Top 5 Benefits of Using Renewable Alternative Energy

Until some years back, the use of renewable alternative energy wasn't too well known. With time, as the danger of exhausting fossil fuels became a reality, science discovered the use of renewable alternative energy as en excellent way to fuel the energy needs of mankind. As a result, you can observe the use of solar energy, wind energy, water energy and so on, powering the energy needs.

All of this doesn't come with its benefits tied in. The best deal with renewable alternative energy is that you have many ways and methods of processing energy.

Here are the 5 top benefits of using renewable alternative energy

Elimination of solid waste - Every household delivers its share of household waste. By processing this household waste to generate energy, you could take care of a major environmental concern. By doing this, you ensure a clean environment and the dual benefit of generating energy from waste materials also ties in. These energy sources would never exhaust - Unlike coal, petrol and oil which are known to get exhausted with time, alternative energy sources would never run out of stock. For example, the odds of sun losing its heat, is extremely low.

Local production means energy at lower prices - If the developments in some countries could change the fortunes of petrol and oil prices, price changes due to uncontrollable factors is minimized with alternative energy methods. One can generate energy through this method, locally, which means the energy prices would now no longer have to depend on global conditions. Domestic demand meets domestic supply - For example, a society needs 100 MW of surplus power. To meet this power demand, the society could ask their city administration to provide them with surplus power. Alternatively, they could set up a solar power generator and work on self-providing energy. A clean future for mankind - The fact that fossil fuels when burnt or used, release toxic and poisonous gases like Carbon Monoxide, Lead Oxide and so on means they wouldn't be ideal for use, especially in the longer run. The good news is that with alternative energy, you wouldn't have to encounter any such disadvantage.

Out of every 4 individuals, 2 think of using renewable sources of energy for their energy and power needs. This indeed is a good enough transition in the minds of people, but considering the increased emphasis on global warming and pollution due to greenhouse gases, this percentage can only be seen going up.

The Use of Alternative Energy to Help Keep a Green Earth

La gran pregunta hoy es si va a reemplazar y reducir nuestros combustibles de hidrocarburos de dependencia como los combustibles del carbón y del petróleo. Energía alternativa es quizás uno de los más comentados y hablaba de recursos en la sociedad actual como un posible reemplazo de hidrocarburos. Es ha estimado que todos nuestros recursos naturales se habrán agotados completamente dentro de 150 años, y como tal tenemos que estar en continua búsqueda de las fuentes de energía alternativa viables.

Los tipos más comunes de energía alternativa actualmente en uso son la energía eólica, energía de hidromasaje y energía solar. Las fuentes de energía alternativas vayan de fenómenos naturales abundantes en el planeta, y como tales son en esencia libres. Es estas fuentes de energía alternativa que con frecuencia son perseguidas para proporcionar una fuente energética económicamente viable que puede ser utilizada por todo el planeta.

Echar un vistazo a estos tipos de recursos energéticos alternativos, somos capaces de ver las diferencias de cada uno y las ventajas que podrían tener sobre unos a otros como sustitutos de los combustibles de hidrocarburos.

Energía eólica

El uso de la energía eólica, mientras que una fuente de energía alternativa libre, sería en el escenario actual, la fuente de energía renovable más costosa. Los costos son elevados en gran medida en parte al hecho de que se genera viento turbinas deben ponerse en marcha a lo largo de los países con un número suficiente para garantizar la suficiente electricidad para satisfacer las necesidades de la población, esto incluye zonas donde la velocidad del viento no son muy fuertes. El evidente coste de construcción suficiente turbinas capaces de aprovechar la energía alternativa del viento es sorprendente.

Hoy es el uso actual en los países con la fuerza financiera para invertir en energía eólica y donde el clima permite suficiente viento alimentar las turbinas. Sin embargo, muchas granjas y comunidades rurales utilizan turbinas eólicas para proporcionar energía por sí mismos. En números bajos los costos inherentes de construir turbinas eólicas permite esa inversión a pagar por sí mismos muy rápidamente, sin embargo en grandes cantidades los costos aumentando gradualmente y como tal no han sido utilizados por muchos.

Energía solar

Como fuente de energía alternativa [http://www.globalearth.info], la energía solar se deriva el poder natural del sol. Aparte de la instalación del equipo necesario para convertir los rayos del sol en electricidad utilizable es generalmente libre. El costo del equipo necesario para aprovechar el poder del sol en los últimos días ha vuelto menos caro, principalmente debido a los avances en la tecnología. El costo de inversión para pequeñas instalaciones generalmente pagan por sí mismos con unos años más o menos.

Muchos de los viven en zonas tratando de ahorrar energía por tener rodando apagones a diario. Esto ya no es una preocupación para aquellos que utilizan la energía solar! Cuando se utiliza energía solar para alimentar su casa, mientras el generador está activado, tienes poder. La forma de que trabajan de estos generadores, es que durante el día la energía del sol se dibuja en el generador en celdas de almacenamiento. El generador convierte la energía solar almacenada en energía utilizable para su hogar. Esto significa que, incluso cuando el resto de la ciudad está bajo un apagón, tu casa puede seguir ejecutándose suavemente sobre energía solar.

Para los muchos que viven en zonas que están tratando de ahorrar energía por día y utilizando rodando día de apagones, el uso de la energía solar permite flexibilidad y pérdida de poder regular ya no sería un motivo de preocupación. Utilizando la energía solar en casa sólo requiere su generador esté activada para tener la potencia necesaria cuando se producen los apagones. Estos generadores funcionan de manera que durante el día la energía del sol se dibuja en los generadores a las celdas de almacenamiento y luego generador convierte la energía solar que se ha almacenado en las células en energía eléctrica utilizable para que una se utiliza en los hogares. En pocas palabras, apagones intermitentes o programadas permite todavía la casa todavía tener electricidad con esta fuente de energía alternativa.

Material necesario para construir sistemas para hacer uso de la energía solar como una fuente de energía alternativa para los hogares puede adquirirse fácilmente en la mayoría de las tiendas mejoramiento del hogar en las Naciones desarrolladas y ser instalada fácilmente en unas pocas horas. Paneles solares son fáciles de instalar en su cuenta, sin embargo hacerlo usted mismo a veces puede ser difícil, pero normalmente son contratistas que pueden hacer el trabajo de instalación de los paneles solares y generadores a un costo razonable.

Hydro Power

El uso del agua ha sido durante mucho tiempo en existencia particular su uso como un reemplazo de mano de obra, y también hay evidencia de algunos del primer uso comercial de hidromasaje poder como una energía alternativa están todavía en existencia hoy en el tan evidentes de fresado viejo y las instalaciones industriales. Hidromasaje poder hoy en día es poder productos utilizados en las escalas más grandes y las construcciones de represas y instalaciones de hidromasaje está aumentando debido a las preocupaciones sobre los recursos de hidrocarburos naturales agotamiento rápido.

Sin embargo, el uso de la potencia de hidromasaje y fuente de energía alternativa es limitado a zonas donde el agua es abundante y permite que el terreno natural para que pueda ser aprovechada en orden a turbinas que generan la electricidad necesaria. Algunos propietarios han sin embargo en los últimos tiempos comenzaron a dispositivo y desarrollar dispositivos para producir pequeñas cantidades de electricidad suficiente las necesidades de su hogar o granja al aire libre.

Mantener la tierra verde!

Utilizando fuentes de energía alternativas como la energía solar para proporcionar energía a su hogar es una de las mejores maneras en que puede ayudar a mantener la tierra verde! Energía solar no necesita quemar combustibles fósiles y de hidrocarburos y como tal le proporciona la energía necesaria sin agotar los recursos de tierras, teniendo en cuenta que en nuestras vidas no hay posibilidad de agotamiento de la energía del sol. El uso de esa energía alternativa asegura también que hacer su parte en mantener el medio ambiente más sano y limpio ya que no en todas formas contribuyen al agotamiento de los recursos naturales.

Independientemente de qué tipo o fuente de energía alternativa que decide utilizar para sus hogares, el hecho es que seguimos necesitando una fuente viable de energía renovable que puede ser utilizado por todo el mundo pronto, como el más largo que se tarda en encontrar esto, los recursos naturales más empobrecidos y agotados.

Lithium air batteries

As an alternative to conventional vehicles, electric vehicles are one of the promises of the future. Because they cause less pollution and not dependent on fossil fuels, electric vehicles are a viable option for transport over the coming years. However, not everything is as simple as it seems.

In recent years, a number of studies have been conducted to be able to judge the popularity of the vehicles electrical. And while there are many people who would love to buy these Green cars also there are a lot of people who prefers the traditional gasoline vehicles.

Why? Well, the answer is quite simple: EVs have no conventional speed of vehicles , have less autonomy and there is also a lack of facilities for cargo. But perhaps the most important factor is the cost, even with the tax facilities in many countries is the purchase of an EV, many people cannot afford them.

To partly offset these problems, scientists have developed litio-aire batteries for electric vehicles. Thanks to the implementation of this technology be could, for example, provide a better range of autonomy for so electric vehicles can travel longer distances.

The litio-aire batteries used two electrolytes: a metal (lithium) and the other is oxygen. Now, generally each battery has an anode and a cathode. When chemical reactions take place, the electric current flows through the battery. In the litio-aire batteries, there is a cathode, oxygen. The batteries are operated to come into contact with the oxygen present in the atmosphere. That allows to be light in weight.

When they are commercially available and if all goes as planned, the batteries of litio-aire bring us closer to a future better and greener. Lithium air batteries have the ability to store a huge amount of energy: up to 5,000 watt-hours per kilogram.

This is even more than the hydrogen fuel cells. The batteries of litio-aire is estimated to have capacity of up to five to ten times more energy storage than a lithium-ion battery. Thus, with these batteries in the car, there will be need to recharge the vehicle each one few hours in case that you want to travel great distances.

The main difficulties of the lithium air batteries

The batteries of litio-aire have their share of disadvantages. Although some assume that once it succeeds in passing, they probably revolucionarán have an EV.

Firstly, the remains of the reactions accumulate in the cathode in the batteries of litio-aire. This makes the passage of air difficult.

Secondly, the automotive industry itself is so great, that a large amount of lithium would have to be used to provide a massive production EVs with battery litio-aire. This is a gigantic task. Thirdly, the manufacture of the litio-aire batteries cost a fortune, and it is still difficult to such spending and investment is seen as profitable commercial eyes business's most important automobiles of the world.

How electricity: which is an electric field

In the 18th century, thanks to research of Coulomb, could be established that electric charges interact at distance, as well as the mass against gravitational forces. I.e., that a mass or load might inexplicably, without any mediator to notice another in their environments.

This idea was uncomfortable with physicists, even to the own Newton. Faraday proposed an alternative interpretation of very useful, based on the idea of field: space surrounding an electric charge is affected by its presence, since it modifies its characteristics.

In his attempt to represent him, Faraday described as invisible tentacles that are moving from the load. In this way, from the moment in which a body takes charge, this information or novelty is stretching in your environment quickly, indeed to the speed of light, and can eventually reach another load.

As it is true to speak of the interaction between a load and another, it is possible to also describe the same incident from the interaction of a cargo area that is.

To electric field can represent it with lines, by Convention, out of the positive charges and entering the negative charges. They indicate the direction of the field at every location, i.e. the direction of the electric force which would experience a timely and positive, load called burden of proof, if it is placed at each position in the field.

The number of lines is proportional to the intensity of the field, IE where the lines are very close, the field is large and where they are separated, the field is small.

Despite the many similarities between the actions electric and gravitational, should be clarified a difference: the gravitational field is always inlet to its source (a mass) while the electric field can be incoming or outgoing on the load that is generated, there are two different kinds of load.

View electric field requires some care, although it is possible to do it with some simple experiences. The simplest is to observe the direction of the hair covering the forearm when, for example,
We are approaching a bowed plastic rule.

Is also possible to obtain a representation at the level of the electric field linesor in the following manner: put a mixture of oil for the body and very small pieces of human hair, no more than 2 mm of
long, on a flat glass, such as a microscope slide. If we bring a charged object, observe that the orientation of the pieces of hair will follow the electric fieldlines.

Representation of electric fields created by positive and negative point charges.

Read more on electricity:

It is electricity

Learn how electricity

Conductive and insulating materials

Roads that generate electricity

Magnetic bacteria, which generate electricity

View the original article here

New Cleantech Technology News (Say What?)

Aside from the cleantech project, cleantech policy, cleantech consumer product round-ups I’m in the midst of finishing, here’s a round-up of some of the latest news on new cleantech technology:

1. Wind Energy Forecasting Technology Saves Millions of Dollars a Year

“The National Center for Atmospheric Research (NCAR) has developed a highly detailed wind energy forecasting system with Xcel Energy, enabling the utility to capture energy from turbines far more effectively and at lower cost,” the University Corporation for Atmospheric Research reports. “The system, which Xcel Energy formally took over last month, saves ratepayers several million dollars yearly.”

Basically, the new technology gives wind forecasts that are 35% more accurate. This allows the utility to power down costly coal and natural gas power plants more often. In 2010, the technology reportedly saved Xcel Energy $6 million.

The technology is used in Colorado, Minnesota, New Mexico, Texas, and Wisconsin.

2. Gamesa Wind Turbine Setting Records in Spain

“Gamesa’s new 4.5 megawatt G128 has posted a new record at a test field in Jaulin near Zaragosa, Spain,” Renewables International reports. “On November 7, it generated 97.34 megawatt-hours in a single day with 100 percent availability.” Since the start of 2011, this prototype wind turbine has fed over six gigawatt-hours to the Spanish grid. “With a rotor diameter of 128 meters and an output of 4.5 megawatts, the new G128 has a 120 meter tower and rotor blades whose diameter exceeds 62.5 meters.”

3. Shakeup in Grid Storage Technology Market, 5 Leaders Revealed

OK, grid storage is probably not something most of you go to sleep thinking about, but it’s important, and there’s a lot going on in this field.

The new Lux Research Grid Storage Tracker reveals that the lineup of leading emerging energy storage suppliers is indeed seeing a significant shake-up. Japanese molten salt battery producer NGK Insulators has historically dominated the grid storage market for emerging technologies (excluding pumped hydro, compressed air, and traditional lead-acid batteries). After capturing over 76% of the total market at the end of 2010, NGK’s market share plummeted to just 53% of operating grid storage projects as of September 30th of this year, according to Lux Research’s Grid Storage Tracker.

2011 Installed Grid Storage
Market Leaders

NGK’s monopoly withered and allowed other players with a variety of technologies to make waves into the grid storage market, including Xtreme Power’s advanced lead acid battery, Beacon Power’s flywheels (although Beacon’s share will drop after filing Chapter 11 last week), and lithium ion batteries from International Battery and A123 Systems. The strong traction of these players resulted in a 56% increase in the number of installed megawatts in 2011 over 2010. Based upon announced and ongoing projects, NGK’s market share will sharply drop by the end of 2012 with A123 Systems capturing nearly one quarter of the market.

4. Virtual Power Plants to Boom

Confused? Read on…

Growing investments in distributed energy resources – renewable distributed energy generation, demand response (DR), energy storage, and plug-in electric vehicles (PEVs) – will require new business and technology platforms to manage the increased level of diversity and complexity in the delivery of electricity to customers.The increasing variability of both generation (from solar and wind) and loads (due to DR and PEVs) will also require more sophisticated and decentralized decision making. As a result of all of these factors, interest in virtual power plants (VPPs) is gaining significant momentum within the industry. According to a new report from Pike Research, VPP capacity will increase by 65% between 2011 and 2017, rising from 55.6 gigawatts (GW) to 91.7 GW worldwide during that period. A more aggressive growth forecast scenario contemplates that, under certain conditions, the capacity growth could be as high as 126% during the same forecast horizon.

“Virtual power plants essentially represent an ‘Internet of Energy’, tapping existing grid networks to tailor electricity supply and demand services for a customer,” says senior analyst Peter Asmus. “They maximize value for both the end user and distribution utility, primarily through software innovations.”

5. 2011 Clean Energy Challenge Finalists Getting Funding

It’s a long road to commercialization, and many don’t make it, but here are some that might:

… several inaugural Clean Energy Challenge finalists have secured more than $9 million in venture funding, expanded operations and furthered the commercialization of new clean energy technology following their participation in the 2011 business competition.

The top prize winner, Clean Urban Energy (CUE), recently closed a $7 million A-round led by Battery Ventures, a Challenge judge. CUE has also hired 10 full-time employees since its win.

NextGen Solar, the second place winner, is currently completing development of its first functional prototype. The company also presented at the prestigious national Renewable Energy Laboratory Growth forum and was a semi-finalist at the Cleantech Open.

Other notable achievements include:

Thermal Conservation Technologies was among ten companies invited to present at CTSI Defense Energy Challenge. It hired Dr. Pratek Gupta as its first full-time employee, charged with completing the company’s prototype.Intelligent Generation: Presented at the National Renewable Energy Laboratory Industry Growth forum and launched a two-phased pilot project with ComEd and PJM.Power2Switch: Hired three full-time employees and launched a new website with energy consumption and analytics functionality.Agentis: Has a live product with more than 78,000 users and is embarking on multiple pilot projects with large utilities.Root3 Technologies: Is conducting a pilot project with the University of Chicago and negotiating an exclusive technology license with Stanford University.Sun Phocus Technologies: Is now generating revenue, conducting two pilot projects, and has partnered with an Israeli manufacturer identified by the Clean Energy Trust.

6. University of Ottawa Students Design New Wind Turbine

“Over at the University of Ottawa, a group of students and professors who dub themselves the ‘Green Engineers‘ have come up with… a wind turbine with two sets of blades each spinning in opposite directions,” Tyler Hamilton of the Toronto Star reports.

They call it the contra-rotating small wind energy converter. Wind tunnel tests on a prototype have shown that the design is up to 40 per cent more efficient and far less noisy than a conventional single-rotor system.

The benefits of having contra-rotating blades are well known. In fact, the design has existed for more than a century and is widely used, for example, in propeller systems of submarine torpedoes. The concept is also used in airplane and boat propulsion systems, not to mention those remote-controlled toy helicopters you can fly inside your house.

Riadh Habash, professor of technology and engineering at the University of Ottawa, says his team decided three years to apply the same approach to wind turbines and are encouraged so far with the results — so much so that they’re busy building a second prototype that will be mounted next summer atop a building on the Ottawa U campus.

Why is having two blade systems spinning in opposite directions more efficient?

When the wind blows into a conventional three-bladed, single-rotor wind turbine less than 40 per cent of its energy is converted into electricity. The rest escapes, much of it in the air wake that’s created behind the blades. That wake spins in the opposite direction (i.e. counter-clockwise) to those blades.

If a second rotor with another set of blades is right behind the first rotor, and if it is designed to also spin counter-clockwise, it can capture energy from that wake. The end result is a turbine system that harnesses much more energy from the initial flow of wind.

Experiments to date also suggest that a turbine with such a design can operate at lower wind speeds, allowing it to tap into a broader range of wind resources.

The turbine is, apparently, also quieter.

7. Vehicle to Grid Technology to Boom

“Vehicle to grid (V2G) technologies, over time, will represent a more and more favorable alternative to investing in new power generation assets,” according to a news release earlier this week. “By 2017, according to a new report from Pike Research, approximately 90,000 light-duty vehicles and an additional 1,500 medium/heavy duty trucks will be enabled with V2G technologies, creating a strong foundation for V2G-based demand response, vehicle to building, frequency regulation, and other ancillary service applications.”

“V2G technologies are currently in the early pilot phase, with much work left to do before they will be ready for full commercialization,” says research director John Gartner. “The earliest adopters will be fleet operators and large consumers of energy where vehicles have established schedules for being plugged in. As the sector develops, V2G will be utilized for an increasing array of grid support services.”

8. Ground-Based Wind Turbine

Next-Gen Wind reports:

“Based off the current patents, NGW created a completely novel ground based wind energy super turbine that can increase wind velocity by 79 percent and produce nearly 2x the energy of a traditional wind tower turbine unit with the same swept area (see data Figure 2). NGW’s super turbine increases the velocity of the wind as it travels through the patented funnel shaped wind collection unit. More specifically, the funnel shaped wind ‘collector’ is increasing volume density of the air mass which is then forced through a smaller tunnel where the multi-blade wind energy collection rotors and generators are located. The resulting concentration allows for optimal generating wind velocities, and provides the opportunity to harvest a larger fraction of the kinetic wind energy passing through the system, when compared to a traditional tower-based wind turbine platform.”

9. GE: Hybrid Gas-Solar-Wind Power Plant is the Answer

“General Electric is pinning its hopes on a new hybrid gas and solar energy generator to help drive down the high cost of solar thermal energy and reduce the need for extra power plants to back up intermittent wind power,” Business Green reports.

“The company last week received approval from the Turkish government to nearly double the output of the world’s first Integrated Renewables Combined-Cycle plant from 570 megawatts (MW) to 1,080MW, and hopes the expanded facility can provide a template for other low carbon energy projects around the world.”

10. High-Rise Rooftops Can be Wind Farms, Too

“Eastern Wind Power (EWP) is a Cambridge, Mass.-based startup that has developed a 50-kilowatt (kW) vertical-axis wind turbine (VAWT) called the Sky Farm,” EarthTechling reports. “The VAWT is designed specifically to be mounted on the roofs of high-rise buildings. The company has partnered with Siemens to develop its small wind generator and inverter system. The company erected its first prototype Sky Farm at the Martha’s Vineyard Airport in 2010. The turbine is now grid-connected, and producing power for the airport.”

The electric current

In Erenovable continue marking some of the key concepts necessary to understand how electricity..In this case we will make sure to clarify a concept which, while use you on a daily basis, we do not always understand completely: the current electric.

At the beginning of the 19th century, was one of the great advances on the way to the electric power generation. It was invented by Alessandro Volta: the stack. This revolutionary object was the first electrochemical device that could be used as a source of electricity, able to deliver energy in a continuous and stable.

From there, the electrical phenomena research advanced rapidly. Some of the most important postulates that could establish were:

the electric charge is in more or less linked nature in the structure of materials, i.e. with greater or lesser ability to move in response to its interaction with electric fields..the negative charge residing on the electrons is, more often, is free, for example in metals. in them, some of the electrons have a degree of freedom like the molecules in a gaseous state. Their movement is erratic, and in gas, not a net sense of movement can be recognized.

Following this series of laws, you could discover that when you install a field within a metallic conductor, particles tend to follow preferably the signal from the field and can then be a sense of movement in their movements. This is what we call electric current.

Like most of the drivers of electric circuits are metallic, it is necessary to be in them the sense real or physical movement of the electrons against the electric field.

In the electrolyte or gaseous conductors, the charge carriers can also be positive, so that their displacement is contrary to the previous.

For simplicity, establishing a conventional sense of the current movement and is the positive charge carriers, i.e. in favour of the electric field.

Do do is defined as the electrical current to the ratio between the NET burden ? q that crosses a certain section of the driver per unit time? t. In symbols:

The unit of electric current is the ampere (A) that corresponds to a constant current which a load of a coulomb is going through any normal section of the driver by every second.

Its name was chosen in homage to the contributions of the French André Marie Ampère (1775-1836), who at the beginning of the 19th century established the principles of electrodynamics, relating the concepts of electricity and electrical potential, and also made other important contributions in the theory of electricity and magnetism.

Still learning more about the theory of electricity in these special items:

New Research Shows United States' Accessible Geothermal Energy is Enormous

A recent study performed by Southern Methodist University (SMU) shows the technical power potential of enhanced geothermal systems is immense.

Through its research, SMU was able to create the most data rich map of U.S. geothermal resources to date. According to the thermal data, the United States houses more than 2,980,295 megawatts of geothermal energy that could be harnessed using EGS and other advanced geothermal technologies.

It comes as no surprise that the majority of the capacity is located in the western half of the country. Nevada and Idaho each hold the most potential, while Montana, New Mexico, Arizona, Utah, and Colorado each house significant resources.

In America's renewable energy sector, geothermal has been much slower in developing itself compared to the solar and wind industries. According to the U.S. Geothermal Energy Association there was 3,086 MW of installed geothermal power in America in 2010. This pales in comparison to installed wind and solar power. For example, as of June 2011 there was 42,432 MW of wind power in America.

There are several reasons for the slow development of the industry. A major contributing force, however, is technology. In 2009, EGS burst on to the scene as an advanced technology which would allow geothermal energy to be tapped at a groundbreaking rate. Both the public and private sector pumped money into EGS projects, but to date these projects appear to have raised more questions than solutions.

California-based advanced geothermal developer AltaRock has abandoned a project after it ran into drilling problems. EGS projects have also come into question about whether or not they induce earthquakes as a result of seismic shifts created by their drilling.

Nevertheless, geothermal energy offers an incredible baseload clean energy option as it does not rely on intermittent catalysts like sunshine or wind. Corporate giant Google, Inc. remains one of the biggest private-sector proponents of EGS technology. The company has invested nearly $11 million to help advance enhanced geothermal systems.