Plastics Reshape Energy Landscape
February 02, 2011
PLASTICS RESHAPE ENERGY LANDSCAPE by Evonik Cyro LLC
Plastics and acrylics are so ingrained in everyday life that we rarely think about all of their uses. Many of the more recent applications have taken on a “green” focus — from products that create and distribute power to others that simply allow us to use less energy in our homes and businesses. World energy requirements are mainly addressed by non-renewable resources. Oil, coal and gas however, are not carbon-neutral and fossil fuel sources will eventually run dry. That is why, in the fight to mitigate climate change, alternative energies are expected to comprise a larger share of the global energy supply. According to the Intergovernmental Panel on Climate Change (IPCC) report submitted to the United Nations, transparent plastics are particularly suitable for a wide range of alternative power generation methods.
The power of wind
Plastics have found a home on wind farms, where they are being used in a variety of designs. Many wind turbine blades are made from reinforced thermoplastics and thermosets because they are lighter and less expensive to manufacture than alternatives such as aluminum. The yaw and rotor bearing components within a wind turbine are now also being manufactured from plastic. The use of lightweight plastics for bearing applications is helping decrease friction and increase wind turbine efficiency.
Converting sunlight into energy
Harnessing the power of the sun and converting it into energy is another area in which plastics have shined. Solar modules are becoming more widespread in both business and residential settings. Some of these units incorporate special lenses that focus the incident sun rays so they can be converted into electrical energy. A lens and its cover require a material that transmits an extremely high percentage (90+ %) of light, yet is highly resistant to UV. Acrylic sheet is an ideal candidate because it meets these criteria. Its attributes also make acrylic well suited for other types of power generation, including solar collectors and solar updraft towers, which use sunlight to produce hot air that drives turbines. Light transmission is the most critical factor in systems that use solar energy to generate power. Certain types of acrylic with 92 percent light transmission or above are the best choice in these systems. Resistance to weather is another factor to consider. Once again, acrylic stands up to this test better than alternative materials. Plastics and acrylics offer other benefits too, such as being lightweight and hail resistant. In addition to offering performance advantages, acrylics can deliver aesthetic benefits. Plastic solar tiles with injection-molded acrylic covers appear identical to traditional clay tiles and conceal solar cells, making them visually attractive. Solar heat is another way in which the Sun is used as an energy alternative. Solar heat converts sun rays into heating energy, making it possible to enjoy a climate-friendly lifestyle without the demand for fossil fuels. For example, people can use a solar collector to harness the sun’s energy and heat a large hot water storage tank. While many different materials can be used as the lens of a solar collector, a highly reflective acrylic provides high transmission, cost efficiency and other benefits.
Sometimes — especially during hot summer months — the sun can cause an adverse effect by overheating a living or working space. Allowing natural light in through traditional skylights or windows may make a work environment unpleasant and force air conditioning systems to be in operation on an almost constant basis. Air conditioning units are extremely energy intensive and are, therefore, harmful to the global environment. They can also hurt the bottom line of a company, as well as an individual, because of their operational costs. However, separate studies by the Heschong-Mahone Group and U.S. Department of Energy confirmed the psychological benefits of natural light. In fact, students of schools utilizing daylighting practices tested 21 percent higher in their test scores and grades than schools that relied on manufactured lighting sources. Additionally, the studies confirmed that daylighting can positively affect retail buying habits. According to the study, stores that utilized daylighting practices had 44 percent higher sales than stores without daylighting. Based on these findings, building and facilities managers, especially in warm summer climates, must find a balance between the need for natural lighting and the negative effect of heat buildup. Fortunately, by utilizing certain materials and practices, the amount of heat that enters via a skylight or window can be reduced without inhibiting natural light from illuminating a room.
Reduce heat, increase natural light
Light domes manufactured with an IR reflective acrylic material offer the ability to significantly limit the heat gain of the building while delivering the required amount of light. These units generally contain an inner and outer dome separated by an air gap. Additionally, it is common for one of the inner layers to be made from frosted white acrylic that diffuses light over a larger area to eliminate areas of harsh, direct sunlight and dark shadows. In some cases, acrylic sheet with heat-blocking properties will reflect nearly twice the amount of solar energy in the IR range, while continuing to transmit the same amount of visible light. When replacing standard skylight white diffusing materials with a heat-reducing acrylic, the heat build-up in a building or home is nearly cut in half, while light transmission remains the same. A key benefit to such an acrylic is that it lowers operational costs. Using a heat-stopping material in a skylight rather than glass or standard acrylic can save as much as $0.77/sq. ft. per year in air conditioning costs. In scenarios in which air conditioning is not used, the number of high-temperature days indoors is reduced by 30 percent, creating a much improved work environment. Daylighting has other benefits. Because of the earth’s rotation around the sun, natural lighting offers moving light within an office rather than stagnant artificial light. Using acrylic sheet in this application not only keeps heat out, it prevents bleaching of carpets, furniture or other objects positioned near the window or skylight. Plus, the shatter-resistant acrylic provides a safe alternative and the coated surface provides a relatively maintenance-free solution. Additionally, utilizing daylighting practices can generate points needed to achieve LEED certification, especially gold and platinum status. Many commercial building developers and owners are now adopting “green” practices and are looking to achieve LEED certification that can help the environment and provide tax benefits. Companies have developed tools that help architects and designers calculate the number of skylights appropriate for a particular building in order to generate the maximum amount of light while keeping the temperature moderate. They take into consideration factors such as the outside climate, building size, direction the building faces and desired energy savings. Currently, a number of major grocery store chains, home improvement stores and large shopping megastores have started to adopt these practices. In some cases, these outlets have achieved the coveted LEED platinum designation.
The use of plastics in the generation and storage of energy, as well as to prevent heat energy, are clear. The savings and benefits to use these materials clearly outweigh the costs associated with them. From solar panels that utilize a clear acrylic covering to daylighting products that reduce heat build-up indoors through IR-shielding, there are definite advantages compared to other materials. Add the psychological benefits of natural light, the ability to recycle these products and the weight ratio for transportation compared to other materials, and acrylic comes out as a clear winner.
Originally Published in the IAPD Magazine