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by Bill Weaver
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Ternion Bio’s BioBlade system uses Harvel® EnviroKingUV® pipe to create state-of-the-art
photobioreactor systems. |
As America awakes cautiously toward economic recovery in the new year, there is an underlying sense of optimism related to the expanded use of renewable energy in this country.
Although the movement is global in nature, here in the United States, major emphasis has been placed on the development of alternative energy sources out of necessity to help alleviate the United States’ dependence on foreign oil. That desire, combined with America’s spirit, innovation and technical know-how have pushed the United States to develop more efficient means of harvesting our renewable energy resources. Significant technological advancements have recently been made in the development of solar, wind, geothermal and biofuels as effective alternative energy sources to fossil fuels. Although most experts agree that it will likely take a combination of all of these technologies working together to eventually rid our dependence on foreign oil, the benefits of doing so are obvious. The alternative energy resources described are renewable (green energy), they are rapidly becoming more cost effective, and their use greatly reduces our impact on the environment.
So where does plastic pipe fit into renewable energy applications? Actually in numerous ways, some of which include the manufacture of solar panel components (high purity plastic pipes convey ultra pure water used in the production of photovoltaic (pv) components). Once panels are installed, solar energy can be converted to electricity that is used to heat water, which is then conveyed through plastic piping systems to the point of use (i.e. heated swimming pools). Plastic pipe is also used in underground geothermal applications due to its inherent corrosion resistance and good insulating properties necessary in heat transfer applications. Some plastic piping is even used as integral components in the construction of wind turbines.
One very promising green energy technology where the use of plastic pipe is an integral part of the process for fluid handling applications involves microalgae as a potential biofuel source. Microalgae, known as a third generation biofuel, have several advantages over alternate biomass sources that are used to create biofuels such as corn (ethanol) or soybean (biodiesel). There are thousands of strains of algae that thrive in both fresh and salt water environments. Certain strains of microalgae are very high in oil content as a biofuel source. As a fuel source, microalgae have the potential to yield much greater amounts of oil per acre per year than other biomass sources. In addition, the use of algae does not result in food crops being used for biomass, is highly adaptable to extreme conditions and can be grown in arid climates, does not require the use of high valued agricultural land, does not require the use of potable water for cultivation, and is a completely renewable energy feedstock.
Basically algae require water, sunlight, carbon dioxide (CO2) and nutrients such as nitrogen to thrive. Through photosynthesis, algae capture CO2 and convert it using the sun’s energy into carbon containing energy molecules such as sugars, starches and fats. The byproduct from the photosynthesis process is oxygen. Many strains of microalgae produce oil (lipids) naturally as part of the photosynthetic process. Once separated from the algae biomass, this oil can be harvested into biocrude which can then be refined through conventional oil refining processes into biodiesel, bio-gasoline, bio-jet fuel and biochemical feedstocks (even additives for plastics). After oils are separated, the leftover algae biomass can be utilized to produce nutraceuticals, fish and animal feed and other beneficial products. Other industry experts claim that certain strains of algae have also been cultivated that produce ethanol as a direct byproduct of the photosynthesis process.
Microalgae can be cultivated in open ponds or in closed piping systems comprised of transparent plastic pipe exposed to sunlight, known as a photobioreactor or PBR.
Although great strides in separation and harvesting technologies have very recently been made, the commercialization of microalgae to biofuel is currently in its infancy and barriers to cost effective scalability remain. Some experts state that open ponds are the only viable means to cost effectively produce the volume of microalgae necessary to be competitive with fossil fuels. Others claim closed loop photobioreactors are more efficient as they are not susceptible to contamination from unwanted species, the growth environment can be tightly controlled to optimize yield rates, specific algal species can be selected depending on the climate and resources available, and some even claim that species have genetically engineered to produce the desired end product.
This is where another application of plastic pipe for fluid handling in the renewable energy market comes into play: the construction of photobioreactors.
A photobioreactor can basically be described as an enclosed vessel where light, nutrients and temperature can be controlled to cultivate microalgae. Photobioreactors can consist of multiple runs of interconnected parallel pipes, vertical pipe runs, or stacked horizontal runs of pipe which are either exposed to direct sunlight, or to artificial light sources. Specialty ultraviolet resistant clear PVC plastic pipe in various diameters has been developed and optimized for this application, and is currently being used to construct commercial scale photobioreactors.
The plastic pipe is used to circulate the microalgae culture medium which is comprised of water, dissolved CO2, and nutrients (typically nitrogen and phosphorus) while exposing the medium to the light source. Once seeded with a selected microalgae strain, proper mixing of the solution is critical to ensure that the microalgae are exposed uniformly to the growth medium and receive the proper amount of light to improve photosynthetic yields. This can be done with proper system design that can be used to control flow rates while optimizing light exposure.
Specialty clear PVC pipe can provide a viable cost effective pipe material for circulating the microalgae culture due to its beneficial fluid handling characteristics that include: exceptional corrosion resistance, smooth interior walls for unimpeded flow and reduced sediment build-up, good pressure bearing capability, improved optical properties, fast reliable solvent welded joining techniques and ease of handling and installation.
Regardless of which cultivation method may ultimately prevail, there is a current market need that is helping to drive commercialization of algae — carbon capture. Carbon capture has become a major focal point with energy companies, refineries and large industries committed to reducing greenhouse gas emissions. Recognized as a pollutant by the Environmental Protection Agency, carbon dioxide (CO2) is being recycled by companies into useful products that can be used across an array of industries. Recycling CO2 emissions as food for algae, instead of dealing with emissions by pumping them into depleted oil fields, burying them underground or at the bottom of the ocean, allow the CO2 emissions to serve as the catalyst for the growth of algae, which then becomes the raw material for a wide range of beneficial products.
California’s Ternion Bio Industries utilizes specialty clear PVC piping combined with scalable technology to create large-scale photobioreactors to convert carbon dioxide into a clean combination of algae and oxygen. The photobioreactor is constructed of steel framing, specialty clear pipe, and pumps in which carbon dioxide is mixed with other nutrients to feed algae.
Ternion Bio’s state-of-the-art photobioreactor system is based on a unique design that combines the best of Ternion Bio’s own research with what the company has learned from the problems encountered by companies with similar interests. “When developing our photobioreactor system,” says Chris Schuring, chief operations officer at Ternion Bio, “we examined the problems that other algae companies faced when trying to scale, then adopted a modular approach that overcomes these scalability issues.”
The inner workings of Ternion Bio’s photobioreactor — the algae and their growing environment — are contained in smaller BioBlade™ units, open metal frames containing stacks of interconnected horizontal runs of specialty clear PVC pipe that circulate the algae. Each BioBlade slides into the photobioreactor structure in a fashion similar to a computer server “blade” sliding into a chassis.
The photobioreactor system uses more than 700 gallons of treated water per BioBlade unit, and each BioBlade has its own 250-gallon water tank and pump. If one BioBlade experiences mechanical problems, its isolation from the other BioBlade reactors means that the rest of the photobioreactor system will not be affected. Each BioBlade unit operates independently from the entire photobioreactor, while supporting the entire system as well.
The specialty clear PVC piping system provides the backbone of both each BioBlade unit, and each photobioreactor unit as a whole. As such, the pipe used must be extremely durable and perform well on a daily basis. In addition to its UV resistance properties and its sunlight transmission characteristics, the clear piping selected for PBR construction must also exhibit exceptional corrosion resistance and good pressure-bearing capability.
Using photobioreactors as a modular approach to carbon capture at coal fired plants and similar industries enables algae to become an on-site flue gas scrubbing system that removes CO2 and other greenhouse gases from the smoke stack right at the carbon source, and requires less of a foot print than open ponds. In addition, waste water from the plant can be utilized to provide the water and nutrients needed to supply and sustain the photobioreactors while producing algae that can be harvested and processed into other beneficial products.
Specialty ultra violet resistant clear PVC piping provides an optimum piping material for the construction of photobioreactors compared to alternate transparent piping materials, such as glass or polycarbonate. This due in part to PVC’s proven leak free joining techniques, durability and installed cost savings. Its unique composition allows the light wave lengths beneficial for algae growth to pass through, while preventing UV wave lengths that are damaging to conventional clear PVC to penetrate the plastic.
As demonstrated by the context of this article, plastic pipe will continue to play a vital role in how future technologies evolve and unfold with advancements in technology; including the renewable energy markets. The continued development and use of renewable energy sources is crucial to U.S. energy security, and the use of plastic piping for fluid handling applications is proving to provide real solutions in these evolving markets. And who said PVC plastic pipe isn’t green?
Bill Weaver is director of technical services for Harvel Plastics, Inc. For further information, contact Harvel Plastics, Inc., P.O. Box 757, Easton, PA 18044-0757 USA; (610) 252-7355, e-mail: harvel@harvel.com, www.EnviroKingUV.com.
Harvel and EnviroKingUV are registered trademarks of Harvel Plastics, Inc. BioBlade is a registered trademark of Ternion Group LLC.
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