who want to expand into the renewable heating market, Biomass for Installers will enable those in the plumbing and heating sector to move in to the renewable energy field.

In Ofgem’s last quarterly report of 2012 it was noted that 90% of installations done as part of the non-domestic RHI were for biomass boilers. With the imminent roll-out of the domestic RHI, the number of skilled biomass installers required can only increase.


More information on biomass can be found on CAT’s info page.

Let the wood lead you: making gates from materials harvested in CAT’s woodland


Adam Thorogood, our woodland management officer, manages CAT’s woodland at the CAT site and at Coed Gwern nearby. In this blog, he explains the intricacies of making gates from chestnut.

The mallet, heavy in hand, smacks down onto the back of the froe and a reassuring cracking sound follows as the chestnut log I’m splitting cleaves lengthways. Nothing else sounds like it, a tinkling, crinkling sound as the wood fibres spring apart, relieving long-held tensions. A few movements with the froe handle and the two sides of the log ping apart. I’m making a gate. These two pieces will be the head posts, I’ll shape them with the side axe then smooth things off with the draw knife and spokeshave and move on to the next component.

The wood tears slightly around a knot and I turn the piece around, come at it from the other direction, smoothing the knot down so it becomes a feature rather than an obstacle. I’m absorbed in the work, slowly all the components emerge from a stack of round wood logs. The shavings peal away from the wood, yielding to the blade of the draw knife, tumbling onto the floor, adding to the great pile that is amassing there.

The auger bit bites deep into the chestnut, this is where the elbow grease comes in. It takes concentration and patience to guide the bit in, keeping the brace steady and at the right angle whilst turning at the same time. Despite the many times I’ve done this, I always approach this part of the process with trepidation, it needs and clear head, not to be done with too many thoughts flying around. It’s in this way that the material influences the craftsman, shapes them as they shape it. If anything, working with wood has taught me patience, that oft touted virtue, its something inherent in wood, embodied in it almost, in the long years it has taken this tree to grow, on the same spot, watching the seasons come and go. Approach the wood with a confused mind or a head full of frustration and you’ll double it, let the wood lead you and you’ll end up with something beautiful…hopefully.

This chestnut is from the woods on site here at CAT. Planted forty or so years ago, it’s seen a lot of seasons and been witness to the CAT emerge from the abandoned slate quarry that it was before into a thriving education and demonstration centre. The decision to fell the tree wasn’t made lightly, but is part of a long thought out management plan based on the principles of sustainable woodland management. The stump or “stool” that is left will throw up new shoots this spring as sweet chestnut coppices well, and when several years more have passed, we’ll have more raw material for products.

This gentle interaction between the woodland and the woodsman, between wood and craftsman, is something to be cherished. The natural environment is our life support system and through understanding it we can step closer to making our communities more sustainable. CAT is a place where such an interaction has been nurtured over the years, as the old slate quarry has flourished at the hands of its inhabitants.

If you’re interested in learning about sustainable woodland management or greenwood crafts, why not take part in one of our short courses taught by master woodsmen? Or, if you live locally to CAT, get involved in our woodland management work by volunteering on our ‘woody Wednesdays.’


Interested in learning about sustainable woodland management?


At CAT, our biology and natural resources team manage 20 acres of woodland – at the CAT site and at Coed Gwern, nearby. We also run a range of courses designed to teach you the skills you need to sustainably manage a woodland, or to develop traditional skills such as willow weaving and blacksmithing.

This video gives a taste of what it’s like to learn skills in woodland management at CAT. Book now for our first course in sustainable woodland management of the year, beginning on the 25th of February.



Here’s what’s on offer in CAT’s woodland in 2013:

Greenwood crafts

Willow Basket Making

Charcoal and Biochar

Introduction to Rustic Chairs

Sustainable Woodland Management

Introduction to Horse Logging

Tools for Greenwood Crafts

Willow Sculptures

Traditional Blacksmith Skills

Coracle Making

Hedgerow Herbalism

Earth Ovens


Photo: in the woods


This week we’ve had the assistance of some wonderful volunteers in our woodland, Coed Gwern.

CAT currently manages twenty acres of woodland spread across the main site and at Coed Gwern, an idyllic sustainably-managed deciduous woodland. The woodlands are a range of different ages and include coppice, mature broadleaf and conifer, with a mosaic of diverse microclimates and ecosystems.

Rob, our natural resources co-ordinator, says

The volunteers are fundamental to the success of our work and help preserve and enhance the extraordinary range of biodiversity that is part of west Wales’ unique ecosystem.

Thanks to the volunteers for their help!

Fantastic opportunity for volunteers at CAT’s Woodland and Biodiversity week


The Centre for Alternative Technology is offering the chance for five volunteers to spend a week assisting our Woodland and Biodiversity team. Taking place from the 5th – 9th November, participants have the option to stay on site within beautiful surroundings near Machynlleth at the heart of Wales.

The Centre for Alternative Technology (CAT) has a strong commitment to the preservation of the environment and enhancing biodiversity. CAT currently manages twenty acres of woodland spread across the main site and at Coed Gwern, an idyllic sustainably-managed deciduous woodland. The woodlands are a range of different ages and include coppice, mature broadleaf and conifer, with a mosaic of diverse microclimates and ecosystems.

November’s Woodland and Biodiversity week will be overseen by Rob Goodsell and Adam Thorogood, CAT’s biology team. Volunteers will be working with Rob and Adam to practice woodland management skills across the site, including thinning, invasive species control and formative pruning. Participants will learn the safe use and maintenance of hand tools. There will also be the opportunity to survey and maintain CAT’s bird monitoring programme.

“The volunteers are fundamental to the success of our work and help preserve and enhance the extraordinary range of biodiversity that is part of west Wales’ unique ecosystem” – Rob Goodsell, Natural Resources Co-Ordinator

For £120 the week includes full-board accommodation in a shared bunkhouse. This one-off opportunity is limited to five spaces, so booking early is recommended. As the work may be physically demanding and will require working in all weather conditions volunteers are advised to bring waterproofs and boots.

The week will be free to attend if you do not require accommodation. Lunch will be provided.

If you would like to join us for this fantastic opportunity then contact us by telephone on 01654 705955 or by email at If you would like to learn more about our commitment to woodland management then please visit CAT’s website.

Photo: the wood store


This incredible image of the wood store at CAT was taken by artist Tanya Stiles on a recent visit to CAT.

I have worked as a commercial designer for print and digital media for many years, now I have the time to really enjoy and develop my first love, art. Most of my pictures are slightly abstract and often based on nature. Themes or pictures usually start with a walk in the countryside or city.

Favourite materials for sketches are lovely messy paint, inks, pencils and pastels, and I also take many photos. These sketches and photos help me to work through ideas before creating digital images – on my powerful and highly capable computer. I use a very large monitor with great depth of detail and tonal range, a digital pen and top quality software. This working stage takes many hours to achieve the desired results.

You can contact Tanya at Do you have any images of CAT you’d like to share? Email them through to us at

Where’s the impact of a book?


Last time, we had a look at the impact of a cotton t-shirt. We found that cotton production relied on the use of dangerous pesticides, that dye use polluted waterways, and that sweatshop labour still pervades the clothing industry.

This week, we’ll have a look at the impact of a paperback book. We produce an incredible amount of books on a annual basis – figures for the US from 2006 put it at a cool 4.15 billion, a fairly significant amount of which (potentially around 40%) were never sold. And while, as we’ll see, the processes involved in producing books take a considerable carbon toll, reading is a pretty carbon-unintensive recreational activity (unlike, say, international travel or water skiing).

We could even push the boat out further and say that is has a beneficial effect on our relationship with the environment, as books have played a large part in raising awareness about climate change and environmental damage. As a non-instamatic activity and one that engages our imaginations, extending our ability to be empathetic, they can “halt the consumerist lifestyle in its tracks,” according to Mike Berners-Lee.

The average book has a fairly long life. First, there’s the painstaking process of composition, then editing and design. Trees are felled, debarked, pulped and shipped to a printer, where the final product is brought to life. Then it’s back to the publisher, eventually to be distributed to retail outlets across the country. In this quick assessment, we’ve chosen to focus on forestry, paper production and ink production.

First, let’s have a look at where the paper comes from. Most books are produced using virgin, rather than recycled, fibre. It’s this emphasis on forestry which contributes to the book industry’s significant carbon footprint – forestry is responsible for 62.7% of the US’s 12.4 million metric ton carbon footprint.

Deforestation is an extremely environmentally detrimental activity. The world’s forests store a significant amount of carbon, as does the soil they live in; in cutting them down, we lose a great deal of this carbon back into the atmosphere and reduce the amount of trees turning carbon dioxide into oxygen through photosynthesis.

Disturbingly, fibre is still sourced from endangered forests all over the world. The UK’s paper primarily comes from Scandinavia, where, as Friends of the Earth report, “the majority of the natural boreal forest has been converted into an intensively managed secondary forest of plantations, where the inhabitants of a true and complex eco-system struggle to survive.” Only 5% of the old-growth forest remains, and yet it’s still being logged.

The loss of forests also has a devastating effect on indigenous and local communities whose cultural identity is closely interwoven with the forest environment.

More publishing companies are moving towards using recycled fibre, though their efforts are in part hampered by the higher price of recycled paper. Although it’s easy to recycle, around half of the amount of paper we annually consume ends up in landfill, a symptom of unfavourable logistics: most most paper production plants are in rural areas near forests, while most paper is discarded in highly urban areas.

The process which transforms trees into pages is also environmentally detrimental. An extremely energy intensive process, paper production also uses a large amount of water as well as toxic chemicals.

Particular concerns have been raised about the use of chlorine to bleach paper to make it that brilliant white – it’s been shown to cause respiratory diseases, cancer, damage reproductive systems and affect development. Organchlorides, produced as byproducts, are also hazardous.

The toxicity of the industry is highlighted in these figures from the US: paper and pulp manufacturers are the fourth largest industrial emitters of greenhouse gases, releasing 212 million tons of hazardous substances into the air and water on an annual basis.

All of the above would be largely pointless without the somewhat magical properties of inks. Comprised of varnish, solvent, colourant and additives, ink production also utlises dangerous materials.

While the use of heavy metals in the printing industry has decreased significantly, many are still use. Titanium oxide and iron are used as pigments; cobalt is used as a drier; aluminium and brass are used for metallic inks. Heavy metals can leech into groundwater and can be inhaled by workers, leading to neurological damage, birth defects, and reduced fertility.

What else could we add to write the story? Leave us your comments below!

What are the impacts of the things we buy? Where is the energy used? What are the impacts on other people and the environment?

Where’s the Impact? is an innovative teaching resource exploring the ecological footprint of products. There are literally thousands of processes involved in the production of any given product – to raise awareness about the impacts of production, pupils use a set of cards to tell the story of a product from beginning to end.

A special offer on the game is available until the 31st of March. £21 for 1-4 copies, £19 for over 5, £17 for over 10 and £15 for over 20. Buy Where’s the Impact from the CAT Eco Store 01654 705 959 or email