Hydroelectric Dams

Hydroelectric dams with large reservoirs can also be operated to provide peak generation at times of peak demand. Water is stored in the reservoir during periods of low demand and released through the plant when demand is higher. The net effect is the same as pumped storage, but without the pumping loss. Depending on the reservoir capacity the plant can provide daily, weekly, or seasonal load following. Many existing hydroelectric dams are fairly old (for example, the Hoover Dam was built in the 1930s), and their original design predated the newer intermittent power sources such as wind and solar by decades. A hydroelectric dam originally built to provide baseload power will have its generators sized according to the average flow of water into the reservoir. Uprating such a dam with additional generators increases its peak power output capacity, thereby increasing its capacity to operate as a virtual grid energy storage unit.

 The United States Bureau of Reclamation reports an investment cost of $69 per kilowatt capacity to uprate an existing dam,  compared to more than $400 per kilowatt for oil-fired peaking generators. While an uprated hydroelectric dam does not directly store excess energy from other generating units, it behaves equivalently by accumulating its own fuel – incoming river water – during periods of high output from other generating units. Functioning as a virtual grid storage unit in this way, the uprated dam is one of the most efficient forms of energy storage, because it has no pumping losses to fill its reservoir, only increased losses to evaporation and leakage.

A dam which impounds a large reservoir can store and release a correspondingly large amount of energy, by controlling river outflow and raising or lowering its reservoir level a few meters. Limitations do apply to dam operation, their releases are commonly subject to government regulated water rights to limit downstream effect on rivers. For example, there are grid situations where baseload thermal plants, nuclear or wind turbines are already producing excess power at night, dams are still required to release enough water to maintain adequate river levels, whether electricity is generated or not. Conversely there's a limit to peak capacity, which if excessive could cause a river to flood for a few hours each day.

Pumped Water

In 2008 world pumped storage generating capacity was 104 GW, while other sources claim 127 GW, which comprises the vast majority of all types of grid electric storage – all other types combined are some hundreds of MW.  In many places, pumped storage hydroelectricity is used to even out the daily generating load, by pumping water to a high storage reservoir during off-peak hours and weekends, using the excess base-load capacity from coal or nuclear sources. During peak hours, this water can be used for hydroelectric generation, often as a high value rapid-response reserve to cover transient peaks in demand. Pumped storage recovers about 70% to 85% of the energy consumed, and is currently the most cost effective form of mass power storage. The chief problem with pumped storage is that it usually requires two nearby reservoirs at considerably different heights, and often requires considerable capital expenditure.

Pumped water systems have high dispatchability, meaning they can come on-line very quickly, typically within 15 seconds, which makes these systems very efficient at soaking up variability in electrical demand from consumers. There is over 90 GW of pumped storage in operation around the world, which is about 3% of instantaneous global generation capacity. Pumped water storage systems, such as the Dinorwig storage system in Britain, hold five or six hours of generating capacity, and are used to smooth out demand variations. Another example is the 1836 MW Tianhuangping Pumped-Storage Hydro Plant in China, which has a reservoir capacity of eight million cubic meters (2.1 billion U.S. gallons or the volume of water over Niagara Falls in 25 minutes) with a vertical distance of 600 m (1970 feet).

 The reservoir can provide about 13 GW·h of stored gravitational potential energy (convertible to electricity at about 80% efficiency), or about 2% of China's daily electricity consumption. A new concept in pumped-storage is utilizing wind energy or solar power to pump water. Wind turbines or solar cells that direct drive water pumps for an energy storing wind or solar dam can make this a more efficient process but are limited. Such systems can only increase kinetic water volume during windy and daylight periods.

Rising sea levels are wreaking havoc on the Maldives

At an average of just 1.5m above sea level, the Maldives is the lowest lying country on the planet. Rising sea levels are now devastating its economy, one-third of which relies on tourism. The mere talk of a possible submersion had been denting investor confidence in recent years. By now, countless islands are being abandoned as the reality of global warming begins to bite.  A mass evacuation plan is underway, with many of the nation's citizens resettling in Sri Lanka, India and Australia.

Even small increases in sea level are likely to worsen existing environmental challenges on the islands, such as persistent flooding from waves often generated by storms far away. Sea level rise is also likely to place added stress on the Maldives' already scarce freshwater resources. Because of the low elevation of the Maldives, this island nation is especially at risk.

Warmer temperatures are causing sea level to rise for two reasons. The first reason has to do with warmer water temperatures. As water gets warmer, it takes up more space. With sea levels rising dramatically in the past few decades, the islands will suffer the most as they eventually become entirely submerged. Tuvalu could be uninhabitable by 2050, with some islands such as Kiribati being completely gone by 2100.

Aquaculture provides the majority of the world's seafood

Aquaculture – the cultivating of freshwater and saltwater fish under controlled conditions – has remained one of the fastest growing industries in the agricultural sector. Since the late 1980s, traditional "capture" fisheries have been on a plateau. Aquaculture, by contrast, increased by 8.8% per year from 1985 to 2010 and had witnessed an eightfold increase by the mid-2020s. It now accounts for the majority of the world's seafood, surpassing wild catch harvests by weight. The capture fishing industry itself has faced severe problems. Overfishing, climate change and pollution have all contributed to the sharp decline of yields. The largest centres for aquaculture remain in East and Southeast Asia – with the Philippines, Cambodia, Vietnam, Thailand and Indonesia seeing large increases in production.

Cambodia in particular has seen massive growth. New techniques have been adopted, helping to increase both sustainability and yield. One such method, used for the cultivation of jumbo shrimp, is super-intensive stacked raceways. Shrimp are grown in large, enclosed tubes called raceways, in which computers monitor and control a steady circulation of mineral water.  As they mature, they are moved down the stacked columns of tubes, until they reach the final bottom row, fully grown, where they are harvested. This method greatly increases the output of shrimp farms, up to one million pounds of shrimp per square acre, and can be deployed almost anywhere.

 The growth of aquaculture has caused a major shift in commerce and trade. Countries previously reliant on imports are now capable of producing vast quantities of fish, crustaceans, seaweed and other seafood Numerous start-up companies have appeared to fill the growing industry. Aquaculture as a whole will become one of the most vital industries in the world this century, as traditional commercial fishing breaks down and produces unsustainable yields.

New crystal allows divers to stay underwater for hours

Scientists at the University of Southern Denmark have developed a crystalline substance that can bind and store oxygen in high concentrations according to Mic. Apart from the possibility from breathing underwater, these crystals can also be used in lieu of oxygen tanks for people, industries, and even vehicles as a source of fuel. These crystals act as both a sensor and a container for oxygen molecules; they bind, store, and transport the oxygen within their structure.

The crystals function through their unique molecular and electronic structure. Cobalt is used in the material and the resulting molecular and electronic structure gives it an affinity to oxygen which allows it to be readily absorbed and bonded with the crystal. Christine McKenzie, researcher from the University of Southern Denmark describes it as  solid artificial hemoglobin. Approximately 10 litres of the crystals can absorb an entire room’s worth of oxygen. The oxygen can then be released by gently heating them or by introducing them to a low oxygen environment, and can be done so without the use of pumps or high-pressure equipment. 

These crystals can continually store and release oxygen without degrading. The rate which the crystals absorb oxygen depends on the oxygen content in the air, and the pressure and temperature of the environment they are in. Different types of crystals can be made to store and release oxygen at different rates and under different circumstances. New research is being done to see if light could also be used as a release mechanism.

Wastewater is an asset, not a liability

          Historically, wastewater treatment started as risk reduction for human health and welfare, migrated to environmental risk reduction, and has now matured into resource recovery and revenue generation. Technology and common practices are in place to treat water as a sustainable resource; we simply can no longer afford to use it once and "throw it in the ocean" nor can we afford the liability of not treating water to our best abilities to protect human health and the environment.

             Specifics, metrics, and detailed examples, not generalizations and platitudes, about recovery of the "water" from wastewater, profitably. It comes down to dollars and cents, a little math, and common sense, and usually much more the first than the last of those. Note: This is a live webinar delivered via WebEx. Session instructions will be emailed to you 24-48 hours prior to the webinar and the morning of the webinar. Webinars are live and interactive and students will have the ability to directly interact with and ask questions of the presenter.

              By 2020 I predict that a new class of distributed systems, powered by advances in our ability to use biotechnology to extract resources, such as energy, from waste, and the dropping cost of industrial automation, will begin to change our approach to managing water globally. Rather than a liability, wastewater will be viewed as an environmental resource, providing energy and clean water to communities and industry, and ushering in a truly sustainable and economical approach to managing our water resources.

Desalination: Easing the burden of thirst

              To sustain a growing population, research is bent on developing a solution to these issues. Ground water drilling and recycling of wastewater are examples of temporary solutions. Among these solutions is desalination. Desalination is the process of forcing salted water through a membrane by reverse osmosis, separating freshwater from impurities. An approach to reduce cost is substituting the primary material used in the constructing membrane with a relatively inexpensive material called polyamide. To avoid degeneration, the extraction of chlorine becomes an additional step in the desalination process. However, when chlorine is absent, microbes can occur and obstruct the flow of water.

             A possible solution is to replace polyamide with graphene oxide. The compound graphene has a structure similar to the honeycomb. It is predicted that this material will be more permeable to water and therefore reduce the pressure required to dictate the flow of water. Further research leans toward alternative materials like carbon nanotubes as the membrane. The underlying issue for integrating such findings is cost. The application of such processes must be considered on a global level.

               To counter such challenge, Jia Zhu of Nanjing University in China and colleagues worked on alternative sources of energy, such as the sun. Yet depending on direct contact alone from the sun is limiting. Research is looking into the use of absorbable materials to increase the amount of energy from sunlight. In short, the high energy consumption required for desalination often renders it a last resort. However, the growing urge to subsidize water scarcity on a global level leaves room for possible advancement and increasing innovation in the desalination process.

Japan's tidal energy system makes a splash

         In December 2010, Shinji Hiejima, associate professor of the Graduate School of Environmental and Life Science at Okayama University, Japan, developed a new type of tidal energy system, called the “Hydro-VENUS” or “Hydrokinetic-Vortex Energy Utilization System.” The Hydro-VENUS system will make energy available to coastal communities and communities with coastal neighbours who can potentially transfer the electricity to them. This energy will be environmentally friendly and there will be a constant supply since ocean currents are always moving. 

              The Hydro-VENUS works through a cylinder attached to a rod which is connected to a rotating shaft. The cylinder is held upright through buoyancy since it is hollow. As the ocean currents pass by the cylinder, a vortex is created at the back side of the cylinder, pulling and rotating the shaft. That rotational energy is transferred to a generator, creating electricity. When the cylinder is released from the currents, it becomes upright, returning to its original position, thus starting the cycle over.

                  The tidal system is different from a propeller-based system where the currents have to spin the propeller in order to create energy and requires a lot of force since the propeller is hard to turn. More energy can be created through the Hydro-VENUS system since less force is needed to move the cylinder pendulum.