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Tag: hydroelectricity

  • HPH182 : Extracting energy from watercourses by generating electricity and extracting heat – with Justin Broadbent from ISO Energy

    HPH182 : Extracting energy from watercourses by generating electricity and extracting heat – with Justin Broadbent from ISO Energy

    Justin Broadbent from ISO Energy explains the options available for extracting energy from water on your plot of land.

    Interview with Justin Broadbent

    It’s our second chat with Justin Broadbent who is the chairman and founder of ISO Energy, a renewable energy installer. Last time he explained what a ground source heat pump is.

    Water gives more energy than wind because of its density

    There is a long history of using watercourses to drive mechanical objects in the UK. Although grain grinding was wind-powered, the mills of the early Industrial Revolution were driven by water because of the amount of power in it.

    Extracting heat from water can be simple and efficient

    If you have a small stream running through your garden, the simplest and most worthwhile thing you can do is extract energy in the form of heat. Justin says, “If you have the right spot and you have the right watercourse, then it is fantastic.”

    Any water can be used for energy extraction

    A large pond can be used for extracting heat; the amount of energy depends on the size of the pond and the heat load required. A flowing river has a constant temperature of 7 to 12 degrees, and a pond can get much warmer.

    If there’s a flow in and out of the pond, the energy is effectively being replaced all the time. With a stream, the energy is quickly replaced so more heat can be extracted.

    Choose the correct heat extraction device

    In a pond with fairly slow running water, Justin would install a simple mechanism that extracts heat using coils of plastic pipe.

    Lake ‘Loop Collector’

    In slightly flowing water he would use ‘Energy Blades’. These banks of stainless steel ‘radiators’ extract an enormous amount of energy. Justin explains, “Almost whatever you take out, as long as you don’t actually freeze the water, two seconds later, there’s new fresh water coming down the stream.” Such systems can be scaled up to extract hundreds of thousands of kilowatt-hours a year, by putting in banks of multiple radiators.

    Installing Energy Blades
    Energy Blades in action

    You may need planning permission

    In an area of outstanding natural beauty you must obtain planning permission for works like these. Additionally, Justin says you would need permission from the Environment Agency to dam a river or stream, but not if you wanted to put an Energy Blade in the water as it’s easily removable.

    Expertise is necessary but installation is relatively straightforward

    Justin says that extracting heat from water is cheaper and more efficient than from the ground, which is not as straightforward. He says it’s worth employing professionals but essentially, if you’re fortunate enough to have a stream, you can easily install an Energy Blade for two to three thousand pounds. To do the same in the ground, he estimates a cost of five or six thousand pounds.

    Heat extraction doesn’t have to be hugely invasive

    Some of Justin’s clients make a feature of how they’re heating their house, for example diverting part of their stream, and adding a canal and viewing walkway. But you can simply put the energy blade in the stream and dig a small trench back to your heat pump.

    Hydroelectric generation ideally needs both volume and flow of water

    To generate electricity from water, you need the water to drop enough between the top and bottom of the stream. The greater this ‘flow’ or ‘head’, the more power you can generate. Justin summarises, “In an ideal world you have head and volume and then you can build a traditional turbine. If you don’t have the head, then you have to have even more volume.”

    Traditional hydro systems are built near big mountain rivers in places like the Alps, Scotland and Wales. The right features are not easily found in the south of England and where they do exist you’d be unlikely to get planning permission.

    If you can’t have a turbine, look for old water mills

    In Southern England, generating electricity from water is rare. However, Justin’s company has converted several mills where turbines can’t be used but the volume in the hill stream is sufficient to drive an ‘Archimedes Screw’, where the flow of water turns an electrical generator.

    Archimedes Screw in action

    The same feed-in tariff for photovoltaic cells applies to an Archimedes Screw

    Some of these systems generate a constant 15 to 20 kilowatts of electricity an hour. As this is far more than a single house needs, you can sell the surplus back to the electricity companies. Justin adds, “If you have photovoltaic panels on your roof, they might produce a few kilowatts. Well, an Archimedes Screw should be able to generate tens of kilowatts. Much more efficient.”

    These are low maintenance, robust systems

    Energy blades are fairly static and require very little maintenance. As they are stainless steel they don’t rust and have quite a long lifecycle. Furthermore, they are protected by guards built on the front.

    Likewise, Archimedes screw systems are heavy but fairly basic, just needing the bearings replaced when they eventually go and some maintenance of the gearbox.

    Environmental considerations can add costs

    Heat extraction in streams won’t affect wildlife, as the amount of energy taken out is so small in relation to the volumes involved. A pond cooling may affect wildlife slightly, but Justin is reassured that those species survive lower temperatures in Scotland.

    Justin explains that you can’t block a stream completely to use the power of the water. One common, though costly, method to ensure that fish, eels and animals can get by is to use a ‘fish pass’. A maze of gradual drops allows fish to swim upstream, avoiding the mechanism.

    You get less return on investment with a smaller system

    There’s not much difference in the cost of a small system producing five kilowatts and one giving 10 to 20 kilowatts of energy, because of the costs of getting permissions, civil engineering and manufacturing. Justin explains that his company rarely works on systems that are producing less than 20 kilowatts. “Suddenly you’ve found that it’s all going to cost £150,000 and you’re only going to make £5,000 a year out of it. It doesn’t pay back.”

    ItemApproximate Cost
    5 kilowatt Archimedes Screw £15,000
    20 kilowatt Archimedes Screw£60,000
    Civil engineering£20,000
    Fish pass£30,000
    Planning permission / consultant’s time£40,000

    It’s worth investigating how to use any water source on your plot

    You may be able to generate electricity or heat, or even both, from water on your land.

    With current government incentives (those for generating electricity normally last 20 years, and about seven years for heat), Justin calculates you can get your money back on a heat system within three to five years, followed by hugely reduced running costs.

    And you might even be able to get government incentives to support the construction of the system. “So, it’s definitely worth doing,” Justin says, “So long as the government grants are out there.”

     

    Find out more

    Visit the website of ISO Energy

    Follow ISO Energy on Twitter

     

    Transcript

    Download a transcript of the interview with Justin Broadbent

     

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  • HPH126 : When is it right to demolish and rebuild? – with Simon Sturgis from Sturgis Carbon Profiling

    HPH126 : When is it right to demolish and rebuild? – with Simon Sturgis from Sturgis Carbon Profiling

    Architect Simon Sturgis explains the circumstances around whether it’s best to retrofit or rebuild.

     

    Interview with Simon Sturgis

    For the last 8 or 9 years, Simon Sturgis has been looking at the issue of carbon in construction. This followed a period of doing a lot of retrofit work where it seemed that huge amounts of only partly used materials were wastefully being thrown away. They decided their challenge was to be whether this could be quantified, which developed into the idea of carbon valuing: a valuation using carbon as a currency of sustainability.

     

    “To make anything takes up energy, and depending on where it’s made, it determines the sort of energy”

    People were already familiar with measuring energy usage in buildings, but Simon explains they were keen to come up with something equally familiar that related to materials, and the problems around the negative aspects of how they’re made.

    Where the material is made will determine the kind of energy that is used to make it. For example in Norway it would probably have been made using hydroelectric energy, however in the UK it would more likely have been using gas and oil.

    “So it’s really understanding that and trying to redirect our ability to make things away from, if you like, damaging carbon intensive technologies.”

     

    Ensure any new building has the ability to be recycled and re-used

    Simon discusses what you should consider if you’re thinking about demolishing a run-down old building to replace it with something new. He says that if it’s falling apart then it’s probably better to take it down and dispose of and recycle it as best you can, but build something in its place that fulfills the durability factor that the previous building didn’t have.

    In your new building, consider whether it is capable of easy recycling or adaptability and re-use. If you’re constructing it from brick then you might be confident it will last a couple of hundred years, but if you’re using timber you might say that it’s not going to last as long but at least it can be adapted, re-used or moved to do other sorts of things with it.

     

    A change of mind-set is needed

    People need to change their way of thinking to a ‘circular economy’. Simon explains that in the City of London office buildings have an average life expectancy of around 17 or 18 years, which clearly is going to have a huge carbon investment. He believes that there should be planning at the outset for a building’s eventual disposal, and with the expectation that when you’ve finished with the building it can be taken apart and the elements distributed to be re-used in other buildings, not necessarily in the same place.

    If you intend to re-use things you need to consider right at the beginning how they will be put together, in order to make it possible to dismantle and re-use them, i.e. using a lime mortar that can easily be removed from bricks, instead of cement mortar.

    Simon uses the example of a two-storey office/shed type building where, because of its steel bolt and aluminium construction, they were able to help a client to take it apart, move it to a more suitable location, and re-build it, while tidying it up as they went along. They were able to re-use around 70% of the materials and along with significant carbon benefits, it cost 25%-30% less than a new building of the same size.

     

    The cost of recycled products can be prohibitive

    This may seem counterintuitive at a glance, but it’s cheaper to buy new bricks than old ones. Largely this comes down to the cost of cleaning up the bricks from a dismantled building is high.

    However Simon suggests that if the process of cleaning the bricks was paid for through social value, for example being done by people who might otherwise be in prison, then not only could the recycled brick be bought for the same price as a new one, but you’re also contributing to social issues and turning the demolition process into a positive one.

     

    You can’t necessarily demolish any building

    If thinking about demolition, consider the following:

    • Whether it has listed building consent or is in a conservation area.
    • Possible health and safety issues if the building you’re demolishing is next to a sensitive site or railway line, etc.
    • Whether there are issues to be resolved due to party walls.

     

    A high standard of retrofit may have the lowest carbon impact

    Sturgis Carbon Profiling produced an article looking at carbon emissions over a period of time in 3 different scenarios.

    The first scenario was the carbon cost of maintaining an existing Victorian terraced house – principally in heating and energy use.

    The second scenario looked at taking that same Victorian terraced house and upgrading it to a high standard. While that does take a lot of material going into the building, it does make a huge difference to the performance and requirement for heating.

    The third scenario looked at building an entirely new Passivhaus, with its high levels of insulation and airtightness.

    Their analysis considered both the carbon emissions from the materials used, together with carbon emissions from day-to-day use. What they found was that, based over a 60 year period, it was better to retrofit the existing terraced house to a high standard than it was to build the new terraced house. The reason for this is because there is so much energy used in producing bricks and other materials for the new build.

    “So it’s not necessarily the case to say you should demolish Victorian buildings if you want to get a highly efficient carbon outcome. You need to make them work better… And in a sense we’re doing society a good service by re-using things rather than flattening them.”

     

    Transcript

    Download a transcript of the interview with Simon Sturgis.

     

    Find out more

    Visit the website of Sturgis Carbon Profiling

    Follow Sturgis Carbon Profiling on Twitter

     

    The Hub update

    The Hub is an extra learning and networking resource, tying together everything we’ve learnt from our podcasts, together with extra information and interviews. We have video case studies and currently have a number of short videos showing the different stages of the Long Barrow Passivhaus project that we’ve been following. We’ll also soon be confirming details of our second case study.

    Each month we’re also adding a new module which lays out different parts of the self-build process in simple steps.

    Our current beta launch price of £45-a-year, which is a lock-in price that you will keep every time you renew, is going to expire at 9pm GMT on 30th April 2016. After that the price will go up to £99-a-year. Find out more.

     

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