Last week saw the launch of CAT’s new renewable heating teaching facility. The system will provide heat and hot water for several of our buildings, including the WISE education and conference centre, whilst also being used as an example system for training heating engineers and plumbers in biomass installation. Display signs will help visitors and school groups to understand the benefits, and potential drawbacks, of using biomass as a fuel.
Speaking at the launch event on Friday 7th October, CAT CEO Adrian Ramsay said: “The installation uses established and proven technology and fits well with CAT’s mission of helping people deliver practical solutions that can address the challenge of climate change.”
The system works on both wood chip and wood pellet – the first time the manufacturers have created this kind of combined fuel system outside of a laboratory. We plan to source fuel from local suppliers wherever possible, with much of the wood chip coming from a supplier based less than 1 mile from the CAT site in Pantperthog.
“A broad overview of a massive area, and a very in-depth practical outcome. Over two visits to CAT we covered everything from biogas buses to chimney design and coppicing. We carried out detailed studies of a domestic and a commercial building to design a suitable biomass heating system, calculating passive gains, heat loads based on dynamic modelling, plant room lay out and financial appraisal.
“We delivered a group presentation in the second attendance, a great opportunity to team up, learn from each other, and present our heating solution to fellow students and four tutors. I particularly enjoyed the trip to visit a local wood processing business, two biomass heating systems of very different scales with the chance to interview the owners and operators, and the IBERS centre for biofuel development. Our practicals included measuring fuel moisture content, testing and calculating the efficiency of a storm kettle, and experimenting and tinkering with various biomass boilers on the CAT site. Other factors that made it a special experience were the fantastic food, accommodation, course organisation, accessible friendly tutors, stunning location, the Tafarn Dwynant down the road, and a great bunch of students, all exploring and challenging themselves to question how we move our energy systems in the right direction.”
Biofuelwatch, a campaign organisation against large-scale bioenergy (using biomass to produce energy) have launched a new report – Biomass: the Chain of Destruction – focusing on the human and environmental costs of biomass-focused UK renewable energy policy.
The report states that:
“Large scale electricity generation from biomass is a key element of the UK Government’s renewable energy policy. Their 2012 UK Bioenergy Strategy states that bioenergy could provide between 8 and 11% of the UK’s primary energy demand in 2020 […] Although bioenergy includes biofuels for transport, the bulk of it would come from burning wood.
Biomass electricity is supported by generous subsidies and energy companies have announced plans to burn […] more than eight times the UK’s [current] total annual wood production.”
In conjunction with their report released last year – Sustainable Biomass: A Modern Myth – the organisation highlight the pitfalls of trying to meet greenhouse gas emissions reductions targets by converting to baseload biomass electricity generation plants. That is, burning large quantities of biomass (usually wood pellets) around the clock to produce electricity, similar to how we currently generate electricity from coal.
Burning biomass instead of, for example, coal, is seen as ‘carbon-neutral’ because the carbon dioxide (CO2) released in its burning has been taken in already as the wood has grown – there are no net greenhouse gas emissions over the life cycle of the biomass. Coal, in comparison, emits greenhouse gases into the atmosphere, contributing to climate change.
Most of the issues surrounding biomass use for energy derive from concerns about whether or not policies surrounding biomass growing and use will, or do work. For example, do they:
Count all the carbon in the biomass life cycle properly, and take into account the ‘carbon-payback’ time. For example, if an older, carbon-rich forest is cut down and replaced by a short-rotation (comparatively carbon-poor) stock of biomass, then the energy produced using that biomass would not be carbon-neutral in absolute terms.
Stop deforestation and the ruining of natural landscapes, communities and cultures in the process of growing biomass or establishing new plantations.
Keep biomass usage to a sustainable and non-exploitative level. Is it right to use precious land (often not in the UK) to cater for our high energy demands, when it could be used for food production or supporting biodiversity? Catering for all UK electricity demand would require tens of millions of hectares of land for growing biomass according to the report (the area of the UK is about 24 million hectares in total, as a comparison).
Encompassing all of these things, key questions are: ‘is biomass sustainable?’, and ‘is it really carbon-neutral’? And even if it is both of these things, is it actually a good option for low carbon energy provision in the UK?
The argument goes that if policy does not work, then energy from biomass is no good from many different, not just climate-related, perspectives. This means biomass use hinges on good policy mechanisms, their strong implementation, and objective and impartial verification. Are we capable of this?
It would appear that currently we are not. The new report includes the first ever study of a land-grab in Brazil for eucalyptus plantations directly linked to UK demand for wood pellets, and documents the impacts of a UK power station’s pellet demand, sourced from the destruction of ancient forests in the southern US and Canada.
Biofuelwatch member Oliver Munnion said: “This is just the tip of the iceberg, and what we’re seeing is the impacts of a rapidly growing industry and the speculative investments of irresponsible companies, spurred on by generous subsidies and non-existent sustainability standards.”
However, whilst biomass is not, and cannot be the solution to all our energy needs, it is useful in some cases, though its use should be kept to a minimum, as a ‘last-resort’. Baseload biomass (for example replacing coal with biomass in large power stations) is not sensible when biomass resources are limited, can have detrimental impacts globally, and especially when we have so many other ways of generating electricity.
Biomass in ZCB
Throughout the Zero Carbon Britain project we ask, what resources do we have for energy provision in the UK? In other words, where are our strengths? We end up with a good mix of renewables in our scenario, but we are dependent on wind (both onshore and offshore) for about half of our energy on an annual basis because we are fortunate enough to be one of the windiest countries in the world. With relatively small per-capita land area, building up our capacity to produce electricity from wind resources, rather than biomass, makes much more sense.
Furthermore, Zero Carbon Britain hourly modelling of our electricity supply and demand shows that baseload power (i.e. burning biomass instead of coal, or nuclear power) does not help cater for shortfall in electricity demand in a system that has a high degree of renewables in it. When our supply and demand for electricity go up and down at different times, what we need is a flexible back-up energy supply, not one that runs constantly – we only need to fill the gaps, not produce more energy all of the time.
And this is where careful use of biomass comes in handy. In Zero Carbon Britain, there are some energy demands that can’t currently be met with electricity (the type of energy produced by renewables) – some transport and industrial demands. Furthermore, we need to be able to store some energy over long periods of time (weeks or months). Electricity isn’t very storable on the scale necessary to cater for even the much reduced UK energy demand in our scenario. Converting biomass and hydrogen into synthetic liquid and gaseous fuels helps with these issues. In Zero Carbon Britain, we keep biomass use to a minimum. We use hydrogen produced using excess electricity (when supply from renewables exceeds demand) in chemical processes to get more out of our biomass, so that we need less of it.
But how do we ensure the biomass we require is sustainable, and actually carbon neutral? In Zero Carbon Britain:
We grow all the biomass we require for energy in the UK. In total, we use about 4 million hectares of land to produce grasses, short rotation forest and coppice. We think that providing our own biomass for energy offers us the best chance of being able to be in control of good policy implementation surrounding its growing and use, and verification schemes that keep the production sustainable and carbon neutral.
We mostly grow this biomass on ex-grazing land meaning no old forests are cut down. In fact, at the same time we plant an additional 4 million hectares of forest, providing more wood products for the UK, and leaving more space for biodiverse woodlands. There are no knock on effects for the food industry either.
Changes in diet in the Zero Carbon Britain scenario mean we can do all this, and still provide a healthy, balanced diet for the UK that needs to import less food.
The impact the UK has on land overseas in our scenario would be less than it is today.
There can be (and are currently) many serious and dangerous issues with the growing and using of biomass for energy. However, with a sensible (and limited) approach to its use, strong policy backing, and independent verification, we can make sure the biomass we use is sustainable and carbon neutral.
One of the things Biofuelwatch calls for is “a major policy shift away from large scale energy generation through combustion, towards our energy needs being satisfied through a combination of genuinely climate friendly renewable energy and a substantial reduction in both energy generation and use.” And providing that there is still some room for use of truly sustainable and carbon-neutral biomass in appropriate places, then we’d agree.
As is usual for the CAT summer building project, it all began with a 24-hour design charette in June with students working in teams or independently on their proposal for the project. The site was to be the space adjacent to the recently completed biomass building with a brief to provide a covered dry space for around 30 school children with storage for their belongings. Concurrently our designing had to hold in strong perspective that we would be the ones constructing our designs within the allocated five days, making ‘build-ability’ a key consideration. One day later, and after a heated counting of the votes cast by the students, Serenity, designed by Matt Robinson and Tom Reed, was announced as winner. Carousel followed closely in second place, a wrap-around structure of undulating frames with one frame to be fabricated by each student.
Over the following three weeks the design, materials orders, and constructional logistics for the coming week were furthered between Matt, Tom, and the supporting tutors, juggling between design intentions and constructional realities in a ping-pong rally of emails. July saw the return of the students to CAT for the build week, welcomed to the site by sunshine and dry weather. The first work on site was the labour-intensive stage of clearing the site, levelling, and setting out the slate pad foundations. We didn’t get the setting-out quite right the first time, but we learned lessons along the way.
Meanwhile, the main frames were being fabricated off-site by a separate team, with a third team dedicated to the production of the elegant timber screen that would face the most prominent elevation of the design.
Day three saw the elements rapidly come together on site, with the landscape team who had been manually slating the area called in for extra hands as the purlins, floor joists, and secondary posts were being measured, cut, and fitted. Floorboards were cut from reclaimed oak found on site and fixed to the joists with countersunk screws and plugged with wooden dowels, also used for the screen. In total, over 2,000 dowels were hand made by the team.
Day five saw the first and second section of the screen fitted to the main structure, and the first layer of timbers to the purlins. Hard as we all worked however, by the end of the fifth day there were still jobs left to do resulting in an ‘extension of time’ being granted for three further days of work in September. With reduced numbers, the returning students enthusiastically charged through the remaining tasks including fitting the final section of the screen and securing it to the biomass building with a slatted covered walkway. The construction of the horizontal slatted wrap-around to the end of the main structure dramatically changed the experience from within the space, with the final slats being fitted after dark under head-torch light.
Day eight saw the construction of the strongly-engineered bar area and following a brisk cleanup of the site, the students were able to sit down around the conversation pit and experience the space for the first time in its finished state.
Reposted from Science Omega online
As the world’s supply of fossil fuels dwindles, the search for alternative energy sources is vital. Biomass is one such energy source that is being touted as a good alternative to conventional fossil fuels. However, it is not without considerable opposition from those who argue that biomass could do more harm than good in the battle to reduce greenhouse gas emissions.
Biomass is energy created from the burning of biological materials such as plants and non-living things such as biodegradable waste. Anything that is alive or was alive a short time ago can be categorised under biomass, therefore trees, crops, animal and plant waste are all included.
The attraction of biomass in the fight against climate change is that it is carbon neutral. Unlike the fossil fuels, oil, gas and coal, which when burnt add to the net amount of carbon dioxide in the atmosphere, the CO2 that biomass produces when ignited is absorbed from the atmosphere by the crops used to make it, and so the net atmospheric amount is not increased.
“It is clear that for biomass to be part of a zero-carbon energy future, strict safeguards need to be in place to ensure that only sustainable sourcing occurs. “
Currently in the UK there are 20 dedicated biomass power plants that are producing a total of 1,092MW from a variety of sources including poultry waste and woody biomass. There are around another 30 at planning stage with a combined capacity of 5,000MW.
Given that 1MW can sustain 1,000 homes for an hour, that is a significant contribution to the UK energy mix. However like many energy sources, it is also controversial, as there are both advantages and disadvantages.
In recent years numerous organisations have issued warnings about the potential impacts of the mass production of biomass. UK-based organisation Biofuelwatch is currently protesting against plans by Drax power station in Yorkshire to convert half of their coal-fired power station to run on biomass. Whilst in practice this sounds like a green idea, “highly biodiverse forests in North America are already being clear cut to make wood pellets for UK power stations. This will only get worse as the industry expands.”
Biofuelwatch say that communities in South Africa are already losing access to land and water because biodiverse grasslands are being destroyed for monoculture tree plantations, some of which supply Drax.
Drax has the capability to produce 12.5 per cent of its output from renewable and sustainable biomass – the equivalent output of over 700 wind turbines. Drax says that ‘burning biomass at this level saves over two and a half million tonnes of CO2 each year.’
Wood has always served as a fuel source for fires and ovens, however technological advances mean that burning biomass can produce energy for everything from a power plant to an engine.
The advantages are that burning biomass is said to be carbon neutral, in that by growing and then burning it there is no creation of additional carbon monoxide. Biomass products are abundant and renewable; since they come from living sources and life is cyclical, these products potentially never run out, so long as there is something living on earth and someone is there to turn that living thing’s components and waste products into energy.
Another benefit of biomass is that we can use waste and thus reduce landfill to produce energy. However there are concerns that incinerating household waste depresses recycling and wastes resources, releases greenhouse gasses, and is often forced through against strong public opposition. Instead of promoting zero waste, incinerators rely on material for feedstock that should be recycled or composted. Incinerators create toxic emissions and hazardous ash, and therefore pose significant health risks.
It is clear that for biomass to be part of a zero-carbon energy future, strict safeguards need to be in place to ensure that only sustainable sourcing occurs. Otherwise, as the Centre for Alternative Technology’s Freya Stanley-Price points out: “We are getting rid of one environmental problem and replacing it with another.”
Friends of the Earth suggest a number of measures that include keeping the scale of biomass to the size of domestically available resources, using anaerobic digestion for the treatment of food and animal waste and focusing biomass use close to production.
In addition, there must be a joined-up, integrated approach to energy planning that considers the most efficient use of any energy generated and looks forward to managing energy demand.
“There are many things that have to be carefully considered and weighed when determining if biomass energy is a viable alternative energy source,” Stanley-Price says. “In a zero-carbon future we must make sustainable use of trees as fuel, and replant them as we harvest them – creating a continuous carbon cycle. Growing our own fuel also creates jobs and is ideal for strong, local economies.”
If you went to the National Homebuilding and Renovating Show a week ago, you might have been inspired by the live demonstrations of thatching, or felt the sudden urge to redecorate when you passed the stall full of sheepskin rugs. Or perhaps you realised you really did need a 2-metre 3D TV in your lounge, or maybe you simply wanted to browse whilst enjoying an ice cream from the Yorkshire Dales food cart (it’s a permanent installation).
Nestled between two full-size timber frame houses, one of which was the Eco Home Theatre, the CAT stall was a small hub of renewable energy debate in this varied crowd. Enthused by Tobi’s daily talks, a stream of visitors made their way to us to ask often highly specific or technical questions. Some of the same concerns kept coming up, so we’ve collated a list of the five most common questions and Tobi’s answers.
Lots of people also asked us questions about architecture and design, but we’re going to save those for a later feature. Stay tuned!
PVT is the combination of solar photovoltaic systems (the “PV”), which produce electricity, and solar thermal systems (the “T”, also known as solar water heating, SWH), which produce hot water.
In principle, you can see the potential for synergy between these technologies. PV modules convert only 10%-20% of the solar energy that falls onto them into electricity, and a good proportion of the remaining solar energy is converted into heat – solar PV get hot in the sun. So why not use this heat to heat water for showers? This is what PVT modules do – basically, they are solar PV modules put onto a solar thermal absorber. In principle, this is a brilliant idea. In practice, it’s not so easy.
Solar PV modules actually operate more efficiently when they are colder (because their electric resistance is lower) whereas for your showers you want your water to be hot. Under some conditions that works out perfectly – as long as your hot water cylinder is cold, the solar thermal part will actually cool your solar PV module down. But on a sunny summer’s day you ultimately want your solar thermal system to produce very hot water, and in fact UK legislation actually requires water to be heated to temperatures of 60-70C to kill dangerous Legionella bacteria. Ideally you’d want your solar panel to be colder than that.
You can get around this by using a heat pump to produce very hot shower water while pumping lower temperature water through your solar PVT panels. But that of course means additional expense – and much higher electricity consumption than the circulation pump of a normal solar thermal system. Also, it is worth pointing out that most PVT systems on the market today actually cost more than the combined cost of a conventional PV system and some solar thermal panels.
The Upshot: If you have enough roof space you’re probably better off installing separate solar PV and solar thermal systems.
2. Is there a case for thermodynamic systems? So-called “thermodynamic” systems (a fancy term that doesn’t really mean much) are essentially simple (unglazed) solar thermal panels connected to a heat pump. They haven’t been on the market for long enough for us to have good data, but there’s reason to be very sceptical. In the UK there simply isn’t much solar energy available in winter because days are short and the sun is low down and very often hidden behind clouds altogether.
Under those conditions, a “thermodynamic” system is essentially an air-source heat pump (ASHP) that relies on heat transfer from the ambient air to the solar panel. Manufacturers claim that the system will provide hot water at every time of the year – and that is probably true, but during dark winter days this energy is not solar energy but rather energy produced by a heat pump, which consumes a lot of electricity.
Furthermore, because the “thermodynamic” panels usually use a type of solar panel that’s less efficient than a normal (glazed) solar thermal panel, they’re probably also not a good choice during the sunnier parts of the year when a normal solar thermal system can produce hot water at a much lower electricity cost.
The Upshot: A large dose of scepticism is currently warranted when it comes to these systems. This is also reflected by the fact that their accreditation under the Microgeneration Certification Scheme (MCS) has been suspended, which means you won’t get Renewable Heat Incentive (RHI) income.
3. Are heat pumps right for me? The answer is “it depends”. Heat pumps use electricity to extract ambient heat (heat in the air or ground) and supply that heat into your house. Today most electricity is produced very inefficiently – for instance, our coal and gas power stations consume two or three units of fossil fuel heat energy for every unit of electricity they produce. If electricity from these inefficient power stations is used to run heat pumps, then these heat pumps need to be very efficient. Basically, your heat pump would need to supply three units of heat for every unit of electricity it consumed, otherwise you might be better off heating directly with oil or gas!
To work efficiently, heat pumps need to run at a relatively constant rate supplying heat at low temperatures. This is a realistic option for a (usually new-built) house that is well insulated and has underfloor heating with densely spaced pipes. In this case even when it is very cold outside the water in the heating system need only be lukewarm (maybe 30-35C). On the other hand, if the heat pump needs to supply much hotter water, for a badly insulated building or a building heated by radiators, then the efficiency of the heat pump will likely be too low to make it a good choice.
4. Micro hydro: yes or no? Hydropower is great, and if it benefits a whole community rather than one individual then all the better! Unfortunately, only a minority of communities in the UK have the kind of site that’s suitable for hydropower: A stream with a large flow rate of water and a good height drop. If you have a site of this type then it’s definitely worth exploring the option of installing a micro-hydro scheme.
5. Should I heat my house with biomass? Biomass can be a good choice, especially where wood can be sourced locally and/or for buildings where heat pumps would not work at high efficiency. But it’s important to stress that wood fuel is a limited resource and that there are potentially negative side effects to burning it (e.g. local air pollution from smoke, time lag between when CO2 is emitted and when a new growing tree absorbs it again). This doesn’t mean we shouldn’t burn wood, but it means we should try to use it as efficiently as possible. This means always reducing a building’s energy consumption first, and using the most efficient appliances available for burning wood. For example, modern log batch boilers (wood gasification boilers) get more heat out of the same amount of wood, and emit less smoke, than traditional wood stoves (or, even worse, open fires!).
CAT’s new HETAS accredited Biomass facility is used for our Installers Short Course as well as allowing our postgraduate students to learn about the possibilities of biofuel heating. Check here for more information about Biomass.
Postgraduate study at CAT includes REBE and AEES courses, both of which teach students about sustainable heating.
The new short courses at CAT also include Building Regulations for Biomass Installers. This course is intended for heating engineers wishing to attend the Biomass for Installers course but have not undertaken the HETAS H003 and H004 courses.
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.
• 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.
• 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.
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.