Smart Renewable Energy Microgrid

Smart Renewable Energy Microgrid

A small team of enthusiastic and adventurous engineers at FluxGen Engineering technologies has come up with a solution to electrify houses in remote rural areas  that are not directly connected to the electricity board power grid. Read on to know more.

Microgrid is basically a small-scale power supply network that is designed to provide power for a small community. It can-not be used for high-power consuming devices but can be used as an alternative approach to integrate small-scale distributed energy resources into low-voltage electricity systems. Enabling local power generation, it comprises various small power generating sources that make it highly fexible and efficient.

Basically, the solution aims to electrify houses that are not directly connected to the electricity board power grid due to their remoteness. To be precise, “We have integrated existing hardware components in the market with a powerful embedded system. The setup forms an electricity grid that is small enough to be called a microgrid. This system is powered by renewable energy sources such as solar photovoltaics (PV), wind and micro-hydel. It can be remotely monitored from anywhere in the world,” explains Ganesh Shankar, managing director, FluxGen Engineering Technologies.

Fig. 1 shows the model of the smart renewable energy microgrid.

Fig. 1: Models of houses which form part of the smart microgrid setup at FluxGen Lab

From concept to product
“Over 400 million Indians either do not have access to electricity or have intermittent access to electricity. Connecting the whole country to the main electricity grid is a task that would take several years and in some places it may not make an economic case,” points out Hari D.K., chief engineer, FluxGen Engineering Technologies. Distributed energy generation and distribution can potentially solve this problem.

An off-the-grid renewable energy plant connected to a network of houses in rural areas will potentially provide them the same quality of power as obtained from the main electricity grid.

“In India, electricity grid penetration is very poor. Fortunately, the communication network penetration in India is much higher. This makes the case for a smart microgrid whose performance can be remotely monitored and virtually supervised,” says Shankar.

Fig. 2: National Instruments’ Single Board RIO (sbRIO 9641) used to intelligently control and monitor the smart microgrid

“We are planning to put our systems in places where there is no electricity. But in case the grid does penetrate, the microgrid should ideally be compatible with the grid for the following reasons:

1. It could optimally utilise grid power and renewable energy power, ensuring that the customers get electricity most of the time.
2. If power generated from the renewable energy source is in excess, it should be able to feed it back to the grid so that other microgrids connected to the network could utilise it,” he said.

Regarding the time taken in developing their concept to product, Shankar says, “Before starting Flux-Gen I was working with GE. There I happened to work on building smart energy meters for about six months. During that time, I got a good understanding of smart grid. After quitting GE, I worked with Selco Solar, a rural electrification company, for about five months. So when I started FluxGen, I wanted to club my experience of working on smart grid to rural electrification so that rural dwellers could have a standard of living as good as an urban dweller’s. Then I decided to pursue the microgrid as I could see the value in it. The whole process duration from inception to working prototype can be estimated as three years.”

Fig. 3: Solar panels on roof tops of the houses will be the primary power source to the microgrid

What makes it different

Microgrid is an idea that has been in the picture for quite some time now. Talking about how their solution differs from the microgrids existing in India, Hari reveals, “There are several microgrids set up in India, but most of them are based on DC transmission. We have developed an AC microgrid system.”

Giving rural houses AC instead of DC will allow them to avail all the facilities an urban dweller could get. Ganesh explains, “Electrical wiring done in the microgrid is similar to that of the main grid, except that it will be connected to lot lesser number of houses. Hence consumers of power from the microgrid will be able to run any electrical appliance that they have.”

Ganesh adds, “While they wouldn’t have much limitation on instantaneous power consumption, the total energy they can get from such a microgrid could be limited based on the size of the plant as the total size of the plant will be limited by the number of solar panels and other energy sources, unlike the main grid which, technically, can give you any amount of electricity you are willing to buy.”

Standard solar energy systems are available as autonomous systems that are connected to a single house. However, there is an inherent advantage in pooling (like car-pooling) that is leveraged by a microgrid to deliver electricity to several houses.

“For example, one of the components of a solar PV system is the inverter, which converts power from DC to AC. Suppose an inverter of 1kVA size (rating) costs Rs X. Then, a 10kVA inverter for a pooled system would not cost 10X but closer to 3X. Also, 1kVA inverters would have power conversion efficiency of about 80 per cent, whereas a 10kVA inverter would have an efficiency of 95-98 per cent,” explains Shankar. Thus there are cost and quality advantages to having a microgrid solution over independent systems (refer Fig. 2).

How it works

Ganesh and Hari explain the working by referring to Fig. 1. Basically, the entire system or solution consists of energy consumers (individual houses) and an energy generation setup. Individual houses are connected to the power network via a smart meter, which can communicate with the generation end. One of the main components used in this solution is the solar PV panel. It is placed on the rooftop of every house. Another vital component is the solar converter, which performs three tasks. It charges the battery from solar power, converts the DC power from solar or battery to AC, and if the microgrid is connected to electricity board (may be in the near future), then feeds the excess power to the main grid.

Why DC microgrid is less effective than AC microgrid

1. Household appliances like bulbs, fans and television sets are commonly available with AC power as the input, whereas getting the same in DC format is difficult. If one is still able to get a DC system, it will cost more than the AC system. 2. Also, AC products are more evolved, as they are manufactured by leading electronics companies. Though AC power is converted to DC in most systems, opening up a system just to trace the DC point is not feasible. DC utilities are not scalable in the Indian market. 3. Power dissipation (resistive loss) in AC wiring is much lesser than in DC wiring. For houses in the vicinity (in a DC microgrid), this could lead to reduced overall system efficiency. In our case study, we could do a calculation for both the systems and get the exact figures. 4. The efficiency of inverters increases with power capacity, while the cost reduces. For instance, one can get an inverter with 6kW power capacity and an efficiency of more than 90-95 per cent at three times the price of a 1kW inverter, which will have an efficiency of about 85 per cent. For a microgrid with more than ten houses, the peak power required would be about 6 kW. If those ten houses are powered with DC power, the cost and efficiency would perhaps converge with AC power. 5. Also, during some emergency or maintenance, a diesel generator set (an AC power source) can be connected to the system in order to ensure that the consumer is not deprived of power. —

The battery incorporated in this so-lution stores the solar energy to power the house when there is no sunlight. The feature of Energy and Health Monitoring system monitors the plant operation and ensures the plant is operating in the limit of safety and gives an alarm if it is not in a safe health condition. This feature enables preventive maintenance of the plant. The most important aspect of this solution would be to tabulate the energy consumed by each individual house and also communicate the energy and health data to the remote location via Internet. For this there is a communication module that communicates with the individual meters. This helps the plant operator to virtually monitor the performance and health and also control the plant with an internet connection, while being located anywhere in the globe.

Fig. 4: Digital meter used for energy monitoring and communication at individual houses

The smart meter can measure the electrical parameters and can also connect or disconnect power according to the operator’s instructions, and it can communicate with the communication module continuously. So the power and meter communication network forms the channel for power transfer from the generating point to individual houses. The communication network could be wired or wireless based on the geographic spread.

In the future
Depending upon the geographical location of various other renewable energy sources such as wind, micro-hydel or biogas, this system can be integrated with solar as the primary source.

“If in case the electricity board extends the grid, then it can be fitted to the microgrid seamlessly. Diesel generator can also be integrated as a contingency plan (for power when there is emergency or during maintenance),” says Hari.

Ganesh informs, “The first version is ready. Based on the feedback we get from the initial takers, we will implement more features. A fully functional working prototype is ready in our lab and we are looking forward to work with government bodies, NGOs, international bodies, private setups and social enterprises in building as many smart renewable energy microgrids as possible.”

Adding to that, Hari says, “We wish to sell the smart renewable energy microgrid tools to government, NGO or private setups who will operate the system using the tools we have developed for the operation of a microgrid. We will also sell them billing software, which will help them to collect appropriate charges from the individual power consumers of the microgrid.”

World's thinnest substance graphene 'will power the next generation of computers'

World's thinnest substance graphene 'will power the next generation of computers'

 


Today, most information is transmitted by light – for example in optical fibrers. Computer chips, however, work electronically. Somewhere between the optical data highway and the electronic chips, photons have to be converted into electrons using light-detectors. Scientists at the Vienna University of Technology have now managed to combine a graphene photodetector with a standard silicon chip. It can transform light of all important frequencies used in telecommunications into electrical signals. The scientific results have now been published in the journal “Nature Photonics.”




Computing power made of carbon?

Both academia and the industry have high hopes for graphene. The material, which consists of a single layer of hexagonally arranged carbon atoms, has extraordinary properties. Two years ago, the team around Thomas Müller (Institute of Photonics, Vienna University of Technology) demonstrated that graphene is ideally suited to turn light into electrical current. “There are many materials that can transform light into electrical signals, but graphene allows for a particularly fast conversion,” says Thomas Müller. So wherever large amounts of data are to be transmitted in a short period of time, graphene will in the future probably be the material of choice.

Graphene – a two dimensional 

sheet made of carbon atoms – can convert light into electrical current.

The researchers had to come a long way from the basic proof of what the material can do to actually using it in a chip – now they have succeeded. The Viennese team worked together with researchers from the Johannes Kepler University in Linz.

“A narrow waveguide with a diameter of about 200 by 500 nanometers carries the optical signal to the graphene layer. There, the light is converted into an electrical signal, which can then be processed in the chip,” Thomas Müller explains.

THE WONDER OF GRAPHENE

Graphene is a single atomic layer of carbon atoms bound in a hexagonal network.

It not only promises to revolutionise semiconductor, sensor, and display technology, but could also lead to breakthroughs in fundamental quantum physics research.

It is often depicted as an atomic-scale chicken wire made of carbon atoms and their bonds.

Scientists believe it could one day be used to make transparent conducting materials, biomedical sensors and even extremely light, yet strong, aircraft of the future.

Similar to another important nanomaterial - carbon nanotubes - graphene is incredibly strong - around 200 times stronger than structural steel.

Versatile and compact

There have already been attempts to integrate photodetectors made of other materials (such as Germanium) directly into a chip. However, these materials can only process light of a specific wavelength range. The researchers were able to show that graphene can convert all wavelengths which are used in telecommunications equally well.

The graphene photodetector is not only extremely fast, it can also be built in a particularly compact way. 20,000 detectors can fit onto a single chip with a surface area of one square centimeter. Theoretically, the chip could be supplied with data via 20,000 different information channels.

More speed, less energy




“These technologies are not only important for transmitting data over large distances. Optical data transmission also becomes more and more important within computers themselves”, says Thomas Müller. When large computer clusters work with many processor cores at the same time, a lot of information has to be transferred between the cores. As graphene allows switching between optical and electrical signals very quickly, this data can be exchanged optically. This speeds up the data exchange and requires much less electrical energy.

Industrial Processes Call for Customized Approaches to Wastewater.

Water is a mission-critical resource for industrial firms, and wastewater treatment makes up an important component of many company’s water-management strategy. Increasing water scarcity and stress, along with ever-stricter government regulation, compel industrial firms to seek out ever-more-efficient systems for treating their wastewater.

How do manufacturing and industrial firms treat their wastewater? Although we’re discussing industrial wastewater treatment here, the best place to start is describing conventional treatment processes. Nearly any industrial plant will need to process sewage — graywater and human waste — either through an in-house plant or by feeding it to a municipal facility. For any enterprise large enough to need its own wastewater facilities, the default system would be more or less based on the three stages of primary, secondary, and tertiary treatment.

However, a manufacturing or industrial plant will require that standard model to be altered or augmented, depending on the types of processes carried out at the facility. Michelle Hamm, environmental manager at Monadnock Paper Mills in Bennington, N.H., told me in an interview that “for municipal plants, their largest issue is parasites, things like E. coli. But in industrial treatment systems, each waste stream is different, depending on the actual chemicals used in the facility.” For example, Monadnock’s operations produce large volumes of short paper fiber, so the plant’s sludge-handling process is crucial. Monadnock recovers and treats its sludge in such a way that it can be used by local agriculture for topsoil.

The basic kinds of wastewater treatment processes are physical, biological, and chemical. Physical processes remove solids by such means as screening, skimming and settling. In biological processes, bacteria and other organisms are used to consume organic matter. Chemical processes can be used to act on pollutants in ways that allow them to be more easily removed from wastewater.

A primer from the U.S. Environmental Protection Agency (EPA) explains the three conventional steps in wastewater treatment:

1. Primary treatment removes coarse solids from wastewater after preliminary screening for large floating objects. In a sedimentation tank, suspended solids settle to the bottom, forming primary sludge, which is usually removed using mechanical equipment.
2. In secondary treatment, organic matter is removed using biological processes. According to EPA, the two most common methods for secondary treatment are attached growth processes, in which microbial growth occurs on the surface of a plastic or stone medium; and suspended growth processes, in which microbial growth takes place suspended in the water, which is aerated or agitated to introduce oxygen.
3. Tertiary treatment (a.k.a., advanced treatment) refers to any treatment processes employed after secondary treatment before discharge into the environment. Tertiary treatment can involve filtration, disinfection, odor control, and removal of elements such as nitrogen and phosphorus.

Pretreatment Diverts Contaminants in Advance

The conventional three-stage wastewater treatment process can be negatively affected by toxic chemicals in the waste stream. Such chemicals can disrupt the functioning of standard wastewater processes or can end up being harmfully discharged into the environment.

EPA says, for example, that “chromium can inhibit reproduction of aerobic digestion microorganisms, thereby disrupting sludge treatment and producing sludge that must be disposed of with special treatment.” If they find their way into wastewater, volatile organic compounds (VOCs) can cause gases or vapors to build up in sewer head spaces, sometimes resulting in explosions. Chemical reactions in wastewater can cause poisonous gases to form. Cyanide and acid, says EPA, “both present in many electroplating operations, react to form highly toxic hydrogen cyanide gas.” Similarly, “sulfides from leather tanning can combine with acid to form hydrogen sulfide.”

For these reasons, industrial facilities often have to use pretreatment processes to remove such compounds from wastewaters prior to conventional treatment. Pretreatment in the U.S. is a highly-controlled process falling under the 1972 Clean Water Act (CWA). EPA, in partnership with state governments and publicly-owned treatment works (POTWs) have the responsibility to regulate a National Pollutant Discharge Elimination System (NPDES), which issues permits for industrial firms that emit wastewaters.

Background materials from Munich, Germany-based Siemens AG stress that industrial wastewaters are highly-specific to the facility. Impurities could include “acidic [chemicals] from a plating process, colorings, acids, oils and fats from food processing, or the presence of organic chemicals, such as pesticides, paints, dyes, or detergents.” Pretreatment processes, says Siemens, “can be as simple as chemical addition or as complex as the integration of multiple unit processes for a complete water treatment system.” Pretreatment equipment can be purchased directly or operated on-site through a service contract.

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Siemens cites the case of a utilities company in Texas that had a problem with copper levels substantially higher than those allowed under its NPDES permit. Siemens provided an ion exchange system for removal of heavy metals. The system uses 30-cubic-foot vessels containing cation resin to remove copper from the facility’s wastewater. Siemens is contracted to remove the vessels periodically and take them to a special facility for recovery of the copper and regeneration of the resin. Siemens says that “all residuals from the regeneration process are sent for secondary treatment and recovery” and that “no waste goes to a landfill.” Siemens then ships the regenerated resin back to the utility for reuse.

Tertiary Treatment Provides Final Polishing

As I mentioned above, tertiary treatment really refers to any final advanced treatment processes that prepare wastewater for discharge into the receiving environment, such as a river, lake, wetland, or the ground. Such processes might include further filtration, lagooning, land treatment, or removal of nutrients or other substances. According to Siemens, tertiary treatment technologies “can be extensions of conventional secondary biological treatment to further stabilize oxygen-demanding substances in the wastewater, or to remove nitrogen and phosphorus.” Such advanced treatment can also involve “physical-chemical separation techniques such as carbon adsorption, flocculation/precipitation, membranes for advanced filtration, ion exchange, dechlorination, and reverse osmosis.”

Dow chemical plant in Freeport, Texas. Credit: Dow Chemical Co.

Under appropriate circumstances, land treatment can be a beneficial, lower-cost tertiary alternative. EPA refers to land treatmentas “the controlled application of wastewater to the soil where physical, chemical, and biological processes treat the wastewater as it passes across or through the soil.” The most common land-treatment technique is slow rate infiltration, using the treated wastewater for irrigation. Most nutrients are used by plants, while “other pollutants are transferred to the soil by adsorption, where many are mineralized or broken down over time by microbial action.”

Constructed wetlands are another tertiary strategy. My recent article on green infrastructure detailed three cases of engineered wetlands constructed by The Dow Chemical Co., Alcoa and Shell Petroleum Co. Shell built a constructed wetland at one of its oil fields in Oman, where its wells were bringing up large volumes of water along with the oil. The wetland uses reed beds to filter the water. Microbes break down the oil underground. Not only can such green infrastructure projects provide cost-effective tertiary treatment, but they also create wildlife habitat while eliminating harmful pollutants.

I talked about Dow’s wetlands projects with Gena Leathers, who manages the company’s corporate water strategy. Dow’s subsidiary Union Carbide built a 110-acre wetland at a fraction of the cost of a conventional gray-infrastructure treatment system. Leathers told me that the purpose of the wetland “was to provide a finishing step to reduce solids in the effluent to meet permit requirements. This system, she said, “saved the company many millions of dollars while providing value to nature.” She stressed that “there are many things companies can do to help the company and nature at the same time.”

Modular Battery Concept for Short-Distance Traffic.

Electric mobility may be economically efficient today. Battery-based electric drives can be applied efficiently in urban buses, for instance. Frequent acceleration and slow-down processes as well as a high utilization rate in short-distance traffic make their use profitable even when considering current battery costs. At the IAA International Motor Show in Frankfurt, Karlsruhe Institute of Technology (KIT) will present an e-city bus demonstrator to illustrate the concept.

The key modules of the demonstrator are a drive train with a high-torque electric motor, a high-voltage network, a battery management system, and a novel modular battery system with lithium-ion cells made in Germany. At the IAA, the demonstrator developed for drive tests will present options for the design of the electric drive train of buses.

Using the demonstrator, the innovation potential of KIT's research results can be validated and interaction of the components can be analyzed experimentally under the simulated operating conditions. "In this way, the demonstrator contributes to the further development of electric mobility," Andreas Gutsch, coordinator of the Competence E project at KIT, explains.

The battery system consists of flat modules that can be stacked to reach the dimensions and electric characteristics desired. Various spaces in the different types of vehicles can be used for accommodating the energy storage system. The battery management system and drive control developed for the KIT demonstrator allow for driving operation taking into account the current performance limits of the system and its components.

"Energy efficiency of an electric bus can be increased by an adequate selection of components already," says Martin Gießler, Head of the demonstrator development project. "Of course, an anticipatory operation and recuperation strategy plays an important role." By means of recuperation, braking energy is converted into electrical energy again. The drive consists of a low-torque engine supplying a high driving torque for the vehicle. The engine is connected directly with the differential gear of the rear axle. It decreases the gear reduction to be implemented and, hence, ensures a high efficiency of torque transmission.

The e-city bus demonstrator development project was funded by the Federal Ministry of Economics and Technology