According to the UK Department of Energy and Climate Change in October 2012 in their estimates of home insulation levels, there are 26.9 million homes in the UK.  They conclude that 66% of homes with lofts have loft insulation of 125mm or more, 69% of homes with cavity walls have cavity wall insulation, and just 2% of homes with solid walls have solid wall insulation.  These figures have been improving, with 320,000 more homes having installed loft insulation and 150,000 having installed cavity wall insulation between July and October last year [1].  Despite this there is clearly room for more homes to improve insulation, and with recycling and reuse at the forefront of green thinking, recycled insulation products should not be ignored.

Why is home insulation important?

The benefits of effective home insulation are simple.  The less heat that is lost when it is cold outside and the less heat that is absorbed when it is warm outside, will mean less energy will be required by heating and cooling systems and therefore energy bills will be less, thus saving money and reducing the carbon footprint. The importance of insulation becomes apparent when you take into account that somewhere in the region of 50% to 70% of the energy used in a household is used for either heating or cooling [2].

Alternative materials and their advantages

Many common insulation products are already produced using recycled materials.  For example loft and cavity insulation can often be found to be made of recycled news paper.  The market for recycled insulation has been on the up for the past decade, and many manufacturers now offer a range of products that not only better man made synthetics in terms of green credentials but also in terms of performance.  The following list provides an overview of some of the natural materials available to be used as home insulation and their respective advantages. All have the advantage of being from sustainable sources.

Sheep’s wool

∙ Wool is classed as a hygroscopic fibre and therefore can absorb moisture, in fact more than any other natural fibre meaning its insulation properties do not vary with changing humidity unlike some fibre glass products [3].

∙ The high elasticity of wool fibres means that over time it will not settle, and therefore no performance will be lost.

∙ Has a very high fire resistance, it will extinguish itself if it is set on fire.

∙ It is estimated to use less than 15% of the energy used to produce man made synthetics such as glass fibre insulation.

∙ It repays energy costs approximately five times sooner.

∙ Wool can absorb and breakdown various harmful airborne pollutants such as formaldehyde and nitrogen dioxide [4].

Straw

∙ Can be used as part of the building’s structure and therefore can reduce the amount of timber required by half.

∙ If the straw bales are compressed and sealed with plaster it proves to be fire resistant.

∙Very low embodied energy, cheap to use and readily available.

Hemp

∙ Naturally resistant to fungus and insects.

∙ Much like wool it is a breathable material and therefore is able to absorb and release moisture to help regulate internal humidity.

∙ Insect and vermin resistant.

Cork

∙ Naturally resistant to rotting.

∙ Does not support combustion.

Cotton

∙ Can be sourced from the plant or alternatively from recycled clothes such as denim.

∙ Similar insulation properties to fibreglass but does not contain formaldehyde, a substance linked with some types of cancer.

∙ Breathable, like hemp and wool.

∙Insect repellent.

These materials are just some of the recyclable and sustainable materials that can be used for home insulation. On top of the given advantages, all the above have shown to be effective insulators, having an insulation value above that of current building regulations and in many cases having insulation properties greater than that of man made synthetics.  These natural materials not only help reduce C02 production by reducing energy usage in households, but many in fact absorb C02 before their life as insulation.  For example, hemp which as a plant absorbs C02, has been proven that for every cubic meter of hemp insulation produced, roughly 13 kg of C02 is absorbed [5].

With the housing sector accounting for somewhere in the region of a third of the country’s carbon footprint according to the Department of Energy and Climate Change [6], effective home insulation should not be disregarded by home owners and the government.  This combined with rising energy costs makes these sustainable alternatives to home insulation a serious consideration.

[1]https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/49403/7154-stat-release-est-home-ins-oct-2012.pdf

[2] http://www.ornl.gov/sci/roofs+walls/insulation/ins_01.html

[3] http://www.thermafleece.com/wonders-wool

[4] http://www.sheepwoolinsulation.ie/why_wool/

[5] http://www.ecologicalbuildingsystems.com/products/natural-insulation/

[6]https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/48195/3224-great-britains-housing-energy-fact-file-2011.pdf

Typical tyre compositions found in the EU [3]

Environmental Risks

Heavy metals and pollutants that form only small percentages of the total composition of tyres such as lead and zinc, have the potential to leach into groundwater, the longer a tyre is left to breakdown the greater the chance of toxins being released into the environment. Many tyres at the end of their life are shredded, whilst this may aid various end of life processes such as recycling and transportation, if left exposed the shredded material will more readily leach toxins into the environment due to an increased surface area.

Discarded tyres also have a tendency to collect water which in turn can act as breeding grounds for mosquitoes should the water become stagnant.  The mosquitoes can then act as a transmitter of various vector-borne diseases such as malaria and dengue fever.

Tyres also pose a fire risk, with the composition meaning tyres will readily combust, the emissions of which pose a distinct threat to human health.  Emissions given off from burning tyres are known to contain toxins and particulate matter that will have a detrimental effect on the human respiratory system [4].

An incident that occurred near Knighton in Powys, Wales in 1989 highlighted the environmental impact tyres can have if managed incorrectly. The landfill site was holding somewhere in the region of 10 million tyres, which at the time was legal. The tyres caught alight and astonishingly continued burning until 2001, lasting a total of 13 years. [5] During this time leachate discharged from the landfill site entered the River Teme, affecting local water supply and freshwater habitats.  The site itself remains heavily contaminated however impermeable barriers and settlement tanks are now in place to contain the leachate and restrict any from entering local watercourses.

Whilst at the time the of the Knighton incident, sending waste tyres to landfill was legal, the practice was outlawed by the European Union in The European Landfill Directive [6] in 2003 who later went on to ban shredded tyres from being and landfilled in 2006. The only exception being ‘bicycle tyres and tyres with an outside diameter above 1400mm’.

Options Available

With EU law now banning the landfilling of tyres, ways of reusing and recycling end of life tyres have been developed over the years.

Before recycling a tyre, some tyres have the option to be retreaded. Retreading tyres will naturally extend the life of a tyre therefore reducing the pressures involved with environmentally reusing and recycling of end of life tyres.  Retreading is already widely used on plane and heavy good vehicle (HGV) tyres, and if the tyre frame stays intact, larger tyres such as those used for plans and HGVs can be retreaded up to four times. However, a car tyre can only be retreaded once.

One of the main techniques used for end of life tyres is shredding or crumbing which reduces the tyre into small enough pieces to fit various applications.  For example, the rubber crumb is used on many sports surfaces to form a synthetic turf, it can be also be used for brake linings, livestock mats, carpet underlay and as an additive to asphalt for road surfacing.  Applications for shredded tyres can also be found in the construction and civil engineering industries.  Tyre derived aggregate as they are known are largely used as a backfill material. End of life tyres have also found applications in the marine environment.  Tyres have been used to create artificial reefs and used for coastal defences. In both cases the tyres are usually compressed together to from a large bonded blocks of tyre material.

Tyres can also be used to fuel kilns in industries such as steel production, and used in cement kilns in the concrete industry.  Using tyres as a carbon source for burning does have its advantages, for example the kilns are capable of consuming whole tyres making them an easy way to reuse end of life tyres, and the tyre material has a calorific value 20% more than coal.  Despite the advantages, there are concerns about the emissions given off when using tyre material as a fuel in such a process.

An alternative method to incineration of waste tyres uses a contained oxygen free environment to heat the material. This process is called pyrolysis and noticeably reduces emissions. The heat breaks down the various compounds in the tyre material in a similar way to the fractional distillation process used when producing petroleum.  The products of tyre pyrolysis include fuel oil, carbon black, steel wire and small amount of non condensable gas. The fuel oil accounts for between 40 and 45% of the final product and can go on to be used in other industrial or commercial processes. Around 35% of output is carbon black which can be reused in numerous applications in rubber product manufacturing. The steel wire totals around 10 to 15% of the product, this can be sent to scrap dealers and recycled elsewhere, whilst the gas accounts for between 10 and 12% and can also be burned to produce energy [7].

It should be noted that a tyre’s main environmental impact comes during its main life where it impacts the vehicles fuel consumption.  Taking into account a tyres fill life cycle, it is estimated the in use fuel consumption accounts for 75.2% of its environmental impact [8].

All major tyre manufacturers are now producing ‘greener’ tyres, with Pirelli claiming their latest eco tyre has a reduced rolling resistance of 20%, reducing overall fuel usage by up to 4%.  The materials used in construction claim to reduce the environmental impact during production, use and end of life, and the overall life of the tyre is meant to average 30% longer.  The industry is clearly making steps forward taking into account the whole life cycle of the tyre. However with growing numbers of vehicles on the road, the tyre recycling industry will have to take further steps forward to keep up.

Find out more ways you can help reduce your environmental impact.

[1]https://www.gov.uk/government/publications/vehicle-licensing-statistics-q2-2012

[2]http://www.environment-agency.gov.uk/homeandleisure/waste/138215.aspx

[3]http://www.etra-eu.org/index.php?option=com_content&view=article&id=77&Itemid=66

[4]http://greenliving.nationalgeographic.com/environmental-impacts-throwing-away-tires-20116.html

[5]http://www.wao.gov.uk/assets/englishdocuments/Environment_Agency_Wales_Waste_Management_agw_2004.pdf

[6]http://www.central2013.eu/fileadmin/user_upload/Downloads/Document_Centre/OP_Resources/Landfill_Directive_1999_31_EC.pdf

[7]http://www.pyrolysisoil.net/PRODUCTS_SOLUTIONS/Tire_Pyrolysis_Plant/Continuous-Scrap-Tire-Pyrolysis-Plant.html#.UYitr0rcA7Z

[8] http://www.nokiantyres.com/environmental-effects-while-using-a-tyre

With many of the worlds automotive giants including the likes of General Motors, Ford , Toyota and Honda introducing new ranges of electric vehicles (EVs) to their fleets, one would be forgiven in thinking the future of motoring lies with these battery powered electric cars.  Further incentives to buy into this evolution of the automotive industry are given by the UK government who offer to cover 25% of the cost of an EV up to a maximum of £5,000. At the time when this grant scheme was introduced, the then Transport Secretary Phillip Hammond lauded 2011 as ‘the year the electric car took off’ [1].  Similar actions are being mirrored in other major countries such as the US where new EVs are subject to federal tax credits as well as additional incentives from states such as California, in China where subsidiaries are paid to manufactures of these vehicles, and in Japan where incentives are also offered by considerably lowering the cost of EVs to the public.

These past few years have also seen considerable increases in the levels of technology associated with EVs, notably with the lithium ion batteries used to power them. Nissan boast that their new Leaf has an improved range of 124 miles and with a charge time as low as 4 hours with the ‘S charge package’ [2].  Given that REVA’s original G-Wiz which introduced the concept of plug in motoring in 2001 could manage just 50 miles with a full charge time of up to 8 hours [3], it is clearly evident that things are improving. These figures however, may not be easy to accept for the average petrol or diesel fuelled car driver of today.

Valid arguments have been put forward against the EV stating that when the full life cycle for production to end of life of an EV is compared to that of an ordinary petrol fuelled car, an EV will offer little in the way of environmental benefits.  A study put forward by The Norwegian University of Science and Technology in the Journal of Industrial Ecology highlights that the production of an EV has approximately twice the environmental impact than that of an ordinary car [4, 5].  Therefore in order to regain some of its green credentials it must run largely on electricity from clean sources.  When taking into account the source of electricity, the current mix of renewable and non renewable sources in Europe do offer a 10 to 24% decrease in the carbon footprint of the vehicle according to the study.  However, for nations such as China, still predominantly fuelled by conventional fossil fuels, it is thought that EVs may not actually offer any environmental impacts at all, in fact it may even be the case that they result in a larger carbon footprint that an ordinary car. Many who argue the case against the EV claim the answer to the future of motoring lies with the hydrogen fuel cell powered cars.  The production, transport and storage of hydrogen however all pose considerable barriers to make it a greener way to power our cars.  For example, in order to use hydrogen for this purpose it must be 99.999% pure [6].  The production required needs considerable energy input to the extent that in some cases it is thought to take more energy to produce than it eventually provides. Other arguments against also include the fact that hydrogen has a propensity to leak through most materials owing to the fact it is the smallest molecule in existence.  Therefore a whole new infrastructure for transport and storage would be required before any hydrogen fuel cell powered cars could be used on a global scale.

What becomes apparent amongst the all the governmental schemes, industry advertisements and even social pressures is that one form of technology seems to be being left behind and forgotten by many in the automotive industry largely in favour of plug in electric vehicles and to a lesser extent hydrogen cars. This technology being liquid nitrogen.

The basic concept behind the use of liquid nitrogen to fuel a car is that the pressure created when liquid nitrogen is converted to its gaseous form can be used to drive a piston or turbine engine and thus run a car.

Advantages of liquid nitrogen over its automotive fuel counterparts are numerous.  They include the fact that production of the cars would be likely be cheaper and less harmful to the environment without the need to produce numerous lithium ion batteries, therefore not producing the same emissions during production. The materials used in construction would also not need to handle the same high temperatures a battery powered car experiences, therefore allowing for the use of cheaper materials. [6] Some figures give the cost of a liquid nitrogen car with comparable range to a Nissan Leaf at little over half the cost of the EV [6].  Moreover, much of the infrastructure and the technology required to get fuel from production plants into cars already exists because liquid nitrogen is already widely used as an industrial coolant.  Granted the infrastructure would need a vast overhaul, but at least the same issues associated with the use of hydrogen transportation and storage do not arise.

Seemingly on of the most important issues after cost for the everyday motorist is refuelling time.  Trying to comprehend even the most optimistic targets given by EV manufactures such as Nissan for charging time seem hard when we are used to the two or three minutes in takes to refuel an ordinary petrol or diesel car.  Happily liquid nitrogen cars would require the same fast process we have all become accustomed to.

Despite all the arguments for and against EVs, hydrogen cars and liquid nitrogen cars, it appears that for the time being car manufactures are choosing to invest in the electric vehicle.  Let us just hope all the money and effort which has been ploughed into the technology associated with EVs is worthwhile and history doesn’t show battery powered vehicles to be somewhat of a dead end.

[1] http://www.guardian.co.uk/environment/2011/oct/21/electric-car-uk-sales-sputter

[2] http://www.nissanusa.com/electric-cars/leaf/

[3] http://www.thegreencarwebsite.co.uk/blog/index.php/g-wiz-ac-electric-cars/

[4] http://www.bbc.co.uk/news/business-19830232

[5] http://www.ntnu.edu/news/2012-news/shocking-electric-car-news

[6] http://www.economist.com/blogs/babbage/2012/10/nitrogen-cycle