Emerging Technologies
Emerging technologies for use with steel roof and wall cladding : Solar
New Zealand has long been a home for the use of “alternative” energy generating technologies, both because of the scattered nature of settlement and the Kiwi DIY attitude. Photovoltaic electricity has been one of these technologies, and one that is currently changing rapidly.
Here we look at the potential use of steel roof and wall cladding materials as the base for several new photovoltaic coating technologies. These concepts use the entire roof area for integrated electricity rather than the current discrete small-area panels.
Co-operative research and development is taking place around the world with one focus on third generation solar technologies which are now fast gaining momentum, overtaking the first and second generation solar technologies of the hard panelled crystalline silicon and the flexibly thin-filmed amorphous silicon.
Australian company Dyesol is a global leader in third generation solar technologies. The Canberrabased company has developed industrial coatings for steel or glass that mimic the photosynthesis that creates energy in plants. Their Dye Solar Cell (DSC) process, developed originally in Switzerland, is a photovoltaic technology enabling metal, glass and polymericbased products used in the building, transport and electronics sectors to generate electrical energy.
The process involves using a screenprinting machine to coat a layer of very thin titania (titanium dioxide) strips onto the surface of a metal, glass or polymeric product. Titanium dioxide is a plentiful, electricityconducting material commonly used in toothpaste and paint. When it dries, it leaves a porous coating of nanoparticles with an extraordinarily large surface area created by the very thin strips.
If this surface is, for example, glass, the product panes are then dipped in a dye containing the metal ruthenium and fused to a second piece of glass coated in electrolyte. The ruthenium dye absorbs available solar energy in a similar way as chlorophyll does, taking in electrons and transferring them to the titania layer and so creating electricity.
In early 2007, Dyesol signed a $1 million contract with Corus (now Tata Steel) to assess the feasibility of incorporating dye solar cells into its prefinished steel-roofing materials, with a view to generating clean power from the cladding. By the end of 2007, it was determined that Dyesol's cells could feasibly be printed on the surface of a coil of steel on a paint-coating production line at three to five metres per second.
Meanwhile in Europe, having successfully trialled Dyesol’s dyesolar- cell technology, Tata Steel is currently working with researchers at Swansea University to produce sheet steel treated with a sensitive coating of solar cells in the form of a photovoltaic paint – a liquid paste – which is made up of a layer of dye and a layer of electrolytes.
Altogether, the sheets of steel get four coats of solar paint — an undercoat, a layer of dye-sensitised solar cells, a layer of electrolyte or titanium dioxide as white paint pigment and lastly, a protective film. The four layers of the solar cell system paste are applied in rapid succession to steel sheets when they are passed through the rollers during the manufacturing process.
The future of steel is looking bright as the global steel industry assesses and develops these breakthrough technologies with the potential to significantly reduce greenhouse gas emissions and improve energy efficiency, while underpinning steel’s role in a sustainable future.
These developments come at an opportune time for New Zealand Steel, where improvements in energy efficiency in the 30 years since the early days of production have reduced the amount of energy required per tonne of raw steel by 50% – leaving only marginal room, planners estimate, for further improvement on the basis of existing technologies.
Competition to develop solar technology has been sharpening over the past decade. The Victorian Organic Solar Cell (VICOSC) consortium announced in 2010 that within three years it aimed to develop flexible, large area, cost-effective, reel-to-reel printable plastic solar cells, creating a prototype of organic solar cells printed on plastic. The consortium, which includes BlueScope Steel, has moved away from solar cells based on silicon to dye-sensitised mesoporous nanocrystalline titania cells, or polymer-polymer bulk heterojunction solar cells, believing that these technologies could be harnessed to generate low-cost flexible solar cells via traditional printing methods. Addressing the Ai Group Technology Summit 2012 in Melbourne in October, VICOSC Project Co-ordinator David Jones spoke of the consortium’s work in developing these printable organic solar cells.
He noted that global energy demand is expected to at least double in the next 50 years and postulated that energy is the real currency of the world. Providing solutions to this increasing demand, he emphasised, was both essential and challenging. He said VICOSC aimed to develop a pre-commercial product by 2014 offering high speed printing of large areas at low cost.
He suggested that these lowcost printed solar cells would be integrated into building materials such as roofing materials, sheet or tiles and into shading material as well as being incorporated into consumer goods.
At the start of printing trials in early 2009 Australian Senator Kim Carr is reported to have commented: “To be able to manufacture flexible, organic solar cells which are ‘printed’ on to polymer in much the same way as money is made, quickly and cheaply, has enormous potential.”
Meanwhile in June 2012 solar film developer Heliatek announced from Dresden, Germany that its transparent films could be used between glass sheets in double glazed windows to generate electricity. These windows will look like tinted glass as the unique vapour deposition technology for the solar films allows for a
homogeneous coating of the solar layer without any distracting patterns or irregularities. Thus, transparent solar films, integrated into a building’s design, will enable building glass to become energy harvesters.
Founded in 2006 and based in Dresden, Germany, Heliatek GmbH engages in the development and production of organic solar cells and is recognised as a technology leader in the development of organic photovoltaics (OPV) based on small molecules, and in the manufacture of organic solar films.
Earlier, an August 2012 news article reported that Heliatek’s new ultralightweight, transparent solar films could be integrated into building and construction materials, car roofs and street furniture. The first batch of solar films manufactured would be used for concrete façade projects and for pilot products and prototypes.
Heliatek has already announced a joint development agreement with elastic formliner and mould designer and supplier, RECKLI GmbH, whose formliners are used in precasting factories and in castin- situ concrete. The February 2012 agreement will see Heliatek’s film used in concrete façades.
In New Zealand the over-riding message from the Sustainable Electricity Association of New Zealand (SEANZ)’s October 2011 conference was that smallscale renewable DIY power is becoming mainstream and that every home and business could potentially be generating its own grid-connected electricity. SEANZ’s CEO Charmaine Watts maintained that the small-scale technologies of DIY power such as solar PV, small wind turbines and micro hydro give consumers more control over their electricity supply and demand while directly contributing to reducing green house gases.
In an article in Handymanmagazine. co.nz, Jan 2011, Sandra Bridekirk suggested installing even a small solar power system to capture sunlight and convert it into energy could save up to 1.5 tonnes of carbon dioxide a year – the equivalent to taking a car off the road. Solar power systems, it is suggested, can help increase the value of the home.
One company walking the talk is Hubbard’s Foods in Auckland. In mid-2010 the company installed a 160 solar panel construction covering 227.5m2 which aimed to generate 29,000 kW/h of electricity a year to be used to power the lighting for the finished goods warehouse.
While solar energy has not come cheap at this time, Chairman Dick Hubbard maintains this was not a short term commitment, reckoning that 20 years hence the panels would be functioning at similar levels to those presently achieved – no matter what happens to the weather, as the panels are able to function on a cloudy day provided that they are kept clean.
Auckland Airport’s commitment to sustainability sees a photovoltaic solar array of 300m2 solar panels installed on the roof of the new international arrivals hall which generate enough solar energy to power the arrivals corridor lights during the day, providing an estimated energy generation of 49,500 kWhr per year, equating to 16 days’ worth of power savings energy. Also on the roof are solar water heating panels which provide pre-heating water in the hot water system. This solar energy is estimated to generate energy savings of approximately 15,000 kWhr per year.
Several manufacturers are already successfully marketing and installing first and second generation solar systems, some specialising in flexible solar technology, in a product range that includes portable solar chargers, BIPV solutions (Building Integrated Photovoltaics), military applications and emerging innovations. This flexible system, which can be in the form of a solar shingle, can be installed on any roof under the sun – from flat to curved. A standalone business within the BP Group, BP Solar has been dedicated for 40 years to the development, marketing and distribution of cutting-edge solar technology. BP launched its international solar canopy programme in 1999 and now has more than 400 sites with solar canopies throughout the world. Sixteen of these are in New Zealand, the largest at Rodney’s Dairy Flat Service Centre.
However this one-time industry pioneer, BP Solar, announced in December 2011 that it was closing: “The major global solar markets have experienced tremendous change over the past few years and we have been unable to generate the necessary returns to continue our operations.”
The market reality is that as more manufacturers produce a wider choice of solar options, so does the cost reduce to consumers: the price of solar photovoltaic panels is reported to have dropped more than 50% in the past two years. BP Solar is just one of the casualties in this rapidly consolidating solar industry. Parent company BP does, however, remain committed to alternative energies in onshore wind as well as biofuels.