Solar-powered photovoltaic (PV) panels convert the sun's rays into electricity by exciting electrons in silicon cells using the photons of light from the sun. This electricity can then be used to supply renewable energy to your home or business. Light striking a silicon semiconductor causes electrons to flow, creating electricity. Solar power generating systems take advantage of this property to convert sunlight directly into electrical energy. 

Plants trap the solar energy and convert it into chemical energy by the process of photosynthesis.This chemical energy in the form of carbohydrates or sugar is used as food.

Solar energy is the renewable source of energy which is essential for all living beings.All plant life needs solar energy to prepare their food by photosynthesis and the animal life is dependent on plants directly or indirectly.So it is the prime source of energy.

The Sun is the primary source of energy for Earth's climate system is the first of seven Essential Principles of Climate Sciences. Principle 1 sets the stage for understanding Earth's climate system and energy balance. The Sun warms the planet, drives the hydrologic cycle, and makes life on Earth possible.Each second, more than four million tonnes of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation.

The forms of energy from the sun are heat and light.

Hydrogen fuel can provide motive power for liquid-propellant rockets, cars, boats and airplanes, portable fuel cell applications or stationary fuel cell applications, which can power an electric motor. The problems of using hydrogen fuel in cars arise from the fact that hydrogen is difficult to store in either a high pressure tank or a cryogenic tank.

Simple things like switching off fans and lights when not in use, using maximum daylight, walking instead of driving for short distances, using CFL instead of traditional bulbs, proper insulation for leakage of energy can go a long way in saving energy.

The methods of controlling hydrocarbons from production are

A strike by unions in an oil producing firm can definitely cause an energy crisis.

There are many advantages of renewable energy but the only disadvantage is that proper equipment for their conversion are not easily available. Either they are very costly or not easily available.

Less usage of automobiles and controlling population he following measures can help in controlling hydro carbon pollution
Hence option C is the correct answer.

Hydrogen gas is cleaner fuel than $CNG$ as $CNG$ contains hydrocarbons which in turn contains carbon and it is a form of pollutant present in $CNG.$  But hydrogen is waste-free. The fusion of hydrogen does not produce any waste and therefore it is cleaner than $CNG.$

Sink acts as a medium which retains and interacts with a pollutant.

Fuels extracted from plants and crops are known as biofuels. They not only help a struggling economy by providing jobs but also helps in reducing greenhouse gases up to much extent by emitting less pollution. 

Cooking oil or Vegetable oil can be used as an alternative fuel in diesel engines and in heating oil burners. When vegetable oil is used directly as a fuel, in either modified or unmodified equipment, it is referred to as straight vegetable oil (SVO) or pure plant oil (PPO). Conventional diesel engines can be modified to help ensure that the viscosity of the vegetable oil is low enough to allow proper atomization of the fuel. This prevents incomplete combustion, which would damage the engine by causing a build-up of carbon. Straight vegetable oil can also be blended with conventional diesel or processed into biodiesel or bioliquids for use under a wider range of conditions.

Hence, the correct option is $D$

Biomass is an organic material that comes from plants and animals and it is a renewable source of energy.

The ultimate source of energy is Sun because it is continuously providing us with energy and is the source of all other energies like light energy, heat energy, etc.

In hydropower plant, the potential energy possessed by the stored water is converted into electricity with help of a turbine of an electric generator.

$\Rightarrow$  Bio-fuels are designed to replace gasoline, diesel fuel and coal, which are called “fossil fuels” because they are made from animals and plants that died millions of years ago. 

Conventional energy directly mean the energy source which is fixed in nature like oil, gas and coal. In other words conventional energy is also termed as non-renewable energy sources. Their use leads to increased greenhouse gas emissions and other environmental damage. Natural gas is a fossil fuel used as a source of energy for heating, cooking, and electricity generation. It is also used as fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals. It is a non-renewable resource.

Liquefied petroleum gas or liquid petroleum gas (LPG or LP gas), also referred to as simply propane or butane, are flammable mixtures of hydrocarbon gases used as fuel in heating appliances, cooking equipment, and vehicles. The percentage of butane is around 70% and that of propane is around 30%.

Liquefied petroleum gas or liquid petroleum gas (LPG or LP gas), also referred to as simply propane or butane, are flammable mixtures of hydrocarbon gases used as fuel in heating appliances, cooking equipment, and vehicles. The percentage of butane is around 70% and that of propane is around 30%.

Hydro and wind energy plants are non-polluting sources of energy as they do not emit any kind of harmful substances.

Power generated in a windmill depends on the velocity of the wind. More is the velocity $\longrightarrow$ more will be the velocity of the windmills thereby generating more power.

Sewer gases may include hydrogen sulphide, ammonia, $CO,SO _2,NO$, etc. Improper disposal of petroleum products such as gasoline and mineral gas spirits contribute to sewer gas hazards.

Biogas is produced by anaerobic degradation of biological materials such as food wastes, animal and plant wastes. Biogas is produced when organic matter decomposes without oxygen in a process which is called anaerobic decomposition. Biogas consists mainly of methane, carbon dioxide and small amounts of impurities/residues.

So the residue from biogas plant serves as organic manure.

Nuclear fusion is a process where two or more nuclei combine to form an element with a higher atomic number (more protons in the nucleus). Fusion is the reverse process of nuclear fission.

The main component of bio gas is methane.
Methane is also the important constituent (95%) of natural gas. Methane has high heat of combustion. Hence, it is used as fuel.
$CH _4 + 2O _2 \rightarrow CO _2 + 2H _2O + heat$

Hydrogen is both a storage and transport energy medium that can connect the energy source to the energy consumer.

Pure hydrogen is the smallest element and some of it will inevitably escape from any known container or pipe in micro amounts. It causes the metal to become brittle, suggesting metal pipes may not be ideal for hydrogen transport.

An electricity shortage is felt most acutely in heating, cooking, and water supply. Therefore, a sustained energy crisis may become a humanitarian crisis.

If an energy shortage is prolonged a crisis management phase is enforced by authorities. Energy audits may be conducted to monitor usage. Various curfews with the intention of increasing energy conservation may be initiated to reduce consumption.

Wars and attacks do not solve the problem of energy crisis, on the contrary they destroy the potential sources of energy.

There are some downsides of using hydrogen as a fuel :
1.Few filling stations sell hydrogen.
2.Hydrogen must be compressed and liquefied, and then stored in tough, insulated fuel tanks.
3.Atmospheric pollution may be generated during the production of hydrogen.
4.Hydrogen fuel cells do not work at very low temperatures, and they may also require a platinum catalyst (platinum is expensive and prone to contamination by impurities).

Less usage of automobiles and controlling population he following measures can help in controlling hydro carbon pollution
Hence option C is the correct answer.

Hydrogen is both powerful and efficient. It is enough to provide power for powerful machines such as spaceships. Also, it is environmentally friendly and is a much safer choice compared to other fuel sources. Hydrogen is three times as powerful as gasoline and other fossil fuels. This means that it can accomplish more with less.

Renewable sources are a bit costly as compared to fossil fuels but they are eco-friendly.

Energy simulation software can be used by big corporates and corporations to redesign building unit and reduce running business energy cost. Engineers, architects and designers could use this design to come with most energy efficient building and reduce carbon footprint. Hence it cannot be the reason for energy crisis, rather it is the solution to energy crisis.

Both developed and developing countries should adopt a common stand on climate change. They should focus on reducing greenhouse gas emissions through an effective cross border mechanism. With current population growth and over consumption of resources, the consequences of global warming and climate change cannot be ruled out. Both developed and developing countries must focus on emissions cuts to cut their emission levels to half from current levels by 2050.

Tax hikes, strikes, military coup, political events, severe hot summers or cold winters can cause sudden increase in demand of energy and can choke supply. A strike by unions in an oil producing firm can definitely cause an energy crisis. Hence tax hikes are the reason for the increase in energy crisis not the solution.

In few countries, there is a significant delay in commissioning of new power plants that can fill the gap between demand and supply of energy. The result is that old plants come under huge stress to meet the daily demand for power. When supply doesnt matches demand, it results in load shedding and breakdown.

Demand for natural resources has in the past been correlated with economic growth, but there are more factors at play than simple economics. Population change alone does also not lead to more demands for natural resources – although both play a part. Factors such as income growth, environmental change, advances in technology and price pressures all have a part to play.

The Pollutant Standards Index, or PSI, is a type of air quality index, which is a number used to indicate the level of pollutants in air. The PSI is reported as a number on a scale of 0 to 500. The index figures enable the public to determine whether the air pollution levels in a particular location are good, unhealthy, hazardous or worse.

Tidal power is taken from the Earth's oceanic tides. Tidal forces are periodic variations in gravitational attraction exerted by celestial bodies. These forces create corresponding motions or currents in the world's oceans. Due to the strong attraction to the oceans, a bulge in the water level is created, causing a temporary increase in sea level. When the sea level is raised, water from the middle of the ocean is forced to move toward the shorelines, creating a tide. Because the Earth's tides are ultimately due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is practically inexhaustible and classified as a renewable energy resource.

Biodegradable pollutants:

Those pollutants which can be broken down into simpler, harmless, substances in nature in due course of time (by the action of micro-organisms like certain bacteria) are called biodegradable pollutants. Domestic wastes (garbage), urine, faecal matter, sewage, agriculture residues, paper, wood, cloth, cattle dung, animal bones, leather, wool, vegetable stuff or plants are biodegradable pollutants.

Non-biodegradable pollutants:

Those pollutants which cannot be broken down into simpler, harmless substances in nature, are called non-biodegradable pollutants. DDT, plastics, polythene, bags, insecticides, pesticides, mercury, lead, arsenic, metal articles like aluminum cans, synthetic fibres, glass objects, iron products and silver foils are non-biodegradable pollutants.

Cleanliness and less use of insecticides, proper disposal of organic wastes, sewage and industrial effluents, broder roads and shifting of factories out of the residential areas all help in reduction of pollution. 

Environmental pollution has following effects:

1. Effects on Humans: The effects of environmental pollution on humans are mainly physical, but can also turn into neuro-affections in the long term.

2. Effects on Animals: Environmental pollution mainly affects animal by causing harm to their living environment, making it toxic for them to live in

3. Effects on Plants: As for animals, plants, and especially trees, can be destroyed by acid rains (and this will also have a negative effect on animals as well, as their natural environment will be modified), ozone in the lower atmosphere block the plant respiration, and harmful pollutants can be absorbed from the water or soil.

4. Effects on the Ecosystem: In short, environmental pollution, almost exclusively created by human activities, has a negative effect on the ecosystem, destroying crucial layers of it and causing an even more negative effect on the upper layers.

Nuclear fallout, or simply fallout, is the residual radioactive material propelled into the upper atmosphere following a nuclear blast or a nuclear reaction conducted in an unshielded facility, so called because it "falls out" of the sky after the explosion and the shock wave have passed. While deforestation, soil erosion and increasing deserts can be controlled, nuclear fallout causes genetic mutation in humans and destruction that cannot be controlled or cured.

People all across the globe use these energy sources to generate electricity for homes, business, factories and schools. We use this energy to light bulb, run computer, refrigerators, washing machines and air conditioners etc. We use energy to run our cars and trucks. Both the gasoline used in our cars, and the diesel fuel used in our trucks are made from oil. Since, renewable sources are not used on much wider scale and use of Non-renewable sources cause pollution to the environment and may extinct if used in a hazardous manner, so the need of the hour is to conserve these resources and use them in an efficient manner to minimize the wastage and making this planet a better place to live in.

Petroleum and natural gas are formed by the anaerobic decomposition of remains of organisms including phytoplankton and zooplankton that settled to the sea (or lake) bottom in large quantities under anoxic conditions, millions of years ago. Over geological time, this organic matter, mixed with mud, got buried under heavy layers of sediment. The resulting high levels of heat and pressure caused the organic matter to chemically alter, first into a waxy material known as kerogen which is found in oil shales, and then with more heat into liquid and gaseous hydrocarbons in a process known as catagenesis. Despite these heat driven transformations (which may increase the energy density compared to typical organic matter), the embedded energy is still photosynthetic in origin.

There is a wide range of organic, or hydrocarbon, compounds in any given fuel mixture. The specific mixture of hydrocarbons gives a fuel its characteristic properties, such as boiling point, melting point, density, viscosity, etc. Some fuels like natural gas, for instance, contain only very low boiling, gaseous components. Others such as gasoline or diesel contain much higher boiling components.

Otto cycle is the typical cycle for most of the cars internal combustion engines that work using gasoline as a fuel. To reduce pollution LPG is used as a source of clean fuel. Blast furnace gas may be combined with natural gas or coke oven gas before combustion. Hence all of the above are used for internal combustion of engines.

Compressed natural gas (CNG) can now be used as a fuel for gas-fueled captive power plants. Natural gas as fuel source has a significant number of benefits versus diesel including reduced emissions and reduced fuel costs.

Natural gas can be used to generate electricity in a variety of ways. The most basic natural gas-fired electric generation consists of a steam generation unit, where fossil fuels are burned in a boiler to heat water and produce steam that then turns a turbine to generate electricity. It is a non-renewable resource. Natural gas is found in deep underground rock formations or associated with other hydrocarbon reservoirs in coal beds and as methane clathrates. Petroleum is another resource and fossil fuel found in close proximity to and with natural gas.

Compressed Natural gas is the cleanest of all the fossil fuels, composed primarily of methane. The main products of the combustion of natural gas are carbon dioxide & water vapor, which are the same compounds we exhale when we breathe.  Coal & oil are composed of much more complex molecules, with a higher carbon ratio & higher nitrogen & sulfur contents. This means that when combusted, coal & oil release higher levels of harmful emissions, including a higher ratio of carbon emissions, nitrogen oxides & sulfur dioxide. Coal & fuel oil also release ash particles into the environment, substances that do not burn but instead are carried into the atmosphere & contribute to pollution.

The combustion of natural gas, on the other hand, releases very small amounts of sulfur dioxide & nitrogen oxides, virtually no ash or particulate matter & lower levels of carbon dioxide, carbon monoxide & other reactive hydrocarbons

Compressed Natural Gas happens to be a very viable alternative to traditional fuels particularly for use in the automobile industry. Being low in pollutants, high in calorific value and heat yield, economical and available in abundance globally, CNG is the perfect alternative for most.

Secondly, CNG is environment friendly as it reduces vehicular exhaust emissions significantly. Carbon Monoxide emissions are reduced to a maximum of 90 per cent and Hydrocarbon emissions by 60 per cent as compared to vehicles that use Petrol. Carbon Dioxide emissions, a cause for global warming, are also reduced significantly by 10 per cent.

Non-luminous flames are the ones that burn blue. These flames have access to as much oxygen as they could possibly use, so they can burn very efficiently. All of the carbon that gets used can be turned into carbon dioxide, so there's actually no soot. Complete combustion of LPG takes place. Hence, it burns with a blue flame.

Liquefied Petroleum Gas is considered as cleanest fuel because of the following reasons:

1. LPG has a high calorific value. The calorific value of LPG is about 50 KJ/g.
2. It is very neat and clean domestic fuel. LPG burns with a blue smokeless flame and leaves no ash behind. So, it does not cause any pollution. Therefore, LPG is a clean fuel.
3. It does not produce any poisonous gases on combustion.
4. LPG is easy to handle and convenient to store.
5. LPG is easy to handle and can be ignited almost instantaneously.

CNG is stored in pressurized vessels or spheres. They are gaseous in nature at STP. For it to be transported and used it is liquefied and kept in pressurized tanks. 

Energy can neither be created nor destroyed, but it does change its form. And not all forms of energy are usable and it gets dissipated as heat energy and sound energy. The energy that is wasted cannot be recovered. Moreover, the current sources or energy such as fuels are non-renewable in nature and are rapidly consumed. That is why we are facing energy crisis.

The Complete Combustion of Natural Gas yields carbon dioxide and water. Complete combustion happens when the hydrocarbon burns in an excess of air. An excess of air means that there is more than enough oxygen to cause all of the carbon to turn into carbon dioxide.

The methane gas burns with a clear blue flame.

methane + oxygen  $\rightarrow$ carbon dioxide + water + energy

$CH _4(g) +  2O _2(g)   \rightarrow  CO _2(g) +  2H _2O(l)$           

The reaction is exothermic. The heat released from burning natural gas is used for central heating and to generate electricity.

CNG is made by compressing natural gas which is mainly composed of methane, to less than 1 percent of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 MPa, usually in cylindrical or spherical shapes.

Vadodara Gas Limited operates nine CNG stations in Vadodara and dispensing more than 65,000 kg/day CNG, catering to the consumers of automobile sector comprising Buses, Cars and Auto-rickshaws. The CNG network in the City of Vadodara includes 2-Mother Stations, 1-On-line Station and 6-Daughter Booster Stations and 13 Km Steel Pipelines.

Biodiesel is produced in a pure form (referred to as “B100”or “neat biodiesel”) and is typically blended with petroleum-based diesel fuel. Such biodiesel blends are designated as BXX, where XX represents the percentage by volume of pure biodiesel contained in the blend (e.g.,“B5,” “B20”).

Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffin including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes). The average chemical formula for common diesel fuel is $C _{12}H _{24}$, ranging approximately from $C _{10}H _{20} ....... C _{15}H _{28}$.

Typically, emissions of nitrogen oxides are either slightly reduced or slightly increased depending on the duty cycle of the engine and testing methods used. Increases in NOx can be effectively eliminated with the use of normal mechanical remediation techniques (e.g. catalysts or timing changes). Research also documents the fact that the ozone forming potential of the hydrocarbon emissions of pure biodiesel is nearly 50% less than that of petroleum fuel. Pure biodiesel does not contain sulphur and therefore reduces sulphur dioxide exhaust from diesel engines to virtually zero.

Usually derived from vegetable oils - soy is very popular these days, but animal fats can also be used - biodiesel is made through a chemical process called transesterification which essentially splits the oil into two parts: alkyl esters and glycerine; the esters are the fuel, while the leftover glycerine is often the byproduct.

Biomass feedstocks are the plant and algal materials used to derive fuels like ethanol, butanol, biodiesel, and other hydrocarbon fuels. Examples of biomass feedstocks include corn starch, sugarcane juice, soyabean, crop residues such as corn stover and sugarcane bagasse, purpose-grown grass crops, and woody plants.

Biodiesel blend is a mixer of methyl or ethyl esters derived from a broad variety of renewable sources such as vegetable oil, animal fat and recycled cooking oil. These esters are oxygenated organic compounds that can be used in compression ignition engines. Blend of 20% to 80 % with petroleum diesel significantly reduces carcinogenic emissions and gases that contribute to global warming. It can be used as a 20% blend in most diesel equipment with no or only minor modifications. B20 is the most commonly used biodiesel blend in the United States because it provides a good balance between material compatibility, cold weather operability, performance, emission benefits and costs. 

Biodiesel is a renewable alternative fuel created from vegetable oils, animal fats and greases through a chemical process. The chemical process involves reaction of natural oils with an alcohol in the presence of a catalyst (usually sodium hydroxide [$NaOH$] or potassium hydroxide [$KOH$] and then refining the mixture to create molecules which can be easily burned in a diesel engine.

The following is/are true for hydrogen as the future fuel.
Efforts are being taken to reduce the cost of production of hydrogen.
Better and safer methods of transportation and storage of hydrogen are being worked out.
If these problems are solved, hydrogen will prove to be an ideal fuel not only for rockets but also for vehicles and domestic use.

Sewer gases may include hydrogen sulfide, ammonia, methane, esters, carbon monoxide, sulfur dioxide and nitrogen oxides.
Sewer gas is a generic name for the collection of gases and airborne agents
that often accompany sewage and the natural processes and reactions associated with sewage processing and the decomposition of organic materials.

Sewer gas is a complex mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage. Sewer gases may include hydrogen sulfide, ammonia, methane, esters, carbon monoxide, sulfur dioxide and nitrogen oxides.

The following are the advantages of using hydrogen as an automobile fuel.
The amount of energy released per unit weight of the fuel is very high.
The combustion hydrogen does not produce polluting emissions of CO, $CO _2$, oxides of nitrogen, and sulphur, aldehydes etc. Here, combustion product of hydrogen is water with few traces of nitrogen oxides. So no pollution is caused.
The technology required for use of hydrogen fuel is simple and cost effective.
The fuel cells using catalytic combustion of hydrogen have efficiency of 70-80 percent.

Molasses is a factory waste from sugar industry. It does not contain any traces of methane. So, methane is not obtained from molasses.

Hydrogen gas is considered as the cleanest fuel because when hydrogen burns in air, it produces nothing but water vapour.

Wars between countries can also hamper supply of energy specially if it happens in Middle East countries like Saudi Arabia, Iraq, Iran, Kuwait, UAE or Qatar. Thats what happened during 1990 Gulf war when price of oil reached its peak causing global shortages and created major problem for energy consumers.

Higher the methane content, higher the calorific value. Pure $CH _4$ has a Gross Calorific Value of 39.8 $MJ/m^3$. the rate of combustion of biogas is quite high as it is produced by anaerobic decomposition of animal and plant waste.
It does not leave any ash behind after burning as cow dung and other organic matter is used in the preparation of biogas.