Unit 2

Question Bank

Question 1) What is black carbon and how does it cause global warming?

Answer 1)

Black carbon (BC) is tiny particles of carbon released as a result of the incomplete combustion of fossil fuels, biofuels and biomass. These particles are extremely small, ranging from 10 µm (micrometers, PM10), the size of a single bacterium to less than 2.5 µm (PM2.5), one thirtieth the width of a human hair and small enough to pass through the walls of the human lung and into the bloodstream.

Although BC – think of the plume of smoke from a chimney or a fire – falls out of the lower atmosphere in days, while it is suspended in the air, it absorbs the sun’s heat millions of times more effectively than CO2. When wind carries BC over snow, glaciers or ice caps where it falls out onto the white, normally reflective surface, it is particularly damaging because it contributes directly to melting. Overall, BC is considered the second biggest contributor to global warming after CO2.

Question 2) What is Global Warming?

Answer 2)

Global warming is the slow increase in the average temperature of the earth’s atmosphere because an increased amount of the energy (heat) striking the earth from the sun is being trapped in the atmosphere and not radiated out into space. The earth’s atmosphere has always acted like a greenhouse to capture the sun’s heat, ensuring that the earth has enjoyed temperatures that permitted the emergence of life forms as we know them, including humans. Without our atmospheric greenhouse the earth would be very cold. Global warming, however, is the equivalent of a greenhouse with high efficiency reflective glass installed the wrong way around. Ionically, the best evidence of this may come from a terrible cooling event that took place some 1,500 years ago. Two massive volcanic eruptions, one year after another placed so much black dust into the upper atmosphere that little sunlight could penetrate. Temperatures plummeted. Crops failed. People died of starvation and the Black Death started its march. As the dust slowly fell to earth, the sun was again able to warn the world and life returned to normal. Today, we have the opposite problem. Today, the problem is not that too little sun warmth is reaching the earth, but that too much is being trapped in our atmosphere.

So much heat is being kept inside greenhouse earth that the temperature of the earth is going up faster than at any previous time in history.

Question 3) What is Climate Change?

Answer 3) Climate change refers to significant, long-term changes in the global climate.

The global climate is the connected system of sun, earth and oceans, wind, rain and snow, forests, deserts and savannahs’, and everything people do, too. The climate of a place, says New York, can be described as its rainfall, changing temperatures during the year and so on.

But the global climate is more than the “average” of the climates of specific places.

A description of the global climate includes how, for example, the rising temperature of the Pacific feeds typhoons which blow harder, drop more rain and cause more damage, but also shifts global ocean currents that melt Antarctica ice which slowly makes sea level rise until New York will be under water.

It is this systemic connectedness that makes global climate change so important and so complicated.

Question 4) Are the ozone hole and global warming related?

Answer 4) The ozone hole and global warming are not the same thing, and neither is the main cause of the other. The ozone hole is an area in the stratosphere above Antarctica where chlorine and bromine gases from human-produced chlorofluorocarbons (CFCs) and halons have destroyed ozone molecules. Global warming is the rise in average global surface temperature caused primarily by the build-up of human-produced greenhouses gases, mostly carbon dioxide and methane, which trap heat in the lower levels of the atmosphere.

There are some connections between the two phenomena.

For example, the CFCs that destroy ozone are also potent greenhouse gases, though they are present in such small concentrations in the atmosphere (several hundred parts per trillion, compared to several hundred parts per million for carbon dioxide) that they are considered a minor player in greenhouse warming. CFCs account for about 13% of the total energy absorbed by human-produced greenhouse gases.

The ozone hole itself has a minor cooling effect (about 2 percent of the warming effect of greenhouses gases) because ozone in the stratosphere absorbs heat radiated to space by gases in a lower layer of Earth’s atmosphere (the upper troposphere). The loss of ozone means slightly more heat can escape into space from that region.

Global warming is also predicted to have a modest impact on the Antarctic ozone hole. The chlorine gases in the lower stratosphere interact with tiny cloud particles that form at extremely cold temperatures — below -80 degrees Celsius (-112 degrees Fahrenheit). While greenhouse gases absorb heat at relatively low altitudes and warm the surface, they actually cool the stratosphere. Near the South Pole, this cooling of the stratosphere results in an increase in polar stratospheric clouds, increasing the efficiency of chlorine release into reactive forms that can rapidly deplete ozone.

Question 5) What are the uses of oil in fossil fuel?

Answer 5) Uses of oil: Crude oil or petroleum is also called as “black gold”. There are various uses of petroleum. It is used in the generation of electricity, used in transportation as fuel for automobiles and jets. The by-product of oil is used to produce chemicals, plastics, lubricants, tars, waxes, medicines etc. Also, many of the fertilizers, as well as pesticides, are made from either oil or its by product.

Question 6) What is the Uses of coal?

Answer 6)

Coal is a solid state fossil fuel. It consists of five elements. They are sulphur, nitrogen, hydrogen, carbon and oxygen. Three different types of coal with different energy properties are anthracite, bituminous and lignite. Anthracite is hard with more carbon than the other two and has the highest energy. Coal could exist for 200 years more. It is mostly extracted from the mines. Coal use has almost doubled since the 20th century. Many countries cannot afford natural gas or oil as they are expensive, and so they depend on coal for energy. It is used in the generation of electricity. Also, used in electrical utilities, and products like dyes, aspirins, soap, fibres, plastics and solvents have coal or coal by product. It is used in steel industry, pharmaceutical industry, cement manufacture, manufacturing of paper etc.

Question 7) What is the Uses of natural gas?

Answer 7)

It is a gaseous fuel and primarily consists of methane. It is much cleaner than oil and coal. It is used in air conditioning, cooking appliance like fuel stoves and heat homes and buildings, heating water etc. It also provides electricity and is used in industries like steel foundries, glass foundries other manufacturing, aluminium smelters. It also produces paints, fertilizers, plastics and dyes. It is also used in transportation as CNG or LNG. These were some fossil fuels and their uses.

Question 8) Explain production of nuclear fuel?

Answer 8)

Fuel fabrication plants are facilities that convert enriched uranium into fuel for nuclear reactors. For light water reactors, uranium is received from an enrichment plant in solid form. It is then converted into a gas and chemically converted into a uranium dioxide powder. This powder is then pressed into pellets and packed into fuel assemblies. A mixed oxide fuel can also be created when the uranium powder is packed along with plutonium oxide. The hazards present at fuel fabrication facilities mainly chemical and radiological are similar to the hazards at enrichment plants. These facilities generally pose a low risk to the public.

Question 9) Explain Photovoltaic solar energy?

Answer 9)  A common way for property owners to take advantage of solar energy is with a photovoltaic (PV) solar system. With a solar PV system, solar panels convert sunlight right into electricity that can be used immediately, stored in a solar battery, or sent to the electric grid for credits on your electric bill.

Solar panels convert solar energy into usable electricity through a process known as the photovoltaic effect. Incoming sunlight strikes a semiconductor material (typically silicon) and knocks electrons loose, setting them in motion and generating an electric current that can be captured with wiring. This current is known as direct current (DC) electricity and must be converted to alternating current (AC) electricity using a solar inverter. This conversion is necessary because the U.S. Electric grid operates using AC electricity, as do most household electric appliances. Solar energy can be captured at many scales using photovoltaic, and installing solar panels is a smart way to save money on your electric bill while reducing your dependence on non-renewable fossil fuels. Large companies and electric utilities can also benefit from photovoltaic solar energy generation by installing large solar arrays that can power company operations or supply energy to the electric grid.

Question 10) Explain Solar thermal energy?

Answer 10)

A second way to use solar energy is to capture the heat from solar radiation directly and use that heat in a variety of ways. Solar thermal energy has a broader range of uses than a photovoltaic system, but using solar thermal energy for electricity generation at small scales is not as practical as using photovoltaic.

There are three general types of solar thermal energy used: low-temperature, used for heating and cooling; mid-temperature, used for heating water; and high-temperature, used for electrical power generation.

Low-temperature solar thermal energy systems involve heating and cooling air as a means of climate control. An example of this type of solar energy usage is in passive solar building design. In properties built for passive solar energy use, the sun’s rays are allowed into a living space to heat an area and blocked when the area needs to be cooled.

Mid-temperature solar thermal energy systems include solar hot water heating systems. In a solar hot water setup, heat from the sun is captured by collectors on your rooftop. This heat is then transferred to the water running through your home’s piping so you don’t have to rely on traditional water heating methods, such as water heaters powered with oil or gas.

High-temperature solar thermal energy systems are used for generating electricity on a larger scale. In a solar thermal electricity plant, mirrors focus the sun’s rays on tubes containing a liquid that can hold heat energy well. This heated fluid can then be used to turn water into steam, which then can turn a turbine and generate electricity. This type of technology is often referred to as concentrated solar power.