Design Life-Cycle

Cole Creedon

Foster, Elisa

DES 40A

Professor Cogdell

Energy usage for a Basic Rainwater Collection System

Water, along with food are among the universal needs for human life, without sustained and reliable access to such resources we fail to fulfill some of the basic needs to foster a living, breathing cooperative society. Fast-growing, developed societies have resorted to massive infrastructure to support its growing population’s needs like dams, pipelines, and water treatment facilities, at great economic and environmental costs. Although these systems are only applicable in countries and geographic locations that have the funds as well as the political stability to properly develop and implement them. Even though water is an inherent need to sustain life, many people live in locations that lack direct access to infrastructure that wealthier societies often take for granted. Also, in light of global climate change, with rising concerns about severe droughts as well as large scale storm runoff, a strive for auxiliary means of collecting precious resources such as water are becoming increasingly important. As an alternative, we can look to basic rainwater collection systems as low-tech, low-cost means of sustainably capturing natural rainwater for long term use. This essay will look at how turning to simple rainwater water collection systems allow for a smaller environmental impact and compare the energy use of the materials incorporated throughout the lifecycle of the product from cradle to grave. Even though gravity-fed rainwater collection systems are low-tech and harvest a renewable resource the components that are used are often energy-intensive to produce and create some toxic chemicals at the end of their life cycle.

To fully understand the way these systems use energy, it’s important to first understand their components and what they are composed of. These basic Rainwater Collection Systems (RCS) come in many different forms but are composed of the same basic components. Our focus will be on small scale water reclamation for communities that may lack on-demand access to electricity and don’t have access to clean water via water treatment facilities. First, a means of capturing the rain as it falls over a relatively large surface area, simply corrugated steel to guide the runoff (fig 1). Next, the runoff follows a gutter, typically manufactured out of aluminum then trickles into common Poly-Vinyl Chloride (PVC) piping. From the PVC piping, the water goes through a filtration system using sand or charcoal filters, then finally into a storage receptacle commonly using a High-density polyethylene (HDPE) storage unit (1). The RCS models we are looking at efficiently utilize the energy potential of gravity acting on rainwater throughout the system to eliminate the need for pumps or electrical systems (1). The materials we used are low in cost, and accessible in most parts of the world including developing nations. An off-grid water collection system seems very low in energy use, which is correct although only once every component has been manufactured, transported, and installed does it begin using minimal energy. For example, lets look at the manufacturing of aluminum one of the components in the gutter element. Smelting is one of the most energy-intensive processes we use to manufacture items, superheating raw ore until they liquefy to shape them into all manners of objects. First, we need to understand aluminum at its raw components, which is formed from a claylike rock called Bauxite. Bauxite is mined at approximately ~.32kWh per kilogram of bauxite that is extracted from the Earth, using what’s known as the Bayer process, we refine the bauxite using caustic soda, or sodium hydroxide to separate the impurities of the bauxite and the aluminum compounds giving us purified aluminum oxide. Finally, we use the Hayer-Hoult process to smelt the pure aluminum oxide compounds into releasing pure aluminum ready to cast. The final phase is one of the most energy-intensive steps since the electricity needs to heat metal ore to the point of melting is incredibly high. For reference, even the more modern state of the art smelters, that are powered via hydroelectric energy use around 14.4 kWh per kilogram of pure aluminum produced (4). These modern foundries produce each kilogram with the same amount of tacit energy, which is the total energy usage at all stages of production including transportation of the energy source, feedstock energy as well as the onsite energy consumption. Comparatively some of the less modern foundries that are coal-fired still produce each kilogram of aluminum at 14.4 kWh, but have a tacit energy usage of 36.0 kWh per kilogram (4), so more than double the amount of energy to produce the same product. Currently, only about 40% of the foundries in the United States of America are powered from energy produced at hydroelectric facilities or other similar renewable energy sources. These are challenging aspects of raw resource processing because a vast amount of energy is lost as a result of heat, as well as using dirty energy sources like coal that are energy-intensive to extract and transport at pretty much every stage of use. 

The next facet of our ‘simple’ system is High-Density Polyethylene or HDPE. In the diagram cited below, HDPE is the storage receptacle that catches the cascade of rainfall from our aluminum gutter component. Polyethylene is one of the seemingly endless products from the petroleum industry that has permeated its way into our everyday lives. Prized for its resiliency due to HDPE’s chemical makeup creates a plastic that is highly resistant to temperature, cracking, denting, and moisture creating an impermeable membrane perfect for water storage. HDPE follows in the footsteps that a majority of petroleum products are formed from intense heat changing its chemical structure from standard petroleum. Created in huge vats, HDPE is a result of catalytic polymerization, from the extreme heat generated by electricity, in either a slurry or gas stage, slowly introduced to butene or hexene (6). Since HDPE has such desirable properties and applications in essentially all industries it has become one of the most widely used plastics in the world. Similar to smelting, the introduction of high heat requires a high energy input and is typically quite inefficient with usage as a result of heat loss. The embodied energy to produce HDPE fluctuates depending on facilities and access to materials but is around ~80 kWh per kilogram (5). Although with such a high energy input, it creates a product with lots of energy density and an extremely long lifecycle for most applications. The high energy density and chemical makeup allow for high potential for recyclability thus extending the lifecycle for such energy use even further throughout the first product iteration. The cost is relatively large to produce but it is rarely something that degrades easily so it is a great option to use for storage units for water tanks in our BCS. 

Our Basic Rainwater Collection System is a rather simple and widely applicable product in developing communities or countries that lack dependable resources like water and energy. The initial energy input is relatively large for a small quantity of product, but all of the components feature important characteristics that allow for a functioning water collection system without needing power. Our BCS makes up for the initial energy input being so great in exchange for product life, the aluminum gutters, PVC piping system leading into a large HDPE storage container all are long-lasting components to the system that will take ages to degrade beyond efficient use. In the purvey of many products used in today’s world, our choices for developing a basic rainwater collection system featuring these items make up a relatively eco-friendly life cycle with the ability to sustain use effectively for years beyond the large initial energy input. 

Bibliography

1. “Performance of rainwater harvesting systems in the southeastern United States” Resources, Conservation and Recycling, Volume 54, Issue 10, August 2010

2. “Energy use and carbon dioxide emissions from steel production in China” ‘Energy’ Volume 27, Issue 5, May 2002

3. “Roof rainwater harvesting systems for household water supply in Jordan” ‘Desalination’ Volume 243, Issues 1–3, July 2009, Pages 195-207”

4. “U.S. Energy Requirements for Aluminum Production” February 2007 

5. Ashby, M. F., 2013: Materials and the Environment – Eco‐Informed Material Choice, 2nd ed.,  Butterworth‐Heinemann, 616 pages. (HDPE poster notes)

6. “Journal of Cleaner Production”Volume 108, Part A, 1 December 2015, Pages 80-89

http://spendingsmarter.ca/assets/life_cycle_analysis.pdf PVC poster notes

 Foster Zellers 

Partners: Cole Creedon, Elisa Franco 

DES 40A 

Professor C. Cogdell 

Wastes and Emissions of a Basic Rainwater Collection System 

Water is essential to human life. Hence, it is important to ensure we always have access. Because of the immense demand for water, it remains a scarce resource in societies of all sizes around the world. While there are many challenges associated with the water supply, collecting and storing it has remained the most universal. Traditionally this has been easier in places that have greater access to resources, where it is possible to construct complex infrastructure for capturing water. This has proven to be effective and reliable, but not all places have the means to build such infrastructure. Thus, people in those places are forced to create their own, small-scale water capture systems with the resources they have access to. A basic rainwater collection system can be constructed on almost any home, from a variety of materials, with minimal labor requirements. Such systems can provide a reliable source of water for families, and even entire communities in need. While construction materials for a small rainwater collection system would be minimal relative to more complex systems, it is still important to know how the life cycle of these materials effects the environment and the surrounding community. This essay will be analyzing the wastes and emissions associated with basic rainwater collection systems used in developing countries. While most of the materials utilized by basic rainwater collection systems contribute to harmful wastes and emissions during manufacture, they can all be reused or recycled, even in developing nations, to reduce negative environmental effects.  

There are many different types of RCSs, but for the purposes of this essay, we will focus on a small-scale system designed to serve small groups of people in areas that many not have access to expensive materials or electricity. Clever design practices can allow a RCS to operate without the need for a pump, utilizing the potential energy provided by gravity to convey water through the system [Grafman, pg.7]. With these factors taken into consideration, we have defined our system of focus to consist of the following components:  

• A corrugated sheet of aluminum for rain to fall on 

• An aluminum gutter to collect the runoff 

• Various polyvinyl chloride (PVC) pipes & valves to control the flow of water 

• An aluminum mesh screen to filter large debris 

• A high-density polyethylene (HDPE) storage container such as a 50-gallon drum 

These materials (aluminum, PVC, HDPE) were selected for their low cost and accessibility in most developing nations.  

Most of the wastes and emissions associated with aluminum are the result of processing raw bauxite ore into aluminum. Aluminum is extremely common worldwide and is produced via a two-part process. The first part, known as the Bayer process, involves extracting aluminum oxide (alumina) from the bauxite ore. The second part: The Hall-Heroult process, involves smelting alumina in large reduction pots to extract pure aluminum. The most significant waste product is a “red mud” generated during the Bayer process, and contains potentially useful substances including iron, titanium, soda, and alumina. For every ton of alumina produced, one dry-ton of red mud is also produced [How products are made]. While the substances that red mud contains could potentially be useful, it is generally is very basic (high pH), high in salinity and contains a significant amount of technologically enhanced naturally occurring radioactive materials, or “TENORM”. Some red muds also contain high levels of arsenic and chromium, both of which are extremely toxic. The TENORM found in red mud includes uranium, thorium and radium. The toxic and radionuclide content of red mud makes safely extracting the useful substances extremely difficult and expensive. Although attempts at the secondary processing of red mud have been made, none have been economically viable. It is so risky, that secondary processing of red mud is completely banned in the US. It is usually dried, and then disposed of via mixing and covering with soil [EPA]. Red mud is truly a waste product. Two more byproducts are created during the Hall-Heroult stage of processing. Spent pot lining (SPL) is a carcinogenic substance containing high levels of cyanide and fluoride which builds up on the inside of the reduction pots [Drishti IAS]. Although classified as a hazardous waste, it has more recently found purpose being recycled. It is used to produce materials such as glass, ceramics and asphalt roof tiles. Carbon dioxide (CO2) is also emitted during the Hall-Heroult processing stage. As the alumina in the reaction pot undergoes an electrolysis reaction with the carbon pot lining, elemental aluminum and CO2 (which is released into the atmosphere) are generated [How products are made]. The CO2 emitted during this step accounts for a significant portion of the total greenhouse gas emissions during the life cycle of aluminum.  

Like aluminum, most of the wastes and emissions associated with PVC originate during the processing of precursor materials. The byproducts created during the production of PVC are particularly troubling due to the number of byproducts created, their spread and build up in the environment, and their toxic effects on life. The life cycle of PVC generates so many different byproducts that it would be impossible to evaluate, nor list all of them due to many lacking research or even identification. Researchers have however managed to identify chemically related groups of the byproducts which tend to share similar properties. The most harmful group of waste products are dioxins. These chemicals are known to cause cancer, reproductive impairment, neurotoxicity and immune suppression among other effects. Dioxins are unintentionally produced during the production of feedstock materials and once again generated when PVC and other vinyl compounds are incinerated, whether intentional or not (fires). Dioxins resist natural degradation, resulting in world-wide accumulation at high levels, and unobstructed spread via air and water. Being fat soluble, they also accumulate in animal life. Concentrations increase further up the food chain. Every human on earth has undoubtedly been exposed to dioxins. Phthalate plasticizers are another group of byproducts that cause similar issues to dioxins. In fact, the spread, accumulation and toxic effects of phthalates are nearly identical to that of dioxins. Phthalates are also released during the production and incineration of PVC, but unlike dioxins, they are released over the entire lifetime of PVC. A small amount of phthalate plasticizers constantly leech from PVC products into any substance that makes contact. And yes, this includes the water running through PVC pipes. The final significant group of chemicals emitted from PVC are heavy metal stabilizers. Metals such as lead and cadmium are used to extend the life of PVC products. These metals pose neurotoxic risks and are known to damage brain development and cognitive ability, even in very small doses. Like phthalates, small amounts of heavy metal stabilizers are released into the environment during the entire life of PVC [Thorton]. 

Most of the wastes and emissions associated with HDPE result from the extraction of ethene gas. HDPE is known to some as a “safe” plastic because of the minimal impact its manufacture has on the environment. It is thought to have a much lower impact than many other substitute materials. When looking only at the manufacture of HDPE, this appears to be true. It is created by polymerizing ethene gas with an organo-metallic catalyst [Sangwan]. Emissions released during this process include small amounts of ethane gas into the air; and benzene, toluene, and phenols into water [Harding]. These compounds tend to dilute and break down quickly and pose minimal environmental and health risks. Even so, the manufacture of HDPE is responsible for magnitudes fewer emissions of these compounds into the environment, than manufacturing an equal amount of polypropylene (a common, and comparable plastic) would emit. The most harmful aspect of HDPE is the primary precursor: ethene gas. Ethene gas is extracted via hydraulic fracturing (fracking). The fracking process is one of the worst offenders of environmental contamination of our time. Detailing all the negative environmental and health effects of fracking would require an erroneously long essay, and information that does not yet exist. The following information is an incomplete, extremely simplified and condensed summary. Fracking uses over 1000 different compounds to extract natural gas, which contains ethene gas. Of these compounds, 76% have no toxicity information available. Of the 24% for which some information is available, 65% are associated with developmental or reproductive toxicity [greenwood]. Many of the chemicals used during fracking are kept as closely guarded secrets and may never be revealed [Schipani]. Fracking releases untold amounts of toxic substances into water supplies, the air and the earth every day. The result of this, as it relates to HDPE, is that most of the waste and emission products generated during HDPE manufacturing stem from the extraction of ethene gas. Once the ethene gas has been obtained, manufacturing HDPE is a relatively “clean” process [Polyethylene: The Worlds Most Used Polymer].  

The common theme among aluminum, PVC, and HDPE is that most of the environmental waste and emissions produced while making these materials is generated during the extraction and/or precursor-processing stage of manufacture. For Aluminum, most of the waste is due to the extraction and processing of bauxite ore. For PVC, the lion’s share of emissions falls on the feedstock materials and bad disposal practices (incineration or landfill). For HDPE, the extraction of ethene gas causes most of the waste-product contamination. The solution to reducing environmental contamination resulting from these materials is to either eliminate the demand for water or substitute raw materials which need to be extracted and processed with recycled ones, in addition to properly disposing or recycle unwanted materials . As no amount of restraint or rationing will ever eliminate the demand for water, reusing and recycling materials is vital to the environmentally friendly collection of rainwater. Recycling or reusing these materials serves two purposes at once; it eliminates the need for precursor chemicals required for production, and reduces emissions associated with improper disposal. Recycling these materials produces byproducts and emissions of its own, and it is certainly not perfect, but the negative effects of recycling pale in comparison to that of producing virgin material. By eliminating the need for precursor extraction and processing, the total wastes and emissions associated with aluminum, PVC and HDPE are vastly reduced. In our world today, recycling these materials and purchasing recycled materials is more accessible than ever. As recycling has become a profitable venture in developing nations, recyclable materials like those listed are becoming cheaper and more easily accessible to locals [Lardinois]. If recycling services are a viable option for constructing, or disposing of a rainwater collection system, there is no good reason not to! Doing so will have a smaller environmental impact and leave the earth a slightly less-worse place.  

Bibliography 

Lardinois, Inge, and Arnold van de Klunder. "Plastics recycling in developing countries: a booming business?." Gate: questions, answers, information 3 (1995): 42-6.  

Grafman, Lonny. To Catch the Rain. Humboldt State University Press, 2017. 

“TENORM: Bauxite and Alumina Production Wastes.” EPA, Environmental Protection Agency, 6 Oct. 2017, www.epa.gov/radiation/tenorm-bauxite-and-alumina-production-wastes. 

“How Aluminum Is Made.” How Products Are Made, www.madehow.com/Volume-5/Aluminum.html. 

“Spent Pot Lining.” Drishti IAS, 18 July 2019, www.drishtiias.com/daily-updates/daily-news-analysis/spent-pot-lining. 

Thornton, Joe. "Environmental impacts of polyvinyl chloride (PVC) building materials." University of Oregon, Cambridge (2002). 

Harding, K. G., et al. "Environmental analysis of plastic production processes: comparing petroleum-based polypropylene and polyethylene with biologically-based poly-β-hydroxybutyric acid using life cycle analysis." Journal of biotechnology 130.1 (2007): 57-66. 

Sangwan, Kulip Singh, and Vikrant Bhakar. "Life cycle analysis of HDPE pipe manufacturing–a case study from an Indian industry." Procedia CIRP 61 (2017): 738-743. 

“Report.” Polyethylene The Worlds Most Used Polymer, sites.tufts.edu/frisbeemanufacturing/report/. 

Greenwood, Michael. “Toxins Found in Fracking Fluids and Wastewater, Study Shows.” YaleNews, 27 Sept. 2018, news.yale.edu/2016/01/06/toxins-found-fracking-fluids-and-wastewater-study-shows. 

Schipani, Vanessa. “The Facts on Fracking Chemical Disclosure.” FactCheck.org, 7 Apr. 2017, www.factcheck.org/2017/04/facts-fracking-chemical-disclosure/.