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renewable energy, Renewable Energy

Fuel Cells- Definition, Advantages and Future

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Fuel Cells is a hot topic among scientists these days thanks to their wide range of applications. Their uses are so diverse that fuel cells have found a place even in the space program. In this blog, let me explain in detail the design, working, types and future scope of fuel cells.

Shall we begin?

What are Fuel Cells?

Fuel cells are electrochemical cells that use a pair of redox reactions to transform the chemical energy of a fuel (typically hydrogen) and an oxidizing agent (usually oxygen) into electricity. It finds various applications, including transportation, industrial/commercial/residential structures, and long-term grid energy storage in reversible systems.

Fuel cells are unique in that they may use a wide range of fuels and feedstocks and can power systems as large as a utility power plant and as small as laptop computers. Now, we are moving on to the design of fuel cells.

Also read: Solar Energy- Definition, Advantages, and Future

Fuel Cells Design

A fuel cell comprises 3 adjacent segments namely the anode, the electrolyte, and the cathode. At the intersections of these segments, redox reactions take place. Fuel is burned, water or carbon dioxide is produced, and an electric current is produced, which can be utilized to power electrical devices, commonly referred to as the load.

A fuel cell’s design elements include:

  • An electrolyte – It acts as a medium of transport between the electrodes. Most common electrolytes include potassium hydroxide, salt carbonates, and phosphoric acid, and it usually defines the type of fuel cell.
  • A fuel – The fuel undergoes oxidation reaction and supplies the ions. Hydrogen is the most common fuel.
  • Anode Catalyst – It breaks down the fuel into electrons and ions. We usually use fine platinum powder as the anode catalyst.
  • Cathode catalyst – It reacts with the ions that reach the cathode and transforms them into harmless compounds, the most common of which is water.
  • Gas diffusion layers that are resistant to oxidation.

Let me show you how fuel cells produce electricity from the fuel we supply.

Fuel Cells Working

In 1839, Sir William Robert Grove, a physicist invented the first fuel cell. The goal of a fuel cell is to generate an electric current that can do some work outside of the cell, such as powering an electric motor or lighting a city.

A catalyst at the anode promotes oxidation reactions in the fuel. As a result, hydrogen atoms are stripped of their electrons at the anode of a fuel cell. The hydrogen atoms have now become positively charged H+ ions.

At full rated load, a typical fuel cell produces a voltage of 0.6 to 0.7 V. If we require alternating current (AC), we must channel the DC output of the fuel cell via a conversion device called an inverter.

Reactions inside Fuel Cell

When the ions and electrons reach the cathode, they rejoin, and the two react with a third molecule, usually oxygen, to produce water or carbon dioxide. The following are the basic reactions that take place inside a fuel cell:

Anode side:  2H2 => 4H+ + 4e–  

Cathode side: O2+ 4H++ 4e–=> 2H2O

Net reaction: 2H2 + O2 => 2H2O

Fuel cell reaction

Different types of fuel cells

Depending on the electrolyte in use, there are different types of fuel cells. Here are some of them:

Alkali Fuel Cells

  • Alkali fuel cells use compressed hydrogen and oxygen to function.
  • Their electrolyte is usually a solution of potassium hydroxide (chemically, KOH) in water.
  • The efficiency is around 70%, and the operating temperature is between 150 and 200 degrees Celsius (about 300 to 400 degrees F).
  • The output of the cells ranges from 300 watts (W) to 5 kilowatts (kW).
  • However, they require pure hydrogen fuel, and their platinum electrode catalysts are costly. They can also leak, just like any other liquid-filled container.
  • In the Apollo spacecraft, alkali cells were employed to produce both electricity and drinking water.

Molten Carbonate Fuel Cells

  • The electrolyte of molten carbonate fuel cells (MCFC) consists of high-temperature salt carbonates (chemically, CO3).
  • The efficiency ranges from 60% to 80%, and the working temperature is around 650°C (1,200 degrees F).
  • The high temperature prevents the poisoning of cell by carbon monoxide, and waste heat can be recycled to generate more energy. However, the high temperature limits the materials and applications of MCFCs–they are likely too hot for domestic use.
  • In addition, the processes consume carbonate ions from the electrolyte, necessitating the injection of carbon dioxide to compensate.

Also read: Tidal Energy – Definition, Advantages, and Future

Phosphoric Acid Fuel Cell

  • The electrolyte of PAFCs is phosphoric acid, which is a non-conductive liquid acid that causes electrons to go from anode to cathode via an external electrical circuit.
  • Since the anode’s hydrogen ion generation rate is low, we use platinum as a catalyst to boost the ionisation rate.
  • The use of an acidic electrolyte is a major disadvantage of these cells. This accelerates the corrosion or oxidation of phosphoric acid-exposed components.
  • The operating temperature is between 150 and 200 degrees Celsius, and the efficiency ranges from 40 to 80% (about 300 to 400 degrees F). Phosphoric acid cells now available have outputs of up to 200 kW.

Solid Oxide Fuel Cells

  • Solid oxide fuel cells (SOFC) use a hard, ceramic composition of metal oxides such as calcium or zirconium as an electrolyte.
  • The efficiency is around 60%, and the output of the cells can reach 100 kW.
  • The working temperature is around 1,000 degrees Celsius (about 1,800 degrees F).
  • Further energy generation through waste heat recovery is possible. The high temperature, on the other hand, limits the applications of SOFC units, which are typically quite big.

Let’s have a look at the different applications of fuel cells.

Fuel Cells Applications

Fuel cell technology has a variety of applications. Currently, scientists are carrying out extensive research to develop a cost-effective fuel cell-powered automobile. The following are a few examples of the uses of this technology:

  • Fuel cell electric vehicles, or FCEVs, use clean fuels and are thus more environmentally benign than vehicles powered by internal combustion engines.
  • Many space voyages, like the Appolo space program, have relied on them for power.
  • In many rural regions, fuel cells are a major backup source of electricity.

Also read: Wind Energy: Definition, Advantages, and Future

Fuel Cells Advantages

Fuel cells outperform traditional combustion-based technologies, which are now in operation in many power plants and automobiles. They emit fewer greenhouse gases and zero atmospheric pollutants that contribute to smog and health issues. When pure hydrogen is the fuel, the only byproducts are heat and water. Traditional combustion systems use significantly more energy than hydrogen-powered fuel cells.

Fuel Cells Future

Hydrogen is the most abundant element in the universe, and a hydrogen ecosystem focusing on fuel cell technology has enormous promise. Unlike batteries, we can scale up fuel cell technology for passenger vehicles, buses, ships, and trains. Hydrogen will also power urban air mobility in the future.

Fuel cells could power our cars in the future, with hydrogen replacing the petroleum fuel currently used in most vehicles. Many automakers are investigating and developing transportation fuel cell technologies. Hyundai is pioneering hydrogen fuel cell technology in addition to increasing its array of battery, hybrid, and plug-in electric vehicles.

Shall we wrap up?

Conclusion

Due to its non-polluting nature and a vast range of applications, the future looks bright for fuel cells. Once we are able to cut down the cost of fuel cells and devise methods for the safe and long term storage of hydrogen, fuel cells would revolutionize the energy sector.

In case of any queries, please feel free to ask in the comments section. Happy Learning!

renewable energy

Tidal Energy – Definition, Advantages and Future

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Tidal Energy available worldwide adds up to nearly 3,000 gigawatts. The Romans were the first to think of tapping into this vast energy reserve and using tidal energy to turn wheels and grind grains. In comparison to wind and solar energy, tidal energy has struggled to gain widespread acceptance.

Since tidal power plants are expensive to construct and have other disadvantages that we’ll discuss later in this guide, they aren’t as popular as other renewable energy sources. However, we anticipate tidal energy to grow in popularity in the future years. Here’s all you need to know about how it works, the benefits and drawbacks, and the future for tidal energy.

What is Tidal Energy?

Tidal energy is a form of renewable energy in which we convert the tidal action in the ocean to electric power. It takes advantage of the natural rise and fall of coastal tidal waters.

The interaction of the Sun’s and Moon’s gravitational fields generates these tides. The variation in water level generated by tides includes a lot of potential energy. We convert this potential energy to electrical energy in a tidal power station.

Floodtide or high tide refers to the highest level of tidal water. Low tide, often known as ebb, is the lowest level. The tidal range is the height difference between high and low tide. Only tidal ranges of 5 meters or greater are deemed acceptable for power generation. The largest tidal power station in the world is the Sihwa Lake Tidal Power Station in South Korea, which generates 254 MW of electricity. 

Also read: Solar Energy- Definition, Advantages and Future

Types of Tidal Energy

Currently, we obtain tidal energy in three ways:

  • Tidal streams
  • Barrages
  • Tidal lagoons

Let’s have a look at each one of them in detail.

Tidal Stream Generators

Tides form a fast-flowing body of water known as a tidal stream. We place a turbine in this tidal stream to convert the tidal energy to electrical energy. A turbine is a mechanical device that extracts energy from a fluid flow. Tidal stream generators use the kinetic energy of flowing water to power turbines, just like wind turbines that use the wind to power windmills.

Interested to know more about wind energy? Why don’t you go through our blog Wind Energy: Definition, Advantages, and Future

Depending on the size of the turbine and the location of the tidal stream, the environmental impact could be severe. In shallow water, turbines are most effective. This generates more energy while also allowing ships to manoeuvre around the turbines. The turbine blades of a tidal generator rotate slowly, which helps marine animals from becoming entangled in the system.

tidal energy turbines
tidal energy turbines

Barrage

A tidal barrage is a giant dam built in the ocean to harness tidal energy. Turbines inside the barrage harness the power of the tides in the same way that a river dam does. As the sea rises, the barrage gates open. The water is subsequently discharged through the barrage’s turbines, which generate energy. The barrage gates close at high tide, forming a lake or tidal lagoon.

Barrages, like tidal streams, can have a significant impact on the ecology because they isolate a place from the rest of the ocean. The tidal lagoon’s changing water level could impact plant and animal life.

The salinity of the tidal lagoon decreases, affecting the organisms that can live there. Fish are stopped from entering or leaving the tidal lagoon, much as dams across rivers. Turbines in barrages move swiftly, and marine animals can be stuck in the blades.

A barrage is substantially more expensive than a single turbine for generating tidal energy. Despite the lack of fuel expenditures, it requires more building and machinery. Barrages, unlike single turbines, require regular supervision to modify power output.

Also read: Dams- Components of dam – 12 dam components explained

Tidal Lagoon

A tidal lagoon is a body of ocean water that is partly enclosed by a natural or manmade barrier. Tidal lagoons might also be estuaries and have freshwater emptying into them.

A tidal energy generator using tidal lagoons would function much like a barrage. The turbines work as the lagoon is filling and emptying. Unlike barrages, we can construct tidal lagoons along the natural coastline. A tidal lagoon power plant could also generate continuous power.

Tidal lagoons have a negligible environmental impact. We can use natural resources such as rock to build the lagoons. At low tide, they would show as a low sea wall and at high tide, seawater submerges them. Smaller organisms could swim inside the structure, and animals could swim around it. Large predators such as sharks would be unable to enter the lagoon, allowing smaller fish to thrive.

However, the energy output from tidal lagoon generators is usually low.

Tidal Energy Advantages

Let me show you some of the reasons that make tidal power an attractive option.

Renewable

The combined effects of the moon’s and sun’s gravitational forces, as well as the earth’s rotation cause tides. The difference in the potential energies of the high and low tides allows for tidal energy power generation. Since tides would be present as long as the Earth exists, tidal energy is inexhaustible and non-renewable.


Green

Tidal energy power plants don’t emit any hazardous gases. Also, it doesn’t emit any carbon. Hence it is a green and environment-friendly source of energy. One of the key advantages of tidal energy is that it requires relatively little space to produce energy.

Predictable

Waves and tidal currents are extremely predictable. The ocean develops high and low tides according to some well-known cycles. This makes developing a system with precise dimensions to generate energy easier because we already know what kind of waves the equipment will be exposed to.

Efficient even at Low Speeds


Because water has a significantly higher density than air, it is feasible to create electricity at relatively low speeds. A water speed of roughly 1 m/s can potentially create power. Wherever we employ, tidal energy generators produce a continuous, reliable stream of electricity

Tidal energy
Tidal energy

Tidal Energy Disadvantages

Here are some of the reasons why tidal power plants are not as common as other renewable energy power plants.

Impact on the Environment

While putting tidal generators beneath the water may be handy for people, it is not so for all sea creatures. Since the tidal energy systems rely on turbulent water to operate, we require a substantial foundation. This form of underwater construction has the potential to destroy marine habitats. The turbines can trap fishes, turtles, sewage and also injure them.

High Construction Costs


Building structures that can survive the turbulence and corrosive nature of seawater is not a cheap endeavour. Other renewable resource solutions are less expensive upfront. While tidal energy systems have a long life cycle and eventually pay for themselves, the initial investments are quite high.

Scarcity of Appropriate Locations

A tidal energy facility is not ideal for every seascape near a shore. To function successfully and efficiently, they require a highly specific collection of elements.

Only those areas where we have a tidal range of about 5 m or more, and suitable geography provides a desirable site for the economic construction of a tidal power plant. One of the key reasons for their lack of popularity is the scarcity of suitable areas for establishing tidal power systems.

Tidal Energy Future

Tidal energy future
Tidal energy future

Although tidal energy is still in its infancy, it has the potential to have a major global influence. The value of the tidal energy sector, which was assessed at $487 million in 2014, is expected to increase to $11.3 billion by 2024, according to analysts.

Is it possible for tidal power to take the place of fossil fuels? It can’t do it on its own – but with the collective energy of the wind, sun, and tides, as well as specific energy storage devices, we might be able to make the transition to a green future.

Shall we wrap up?

Conclusion

Tides are without a doubt storehouses of energy. If we can properly tap into its potential, it would be a giant leap towards generating renewable energy and completely stopping fossil fuel usage. Let’s utilise the maximum of this green energy that mother nature has hidden in tides.

In case of any doubts, feel free to ask in the comments section. Happy Learning.

renewable energy, Wind energy

Wind Energy: Definition, Advantages, and Future

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Wind Energy is one of the booming clean energy technologies. According to IRENA’s latest data, global installed wind-generation capacity onshore and offshore has expanded by about 75 times in the last two decades, from 7.5 gigawatts (GW) in 1997 to 564 GW in 2018.

Ever wondered how those massive rotating turbines powered up an entire locality? Join me on this journey to a wind farm exploring the wind turbines, their working, advantages and disadvantages. Let’s get started

What is Wind Energy?

Wind energy or wind power refers to the process of using the wind to generate mechanical or electrical power. This mechanical energy can be employed for specialized purposes such as pumping water or it can be converted to electricity using a generator.

A wind farm is a collection of wind turbines that are all located in the same area. A huge wind farm can include hundreds of separate wind turbines spread out over a vast region. The Gansu Wind Farm is the world’s largest wind farm. We can utilize the land between the turbines for farming or other activities. In a fully established wind farm, we place a distance of 7D (7 times the rotor diameter of the wind turbine) between each turbine.

Individual turbines in a wind farm are linked by a medium-voltage power gathering system and a communication network. This medium-voltage electric current is boosted in voltage by a transformer at a substation before being connected to a high-voltage electric power transmission system.

Let’s understand the working of a wind turbine.

Working of Wind Turbine for Wind energy

The aerodynamic force from the rotor blades, which act similarly to an aeroplane wing or helicopter rotor blade, converts wind energy into electricity in a wind turbine. The air pressure on one side of the blade lowers when the wind blows across it. This difference in air pressure across the two sides of the blade generates lift and drag.

The lift force is greater than the drag force, causing the rotor to spin. The rotor is connected to the generator directly or through a shaft and a series of gears that speeds up the rotation. The conversion of aerodynamic force to the generator’s rotation generates power.

Wind Turbine
Wind Turbine

Equation for Wind Power

The power that a wind turbine generates, P = 0.5 DAV3

where D = Density of the air

V = Wind Speed

A = Swept area of the turbine

Let me explain in detail how each parameter affects wind power.

Wind Speed
The quantity of energy in the wind is proportional to the cube of the wind speed; ie, if the wind speed doubles, the amount of energy in the wind increases by eight times. Hence we can understand that wind speed fluctuations have a significant impact on the quantity of power available in the wind.

Density of Air

The denser the air, the greater the energy the turbine receives from the wind. The density of the air changes with altitude and temperature. Higher elevations have less dense air than sea level, while warm air has less density than cold air. Turbines will produce greater power at lower elevations and in areas with cooler average temperatures, assuming all other factors are equal.

The swept area of the turbine

The larger the swept area which is the region through which the rotor rotates, the more wind power the turbine can capture. Since swept area (A= pi*r2) is proportional to the square of the radius of the rotor, a slight increase in the length of the blade length leads to a greater increase in the power available to the turbine.

Wind Energy Advantages

Wind energy is a cost-effective choice for many places of the world because it does not require direct sunshine exposure like solar energy. It offers several advantages such as:

Free Fuel

There is no need for extra fuel since wind turbines run only on the power supplied by the wind. After mounting a turbine it does not need to be fueled or connected to power to continue working. This lowers the overall cost of maintaining large-scale wind farms.

Clean source of energy


Wind energy does not contribute to global warming and climate change by producing greenhouse gases during energy generation because it does not rely on fossil fuels to power the turbines. Wind energy only emits greenhouse gases indirectly during the production and transportation of wind turbines, as well as during the installation process. In the long term, this amounts to very low emissions.

Offshore Wind Farm
Offshore Wind Farm

Doesn’t Affect Farming Operations


Wind turbines can be built on pre-existing farmland. Energy providers can pay farm owners to build wind farms on their land through contracts or leases. As wind turbine footprints take up very little ground space, it won’t interfere with the farm’s produce. Offshore windfarms helps in saving space.

Reduces our dependence on fossil fuels


Energy from fossil fuel not only contributes to climate change, but it will also run out one day. There is an unlimited supply of wind as long as the sun heats the planet.

Wind Energy Disadvantages

Although wind energy is a renewable and environmentally friendly source of energy, it still has drawbacks and limitations.

Harms wildlife

Wind turbines can harm wildlife. The blades of wind turbines can harm or kill the flying birds and bats that come into contact with the blades. Aside from wildlife that soars through the air, noise pollution from spinning blades may have an impact on animals on the ground.

Noisy

Since wind turbines can be rather noisy, we can mount them only in remote places where few people dwell. Noise isn’t a concern in the case of offshore turbines. As technology advances, we have newer designs that lessen noise issues and offer a much quieter presence.

Expensive Initial Investment

Wind turbines are gigantic structures that are often hundreds of feet tall and demand significant initial investment. The installation of wind turbines in rural areas necessitates additional investment in underground lines to transport power to more populated areas such as towns and cities.

Unreliable and Unpredictable


Wind energy is subject to intermittency, which is a disturbance due to the wind’s inconsistency. Since wind can blow at different speeds, it’s difficult to anticipate how much energy it can deliver at any particular time. This means that suppliers and towns must have an energy reserve or alternate sources of power. This is in the event that the winds stop blowing for an extended period of time.

Wind Energy Future

Wind energy can assist in the production of green hydrogen and green ammonia which are future fuels. This will hasten our rate of energy transformation and reduce the necessity for large-scale, high-cost oil exports.

When we combine all benefits of wind energy and solar energy, we are on our way to realising the full potential of renewable energy through wind-solar hybrid projects. These initiatives will boost efficiency while also ensuring power continuity and consistency. Check out our blog Solar Energy- Definition, Advantages and Future to know more about solar energy.

Shall we wrap up?

Conclusion

Wind is caused by the uneven heating of Earth by Solar radiation. Hence wind energy is an indirect form of solar energy. By tapping into this huge energy source alone or in conjunction with solar energy we can reduce our dependence on fossil fuels and save ourselves from the impending energy crisis. Let’s switch to wind energy for a better tomorrow.

Happy Learning.