Talk about cutting out the middleman! A California company called LightManufacturing has figured out a way to fire up a plastic molding process with a concentrated solar power system, and the kicker is the system has no solar cells to generate electricity. Instead, heliostats (aka mirrors) provide all the direct solar thermal energy needed to melt plastic pellets into a kayak, lawn furniture, or other plastic product.
Roto-Molding and Fossil Fuels
The molding process itself, called rotational molding or spin casting, is a standard industrial process that consists of heating plastic pellets in mold affixed to a rotating device, which sits in an oven-like space. When exposed to heat, the melting pellets coat the inside of the spinning mold to a uniform thickness.
The process is economical as far as manufacturing systems go, but it is energy intensive. LightManufacturing estimates that energy to heat the ovens can add up to 30 percent to the final cost of a product.
Conventional roto-molding poses a particular dilemma for manufacturers of green products, such as recycling bins and water barrels. The typical roto-molding oven is heated with natural gas, and that involves the manufacturer in a raft of unsavory issues associated with the natural gas drilling method known as fracking.
That includes water contamination, methane emissions from drilling sites, earthquakes, and other phenomena best avoided by companies trying to build a socially and environmentally responsible image.
Heliostats and Solar-Powered Manufacturing
A roto-molding system that operates on alternative energy would eliminate all of that negativity, and heliostats provide a cost-effective means of obtaining clean energy from the sun.
In a conventional concentrated solar power system, an array of heliostats focuses sunlight on a central tower. Heat from the tower is eventually transferred to a turbine that generates electricity.
In LightManufacturing’s molding process, the heliostats focus sunlight directly on the ovens. The end result is a system that costs less than typical gas-fired roto-molding systems.
Part of the savings is due to the heliostats themselves, which were selected for their low price, efficiency, and durability. They can be flat-packed, which also saves money on shipping.
Another part of the savings comes from a wireless control system that enables the heliostats to catch the maximum amount of light as the sun moves across the sky. The software can be run from any laptop, which provides another layer of efficiency and mobility for facility managers.
Also helping to save costs is the system’s scalability. Since no central tower is involved, the heliostat array can be scaled down enough to fit on or near the property of a small manufacturing facility, or scaled up for larger operations.
Manufacturing the Future
LightManufacturing’s system dovetails neatly with President Obama’s manufacturing initiatives, which are designed to help the U.S. manufacturing sector compete in a future defined by alternative energy, energy efficiency, and advanced systems, including wireless technology and robotics.
Also boosting the system’s green cred is its adaptability to different plastic feedstocks, including recycled plastic, biodegradable plastic, and bio-plastic, as well as conventional pellets.
Image: Courtesy of LightManufacturing.
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Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.