Currently Browsing BLOG - Water Resources
New Bangalore Lakes Project Video
Check out the new video for the Sherwood Institute’s Bangalore Lakes Restoration Project! The full video can be viewed here.
The project page also has more information about the project’s background and ways that you can get involved to help.
Water Efficiency Series: Part 3- Water Scarcity, Awareness and Rainwater Harvesting
When looking at a map it appears that we have more than enough water to sustain all of the earth’s inhabitants with plenty of clean water. However, less than 1% of this water can meet human’s freshwater needs. (Source: Sherwood Institute Blog “All the Water in the World”, Aug. 25 2010). At present there are water wars in countries around the globe because of the scarcity of the valuable resource. Meanwhile, in many countries (such as the U.S.) we are over-using water without even thinking about it.
My best friend lives in St. Thomas. When I visited her last year, I was amazed that ALL of the water she used was rainwater from a rooftop catchment system. I was there for 10 days and in that time quickly adapted to “West Indian Showers” (turning on the water only for a few seconds at and the beginning and end of your showering process), using the absolute minimum amount of water for dishwashing, and learned the phrase “in this land of fun and sun, we don’t flush for number one!”
Although the island life takes a little getting used to, when I returned home I was SO conscious of just how much we, as a society, waste water. My roommate would defrost chicken by running cold water over it- for hours! Despite my complaints and explanations of why it was wasteful, she couldn’t understand that water is a precious resource.
Compared with other developed countries, the United States has some of the lowest water/wastewater costs as a percentage of household income. I know that when I became responsible for paying gas and electricity bills, our thermostat turned down and I became much more conscious of conserving energy. As a renter, I have still never had a water bill in my name, as is the same for most young people. Water seems free, and even for my landlord who is footing the bill; it is a very low cost utility.
At present, the cost of water does not reflect the value of the resource. Water infrastructure is aging and revenue generated from the sale of water is needed to improve water services. Increasing the price of water will not only generate revenue to improve the infrastructure but should also help to make the public understand that water is a valuable and precious resource.
In the United States, we are lucky to have infrastructure for delivering water conveniently and cheaply to our faucets. However, it takes a huge amount of energy to transport and treat water. Rainwater is an under-utilized resource that can be used as potable water without extensive pumping and treatment.
In many areas of the world, rainwater is used for everything: showering, drinking, dishwashing, irrigation and toilet flushing. However, in developed countries, which do have advanced water infrastructure, rainwater is generally used only for non-potable uses such as irrigation, toilet flushing, laundering, emergency water supplies, fire prevention use and process water uses.
Rainwater harvesting is a very scalable technology that can be as simple as catching rainwater from the roof and delivering it to storage tanks for irrigation or can be as complex as a large cistern with treatment processes for indoor use. It is important to match the rainwater use to the level of treatment provided. Water used for irrigation does not need to be treated to potable water standards, as that would be a waste of time, energy and money. However, if the water will be used indoors, it is important to insure that it is adequately treated to mitigate health concerns.
There are so many benefits of rainwater harvesting! These include (but are not limited to): minimizing stress on municipal systems (supports supply and reduces infrastructure maintenance costs); reducing energy required for treatment and pumping of centralized systems (thereby reducing greenhouse gas emissions); providing independent water security especially in times of natural disaster; often providing cost savings over time; decreasing municipal stormwater intake (thus reducing flooding, lessening quantity of stormwater needing treatment, and minimizing sewer overflow); and offering community benefits such as open green areas, public water awareness and self sufficiency.
Although using rainwater can be very beneficial, it is important that the catchment systems are designed well and with caution. Most concerns are related to health concerns from biological or chemical contamination. However, in good designs most of these worries are minimized. It is important that municipalities recognize the benefits of rainwater harvesting and create guidance to encourage safe catchment system design. Equally important is for citizens to use these regulations when building a system. Lastly, it is important that systems are inspected regularly to insure against contamination and to ensure that the water stays at a healthy pH level.
In conclusion, it is important to grow awareness in many developed countries about the scarcity of water. One way of doing this is by raising water prices to full-cost pricing. Once people become more conscious that we need to look at other water sources, hopefully rainwater harvesting will become more popular. Rainwater catchment systems are very scalable and have many benefits, but most be designed cautiously to ensure the rainwater remains safe. Hopefully, systems will become more prevalent to reduce the impact on current infrastructure and to ensure security to our water systems.
Water Efficiency Series: Part 2- Utilizing Graywater
Graywater, or “light graywater” is generally defined as water that has not been in contact with human waste and organics, water that has been used once in sinks, showers or washing machines. This differs from “dark” graywater, which includes water from kitchen sinks or dishwashers, and blackwater, which is wastewater from toilets.
It is estimated by the US EPA that the average household of four uses about 400 gallons of water per day. Approximately 70% of this is for indoor use and over 10% is usable graywater. As many states and countries are facing droughts more often, reusing graywater could prove to be a very beneficial strategy.
Graywater is most easily and commonly reused for irrigation purposes. The safest method is subsurface irrigation, where the water does not come in contact with humans and where amounts are generally not significant enough to infiltrate the drinking water supply. Whitewater (potable water that meets the EPA’s drinking water standards) should still be used for irrigation of food crops other than fruit and nut trees where the crop is far away from the ground. Subsurface irrigation ensures that the graywater will not pool on the surface or runoff, which could result in odors, mosquitoes, pollution, building damage and unsanitary conditions.
According to the U.S Geological Survey, about 1/3 of residential water use is used outside (mostly for landscape irrigation), which is about 7.8 billion gallons a day! (Source: U.S. EPA’s Water Efficiency Landscaping publication). This means there is a huge opportunity to recycle water for irrigation purposes.
Graywater systems for reuse generally consist of collection plumbing, treatment methods, disinfection and distribution components.
Dual plumbing is required in order to separate wastewater from graywater and blackwater sources. If graywater is used for subsurface irrigation, the system can be very simple, with just a three way manual valve installed that can cut off graywater to irrigation if an anticipated load is too heavily contaminated. Soil must also be tested prior to design to determine if a surge tank is needed to handle peak water loads. The surge tank is not a long term storage tank. Graywater should be treated or distributed immediately as the organic material in the water will cause it to become unusable and possibly harmful in as little as 24 hours.
For complex systems the next step is treatment. These scenarios include but are not limited to: graywater used for surface irrigation or indoor use, large collection sources, systems that store water and areas with stricter permitting regulations.
After a filtration pretreatment, treatment methods can include mulch basins, media filtration, filtration membranes, biological treatment and constructed wetlands. I highly recommend reading Sustainable Infrastructure: The Guide to Green Engineering and Design to learn more about each method as I could write an entire blog about each one!
After treatment, water should also be disinfected if it will be used indoors or aboveground. Water can be disinfected using ultraviolet irradiation or by adding chemicals such as chlorine, chlorine dioxide or iodine. Non-chemical methods are preferable, but also more expensive.
There are many ways to distribute graywater. In the simplest of systems, gravity carries water from the building to the lower-elevation landscape. Advanced systems generally require pumping in order to force water through treatment equipment. Water can be distributed through single or branch pipe systems directly to the landscape, to mulch basins, to small leachfields, through a perforated pipe to gravel filled trenches, to subsurface drip systems, or to subsoil infiltration galleys.
Graywater can be an excellent water resource; however, many factors contribute to ensuring a high-quality system. First of all, thorough planning and sound engineering are essential for a successful system. The soil conditions, climate, anticipated loads and end use are just a few of the many issues that must be analyzed during the design process.
After construction, the user must carefully maintain the system and be conscious of what is entering the system. Before doing research on graywater systems, I was very concerned about how soaps and detergents can be okay for plant life. I learned that although it is important to use environmentally-friendly products and be aware of what is going down the drain, generally the chemicals and salts introduced to plants and soils in small-scale graywater irrigation projects are usually too minimal to have any negative effects.
In fact, some of the articles I read stated that the nitrogen and phosphorous from soap and the potassium found in food actually nourishes plant life and recharges top soil. It is most important, however, to avoid soaps with sodium, chlorine, boron, borax, bleach and high levels of phosphates.
As policies allowing and promoting graywater use are beginning to increase, there are more and more government resources to read and learn all about graywater use. The EPA water recycling and reuse website, the Graywater Guidebook released by the State of California and Sustainable Infrastructure: The Guide to Green Engineering and Design are a few resources to start with. I hope graywater use will continue to expand and be more widely accepted as a water resource with the general public, as water recycling will help alleviate some of the stress on our current infrastructure. Water scarcity is an growing problem that will only increase in the years to come, we need to start implementing solutions now.
Water Efficiency Series: Part 1- LEED Concepts and Strategies
Recently I have been studying for the Leadership in Energy and Environmental Design (LEED) Green Associate exam. The LEED system has become a useful tool in the green building field.
It does not do the work of the design team, but rather sets goals and provides the framework for a green building project. I believe that it has also helped to advance the use of sustainable practices by providing a recognized benchmark, which has market value.
The LEED Green Building Rating System is a point system based on the following categories: sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality, innovation in design and regional priority.
There are 100 possible credit points in each of the first 5 categories. Innovation in design and regional priority credits allow for up to 10 bonus points. Based on how many points a project obtains, it will receive a certification, silver, gold or platinum status.
While studying I was particularly interested in the water efficiency category and decided to get a more detailed understanding of the LEED credits by re-reading the chapters on water conservation and supply and integrated water management in Sustainable Infrastructure: The Guide to Green Engineering and Design.
In this blog I write about the water efficiency credits for LEED certification, and in subsequent posts I will go into further detail about some of the strategies that LEED recommends.
The water efficiency category for LEED certification provides benchmarks to reduce water usage and provides suggestions to accomplish this, such as, using efficient plumbing fixtures, using graywater or captured rainwater for non-potable uses, applying xeriscape landscaping techniques and installing sub-metering devices.
The most environmentally and wallet friendly way to protect water resources is to simply reduce demand and conserve water. LEED addresses this by suggesting low-flow faucets, showerheads, and toilets, dual flush toilets and waterless urinals. The Bank of America headquarters in New York City, which achieved platinum certification in 2008, estimates saving 3.4 million gallons of water per year by using waterless urinals and 1.1 gallons per year with low-flow bathroom fixtures!
LEED also suggests decreasing water usage by using non-potable water. Non-potable water is water that does not meet drinking water standards set by the Environmental Protection Agency (EPA), but can be used for purposes that do not come into human contact. Sources of non-potable water include captured rainwater, stormwater, and graywater. Using non-potable water for irrigation purposes is the safest and easiest use, especially using sub-surface irrigation. However, it can also be used indoors for toilet flushing and process water (cooling towers, boilers, chillers and commercial kitchen use).
In addition to using non-potable water for irrigation applications, we can minimize water usage for landscaping by choosing native plants and applying xeriscaping. Xeriscaping is a type of landscaping which emphasizes minimal water use, soil improvements, mulching and efficient irrigation. Designers should also use efficient irrigation equipment; for example: sprinkler systems are only 65% efficient while drip systems are 90% efficient.
Lastly, LEED suggests installing sub-metering devices for indoor, outdoor and process uses. Sub-metering is useful for monitoring water use, identifying leaks or problems, and tracking peak periods of water use. Most sub-metering devices track cold, potable water use.
Strategies such as “use low-flow plumbing fixtures” or “install sub-metering” are relatively self-explanatory and do not require much design engineering. However, utilizing graywater, harvesting rainwater and treating wastewater can be much more intensive strategies. To understand these techniques, I turned to Sustainable Infrastructure: The Guide to Green Engineering and Design. In upcoming posts I will describe these methods in more detail.
World Water Day 2011
The United Nations General Assembly declared the first World Water Day as March 22, 1993. Eighteen years later March 22 still serves as a day to focus the world’s attention on the under availability of freshwater and the importance of sustainable water management.
Each year a new topic is presented for the world to spotlight. In the past these topics have included women and water in 1995, groundwater in 1998, water and disasters in 2004, water and culture in 2006, water scarcity in 2007, and water quality in 2010. This year the theme is “Water for Cities, Responding to the Urban Challenge.”
Currently, 3.3 billion people live in cities. That number grows by two people every second. This accounts for half of the world’s population. 93% of this urbanization occurs in poor, developing countries. People in underdeveloped urban areas have the least access to freshwater and also pay the highest costs for “clean” water.
Utility companies in urban areas are becoming less able to sustain themselves. It is becoming impossible to extend sewers to slums and current piping infrastructure is already unable to handle waste loads in many areas.
It is for this reason that all infrastructure projects must begin using sustainable designs, especially water and wastewater projects. These measures should include rainwater harvesting, low impact development stormwater design, sustainable blackwater management, and water recycling, reuse, and conservation.
There are five key messages that need promotion regarding urbanization and water services.
- The impact of urbanization on the water sector: as the world’s population grows, especially in informal cities, providing water and wastewater services will become increasingly important.
- The impact of sanitation, pollution and industrialization on the environment needs to be recognized. Two of the UN Millennium Development Goals are “halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation” and “by 2020, to have achieved a significant improvement in the lives of at least 100 million slum dwellers.” Utilities and local governments need to push to meet these goals and explore opportunities to reuse urban waste in a way that can have social, economic and environmental benefits.
- World Water Day 2011 is focusing on the importance of non-corrupt, committed government and utility management. Strengthening local governments and improving regulation, professionalism and accountability to customers is vital in advancing water and wastewater services, especially in underdeveloped countries.
- Many counties can simply not afford to keep up with the implementation of new and sustainable infrastructure. New investment opportunities need to be explored, including tariffs, taxes and transfers.
- It needs to be understood that water availability depends on natural resources and in the future these resources are threatened by extreme weather events and a changing climate. It is becoming increasingly important to adapt infrastructure to climate change, to protect the environment when designing new networks and to reuse water to improve quality and quantity.
The growing population in cities creates huge opportunities! Cities are the hub of employment and wealth, as well as creative thinking. This means that hope for development of water and sewage services are greater in urban areas than rural areas which are more spread out and generate less income.
Hopefully, World Water Day 2011 will serve to expand the knowledge about the growing problem of water and urbanization, facilitate policy dialogue and promote discussion about innovative solutions to water and wastewater management issues.
The main event for World Water Day 2011 is being held in Cape Town, South Africa. However, there are SO many events being hosted all around the world. The official World Water Day website has a map and events lists to find and join in on events in your area.
The World Water Day 2011 official website has a huge amount of information on the event and links to materials and reading about water and urbanization. I encourage everyone to take a look and explore online a bit.
Renewable Energy: Water Power; Part 3 of 3
This is the final segment on five types of hydrokinetic technologies, all mentioned in Sustainable Infrastructure: The Guide to Green Engineering and Design by S. Bry Sarté. These systems are microhydroelectric, wave energy, vortex-induced vibration (VIV), tidal power and ocean thermal energy conversion (OTEC). My final blog on the topic will discuss OTEC power: how it works, different types of systems, and its many different applications.
Ocean Thermal Energy Conversion (OTEC):
OTEC uses the differences in temperature between cold, deep ocean water and warm, shallow water to power a heat engine capable of producing electricity. OTEC is most efficient when there is a large temperature difference (approximately 36 degrees Fahrenheit), thus the best potential sites are tropical areas. OTEC systems are closed-cycle, open-cycle or a hybrid of the two.
Closed-cycle systems pump warm ocean water through a heat exchanger where it is used to heat a working fluid with a low boiling point (such as ammonia). The working fluid is vaporized and the expanding vapor turns a turbo-generator. Cold seawater is then pumped through a second heat exchanged to condense the vapor back into a liquid.
Open-cycle systems use the warm seawater directly instead of a secondary fluid. A low-pressure container causes the water to boil, and like in the closed system, the expanding vapor drives a turbine which, in turn, powers an electrical generator. This is also a desalination process, as the steam is fresh water. The steam is condensed back to liquid form by exposure to the cold ocean water.
Hybrid systems evaporate warm seawater in a vacuum, similar to in the open-cycle systems. However, this steam vaporizes a working fluid, similar to a closed system. Again, the expanding vapor fuels a turbine to produce electricity and the cold ocean water is used to condense the vapor back into a liquid.
Sites can be located on or near land, on continental shelves or as floating facilities. Each has its advantages and disadvantages mainly related to the difficulty and cost of installation and maintenance and the safety of the facility in turbulent conditions.
OTEC is primarily thought of as a source of renewable energy; however, it has several useful byproducts and uses.
First, as mentioned above, desalinated water is produced in open or hybrid cycles. A 2MW plant could be capable of producing approximately 150,000 cubic feet of desalinated water per day!
Secondly, the cold seawater needed for an OTEC system can also be used in chilled water coils to provide air conditioning. The InterContinental Bora Bora Resort and Thalasso Spa is the first hotel in the world to use seawater air conditioning for all of it’s cooling needs.
Deep ocean water is some of the most nutrient rich water in the world. For this reason OTEC systems support mariculture, which is the farming of aquatic organisms. Salmon, lobster, trout, oysters, clams, and spirulina are just some of the species that can be raised in pools supplied by OTEC pumped water.
The cold ocean water can also be used in land-based agriculture, by running the water through underground pipes and chilling the soil. This allows plants to be grown in non-native climates.
OTEC is a promising technology; however, there are still economic, political and environmental concerns. Hopefully, careful site selection can minimize negative impacts.
All of the water sources of renewable energy are capable of producing huge amounts of energy. Hopefully in the near future, these technologies will be further optimized so that they can be implemented in more locations with lower costs and environmental impacts than fossil fuel electricity generation. Water power might well become the “wave of the future” for renewable energy.
Renewable Energy: Water Power; Part 2 of 3
This post is the continuation of my previous blog on water power. In that segment I summarized tidal and wave energy technology. I had planned on discussing microhydroelectric installations, Vortex Hydro Energy, and ocean thermal energy conversion (OTEC) in this section, however because there is SO much important information I have decided to again separate the post into another part. This piece will focus on microhydroelectric power and the Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) system which both utilize flowing water to generate electricity.
Microhydroelectric power is very similar to hydroelectric power but it is adaptable for small-scale installations such as single homes or small communities. Microhydro generally only produces up to 100kW of power and is much more sustainable than big, traditional hydroelectric power installations. And even more appealing is the fact that microhydro does not require rivers to be completely dammed. This is very beneficial because dams interrupt the water cycle, travel of fish and animals, and the flow of nutrient rich sediment downstream.
Microhydroelectric power is generated using the energy from flowing water. First an intake tank filters the water to ensure no debris or fish enter the system. The water then flows through a pipe (called the penstock) to a controlling valve that regulates the flow and speed of a turbine. The turbine turns a shaft that is used to power a generator, which converts the flow and pressure of the water to electricity!
This energy can then be stored in batteries and distributed to the power system. At the end of the process, the water used in the system is returned to the river or stream along a tailrace channel.
The image below is from a PowerPoint presentation used in a course I took at the University of Vermont called “Sustainable Development of Small Island States: St. Lucia.” I had the opportunity to see first hand how well the microhydro system worked for the owner of the land, Mr. Sly Joseph. Mr. Joseph powered his whole home and an outdoor classroom using the power generated at the La Tille Waterfall on his property. The local schools teach classes on his property to spread the message about how well microhydro power works, especially on small islands where traditional electricity is very expensive and not readily available.
Vortex-Induced-Vibration (VIV)/ Vortex Hydro Energy:
VIVACE (Vortex Induced Vibrations Aquatic Clean Energy) is an emerging technology that extracts energy from flowing water currents and utilizes the science of vortex-induced vibrations. Most of the research I could find on the technology was quite confusing, primarily because the science explaining VIV is quite complex. However, using VIVACE technology is actually quite simple. http://www.vortexhydroenergy.com is a great site that explains the system very well.
VIVACE is the only water power technology that I will discuss that does not use any turbines, and because the cylinder oscillations are only about one cycle/second there is not direct threat to aquatic life passing through.
Boxes with cylinders are installed on a riverbed or suspended under the surface of the water, as the water flows through the cylinders the movement causes the cylinders to move up and down. The cylinder is attached to a magnet that also slides vertically, creating a DC current. The DC current is then converted to AC current.
The phenomenon behind how the cylinders of the VIVACE system move perpendicular to the current direction is the same as how fish move through the water. Very basically, vortices are produced and discarded on the downstream side of round objects in a fluid current. The vortex shedding oscillates between the bottom and top of the object, thus creating an alternating lift on the body.
The company responsible for the design, Vortex Hydro Energy LLC, predicts that an array of cylinders about 2 stories high could power about 100,000 homes. The technology can be used to power desalination plants, use energy from rivers without dams and provide power in coastal areas.
I love the microhydroelectric and VIVACE technologies. Both are very simple systems that have small-scale potential (unlike wave, tidal and OTEC power which can only be installed for large-scale energy production). Both systems can be installed on a small river and, without changing the site very much, can utilize the energy in flowing water to provide electricity for a home nearby or a community. Hopefully these systems will be implemented more to reduce our dependence on fossil fuels and on traditional hydroelectric power which dramatically alters the environment.
Beijing Golf Course Water Conservation Needs and Strategies
Since the opening of China’s first golf course in Guangdong Province in 1984, the country has seen a boom in the sport, which is a symbol to many Chinese of luxury, upper class lifestyle, and one of the pinnacles of western recreational status. In China, golf is something that only the very wealthy can afford, with club fees ranging from “cheap” at a couple thousand dollars per year to tens of thousands of dollars per year for the very exclusive courses, meaning that only approximately one in every 100,000 Chinese people could ever afford to play 18 holes in China. Despite the small number of potential Chinese golfers however, the symbol and status of golf in China has created a reasonable market for the development of golf courses.
Such development comes with significant environmental challenges. Most golf courses are constructed in the suburban areas of large metropolitan cities, which, especially in northern China are already strained for water resources. Golf course construction has several implications. Because the water required to maintain greens, tee boxes and fairways is significantly more than that of land covered by trees and bushes, strains are created on both groundwater and municipal water supply. The deforestation of areas to build 18-hole courses also increases soil evaporation, decreases infiltration, increases stormwater runoff and decreases the water-holding capacity of the soil. Also, since many suburban golf-courses are located on lands once used for agriculture, it is common practice to directly extract groundwater from agricultural wells already built on the land for irrigation purposes, which leads to the lowering of the groundwater table in areas which are already experiencing subsidence on a regional scale.
The municipal government of Beijing has of course, realized that this problem could be very severe. This year, in fact, Beijing experienced its driest winter to date, with 108 days straight with no precipitation. There have been several policies passed attempting to curtail water-intensive industries. In 2005, the Beijing Water Authority passed its first announcement on golf course water management, called the “Announcement on the strengthening of golf course water use management”. Within this document, it was specified that the 40 golf courses within Beijing’s 11 districts would have to pay doubled or tripled prices for water usage exceeded a set maximum. The announcement also stated that golf courses were required to utilized reclaimed wastewater for both waterscaping and irrigational purposes and that they should also maximize harvest of rainwater.
In 2006, another announcement was sent to all registered in Beijing, requiring golf courses to register usage of on-site wells, increase permeable areas (such as paths, parking lots, etc) on the site, maintain irrigation equipment, and for golf courses within the distribution network of reclaimed wastewater to utilize this as a source for irrigation, and flushing toilets.
In 2010, the opening of new water-consuming enterprises—including new ski slopes, golf courses, and bathhouses—in Beijing was banned.
While these policies were definitely a step in the right direction, several articles question their efficacy and the extent to which the policies are actually enforced. In March 2010, Probe International published a report which stated that “fewer than 7 percent of Beijing’s golf courses use reclaimed water for irrigation despite municipal guidelines that strongly suggest they do”. On February 11 of this year, the Economist published an article stating that according to aerial photographs, there are 170 confirmed golfing establishments in Beijing, including driving ranges. Previous estimates of the number of golf courses vary because some places avoid calling themselves “golf courses” in order to have more leniencies in management. The official Xinhua News Agency reports 38 golf courses as of 2010
Although there are definitely some questionable aspects of the efficacy of legislation and the commitment various players have in their implementation, there is no doubt that golf courses in Beijing must adopt water reuse and saving measures. There are three main strategies that are important in golf course water management.
The first is to increase the amount of reclaimed wastewater that is being used for irrigation and waterscaping. As of August 2010, only 4 of the 38 official golf courses were utilizing reclaimed wastewater for irrigation. Interestingly, in the same month, it was also reported in Chinese media that the demand for reclaimed wastewater in Beijing far exceeded its supply. In many developed countries, technology is good enough that up to 70% of all wastewater can be reused as reclaimed wastewater after treatment. In Beijing, only about 10% of wastewater is being reutilized, so the potential for reclaimed wastewater to be a major water resource in the future is very large. Because in some cases, wastewater treatment plant effluent may not meet standards for irrigation or waterscaping uses (especially if nutrient levels are high), golf courses may consider the use of constructed wetlands to raise the quality of the water. This strategy may even allow for golf courses outside the reach of the current reclaimed wastewater distribution network to carry out additional treatment of treatment plant effluent to raise the quality of the water independently.
The second strategy that will be important for golf courses in Beijing to adopt is drainage and rainwater harvest design. Because grass lawns experience greater runoff than forested areas, specific attention needs to be considered in the grading of the landscape with respect to maximizing infiltration into the underlying aquifers and in minimizing waste during irrigation. Expert engineers should be consulted for questions relating to soil type, infiltration speed, soil water capacity, and grading.
Lastly, the selection of drought-resistant plant species should also be considered in golf course design. Already in Beijing it is reported that drought resistant grass is already being used for fairways and roughs, which typically account for over 60% of the total area of the course.
Research is being done on golf industry development at the Turfgrass Institute of Beijing Forestry University.
Renewable Energy: Water Power; Part 1 of 2
The ocean has always intrigued me. Growing up I got hooked on sailing and fell in love with its beauty. I also developed a healthy respect for its power. I clearly remember a high school presentation about wave and tidal power. I was so intrigued about how energy could be harnessed from water and used as a source for renewable energy.
Sustainable Infrastructure: The Guide to Green Engineering and Design by S. Bry Sarté mentions five types of hydrokinetic technologies: microhydroelectric, wave energy, vortex-induced vibration (VIV), tidal power and ocean thermal energy conversion (OTEC). The Sherwood Institute focuses on the water-energy nexus, and although much of its work focuses on the balance of water and energy efficiency, I thought energy generation using water an appropriate topic to discuss.
In this first blog, I will summarize research on wave energy and tidal power. In part two, I will discuss other popular types of water power.
Energy from the ocean can be generated using a variety of technologies that capture energy from surface waves or pressure fluctuations below the surface. The devices are all installed at or near the water’s surface; however, they can be located nearshore, offshore or far offshore.
There are many devices being developed to harness this power. I’ve focused on four primary technologies: point absorbers, overtopping devices, attenuators and terminator devices.
- Point absorbers use the relative motion created by waves of a floating buoy to a fixed structure to power electromechanical or hydraulic energy converters.
- Overtopping devices consist of a reservoir and turbine system. Incoming waves fill the reservoir, making the water height in the reservoir higher than that of the surrounding ocean. When the water is released, the energy of the falling water drives a turbine or other conversion device to create electricity.
- Attenuators are floating structures that are situated in the same direction as wave travel. The multi-segment device flexes as waves pass. This flexing drives hydraulic pumps and converters.
- Terminator devices are generally designed to be near shore. They are oriented perpendicular to the wave direction. One form of terminator device is the oscillating water column, which allows water to enter the bottom of a column filled with air. Passing waves cause the water column to move up and down. The forced-out air powers a turbine to convert the energy to electricity.
The prospect of harnessing wave energy is very promising. However, there are environmental considerations: visual appearance and operation noise above and below the surface, marine habitat changes, accidental release of hydraulic fluids, sharing sea space with recreational and commercial boaters, and possible reduction in wave height and site change while installing or decommissioning devices. Many of these concerns can be addressed with careful site selection and monitoring; however, they are matters that must be addressed.
If you are interested in learning more about wave energy research, I suggest reading Technology White Paper on Wave Energy Potential on the U.S Outer Continental Shelf.
Ocean Tidal Power:
Tidal power harnesses energy from the changing tide. In some areas, the gravitational pull of the sun and moon and the rotation of earth can cause up to a 40-foot water height differential between high and low tide. Most of the technology for harnessing tidal power uses submerged turbines similar to wind turbines. There are three well developed methods for capturing this energy: barrages, fences and turbines.
- Tidal barrages are dams across an inlet with gates that allow water to flow into the area and then empty during the ebb tide. As the water flows in and out of this “tank”, the water flows through turbines which activate electric generators.
- Tidal fences are generally used in channels between two landmasses. Vertical axis turbines are mounted on a fence. As water flows past these turbines, the current causes the turbines to spin. The turbine action, again, drives electric generators to produce electricity.
- Tidal turbines can be located anywhere where there is a strong tide. The turbines are arrayed in rows, similar to wind turbines on a wind farm, only underwater. The current of the ebbing and flowing tide cause the turbines to turn and produce electricity in the same fashion as the two previous technologies.
Water is about 800 times denser than air. Therefore, turbines located underwater have enormous energy potential. However, there are a lot of environmental concerns, including: sea-life migration, navigational and recreational disadvantages, and changing the ecosystem in barraged areas where silt buildup can occur. Tidal turbines might prove to have the least environmental impact because they do not block the natural flow of water like the other two methods.
I believe wave and tidal energy hold enormous potential! The ocean is so powerful, and both forms of renewable energy generation could produce an incredible amount of electricity. However, there are cost and environmental concerns that still need to be addressed – and utilizing these technologies are only possible on a large scale and in very specific site locations. These forms of power are still being intensely researched, so, hopefully, new technologies will minimize environmental impact and maximize the amount of electricity that can be generated so that more sites can be used to produce these types of power.
In my next post, I will continue the water power discussion by addressing micro-hydroelectric, ocean thermal energy conversion and vortex-induced vibration power.
Sustainable Solutions for Hot Water Production and Water Conservation
As I have previously mentioned, I live in Lake Tahoe, CA. Although it has been abnormally warm this year (60 degree spring-skiing days in January!), the water in our house runs SO cold for SO long! Since we keep the house at a pretty chilly temperature, this icy water makes for a very unpleasant hand washing experience.
Despite doing things like brushing my teeth and letting the water drip for the cat (my crazy Bengal refuses to drink anything but water from my own drinking glass or a running faucet!) BEFORE washing my hands, the water still needs to run for far too long to get warm. Or I have to suffer and have freezing cold hands! I have also heard many people complain about how cold the water is in the public bathrooms at the ski resort.
People in cold ski towns don’t like cold water. So, I decided to learn more about sustainable ways to heat water and reduce the use of un-used, cold water.
A few facts about unused water waste:
-Running the water for a few minutes, even with low-flow fixtures, wastes approximately 3-5 gallons of water. For a family of four, that is about 15,000 gallons of water a year.
-If someone drinks the recommended 8 cups of water a day, that is only 185 gallons of water needed per year. Meaning, just by running water, waiting for hot water, you could be wasting about 20 times the amount of water you drink per year.
-Running hot water is a huge energy drain! Running your faucet with hot water for 5 minutes is equal to the energy usage of a 60-watt light bulb for 14 hours!
The good news is, there are many ways to maximize water and energy efficiency for hot water. These include using low-flow water fixtures, insulating hot water tanks and piping, planning hot-water tank placement to minimize piping, using EnergyStar and WaterSense rated appliances, and being conscious of water usage when taking showers, brushing teeth, washing dishes and laundry, etc.
In addition to all of these improvements, there are a lot of choices to make when deciding what the best type of hot water heater to use (tankless, on-demand, re-circulating systems, solar-hot water… the list goes on). For this blog I am going to focus on residential hot water, highlighting one system for energy efficiency and another system for water efficiency.
One of the most sustainable methods for heating water is solar thermal (heating water using solar radiation). This is discussed in Sustainable Infrastructure: a Guide to Green Engineering by S. Bry Sarté. This heated water can be used for residential hot water, hydronic radiant floor-heating systems, heating swimming pools, and even commercial electricity generation. A typical solar hot water system can provide enough hot water for the average home.
Solar thermal collectors are generally black coils filled with water, which are installed on the roof. The water heats up in the sun and then is stored in a tank until needed. Systems are almost always constructed with an auxiliary water heating system that is activated if the water drops below a set temperature so that hot water is always available. Solar thermal hot water generation is a relatively cheap system, much less expensive then solar photovoltaic panels used for residential electricity generation, so they can be a nice place to start when greening your home.
Solar thermal systems can be passive or active. Passive systems use convection to naturally move the warmer liquid (water or a antifreeze heat transfer fluid) to the storage tank and cold water to the collectors for heating. These systems are simpler and less costly than active systems but can only be used in moderate, sunny climates.
Active systems use pumps to move water from the collectors to storage tanks. This allows the tank to be situated under the collectors, which can increase efficiency since it can be stored indoors in a more insolated space. A controller is also used to ensure that water is only being pumped when the water in the collector is warmer than in the tank. In addition to increased efficiency, active systems have less risk of overheating and freezing because of the tank location and the use of a controller.
Because I am concerned with just how much water I have been wasting while waiting for hot water, the water efficiency technology I was most intrigued by is the hot water demand/cold water return system. This system works by returning cold water to the heat source, instead of letting it drain, becoming waste water. I found that the Chilipepper pump website had some of the best explanations on how the method works, so I encourage you to learn more by checking it out.
Basically, when you go to the sink you turn on a pump that begins drawing hot water from your water heater (these work with any type of heating/storage system). Water going through the pump is returned to the water heater until the pump sensor detects water temperatures above a set temperature. At this point the pump will turn off and allow the hot water to flow to the faucet.
These pumps also draw water faster than most fixtures, especially new low-flow faucets and showerheads. This means that the outlet will receive hot water much more quickly than without the pump. Also, since the water isn’t being wasted while waiting for it to heat up, you don’t need to be concerned about the high flow rates.
There are so many other ways to save water and improve energy efficiency with hot water. This blog would be way too long if I explained them all! I encourage everyone to research the topic more. Point of use water heaters or a tankless heater might be a good way to green your hot water heating system. The EPA also has a great program called WaterSense, and I encourage you to look at their website; it is filled with suggestions on how to reduce water-waste. Limiting hot water use, using sustainable methods to heat water and not wasting unused water all help to make a home environmentally friendly. I hope the methods mentioned above are helpful and jump-start your thinking about hot water usage!
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