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Frequently Asked Questions
- What is “climate change”?
- What is the difference between climate and weather?
- What is the difference between climate change and global warming?
- What is Florida doing to battle the effects of climate change?
- What are greenhouse gases?
- Where do Florida’s greenhouse gas emissions come from?
- What is the greenhouse effect?
- How have greenhouse gas levels in our atmosphere changed since the Industrial Revolution?
- Does ozone layer depletion have anything to do with climate change?
- Does El Nino have anything to do with climate change?
- Are human activities responsible for the warming climate?
- Can changes in climate be attributed to natural factors?
- How do scientists predict future climate?
- How much is the climate expected to warm?
- Will the climate change uniformly across the globe?
- What is the Intergovernmental Panel on Climate Change (IPCC)?
- What is bioenergy and how and where can I use it?
- How can we get electricity from the sun?
- What is photovoltaics (solar electricity), or “PV”?
- How does a solar water-heating system work?
- What is concentrating solar power?
- What is geothermal energy? How can it be used?
- What is wind energy? How can it be harnessed into electricity?
- How does hydropower work?
- What are some effects of hydropower?
- What are the materials used in Silicon PV Cell Production?
1. What is “climate change”?
Climate change refers to any significant change in measures of climate – such as temperature, precipitation, or wind – lasting for an extended period (decades or longer). Climate change stems from:
Scientists are pointing to evidence of climate change from direct measurements of rising temperatures of the Earth’s surface and the ocean’s subsurface; increases in average sea levels; and shrinking glaciers. Experts believe that the rising temperatures in recent decades can be primarily attributed to human activities which have led to increased atmospheric concentrations of a number of greenhouse gases.
2. What is the difference between climate and weather?
The main distinction between climate and weather is the time frame. Weather describes short-term atmospheric conditions in a specific place, such as a sunny day in Florida or a snowstorm in Wisconsin. Climate, on the other hand, refers to average atmospheric conditions over an extended period of time, such as decades or centuries. Florida and Wisconsin have very different climates, even though their weather can possibly be similar on any one day.
3. What is the difference between climate change and global warming?
The term climate change is often used interchangeably with the term global warming, but according to the National Academy of Sciences, “the phrase ‘climate change’ is growing in preferred use to ‘global warming’ because it helps convey that there are [other] changes in addition to rising temperatures.” Climate change refers to any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). Global warming is an average increase in the temperature of the atmosphere near the Earth’s surface and in the troposphere, which can contribute to changes in global climate patterns. Global warming and climate change can be caused by a variety of factors, both natural and human-induced.
4. What is Florida doing to battle the effects of climate change?
On July 13, 2007, FL Governor signed a groundbreaking set of Executive Orders at the Serve to Preserve Florida Summit on Global Climate Change that put into place a new direction for Florida’s energy future. The three Executive Orders represent the Governor’s commitment to addressing global climate change, a promise to reduce Florida’s greenhouse gases, increase our energy efficiency and pursue more renewable energy sources, such as solar and wind technologies, as well as alternative energy, such as ethanol and hydrogen. In addition, Governor committed to partnering with Germany and the United Kingdom to discuss and promote initiatives that broaden the Kyoto Protocol and reduce the emission of greenhouse gases beyond 2012.
5. What are greenhouse gases?
Greenhouse gases are materials found in the atmosphere that absorb heat energy from the Earth and prevent this heat from escaping into space. Primary greenhouse gases include water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). While these gases occur naturally in the environment, they can create problems when they are at unnaturally high concentrations.
The growing reliance on fossil fuels, rapid global deforestation, and inefficient industrial production have all caused the concentrations of heat-trapping greenhouse gases to increase significantly in our atmosphere. Thus, we are faced with the challenge of controlling these greenhouse gases.
6. Where do Florida’s greenhouse gas emissions come from?
The best hard data we have about Florida greenhouse gas emissions comes for the Energy Information Administration (EIA). Of the total 243.9 million metric tons of energy-related carbon dioxide produced during 2003, the electric power and transportation sectors were responsible for over 90 percent of the emissions.
The electric power industry had emissions of 125.1 million metric tons, equaling 51 percent of the total, and the combustion of motor fuels for all modes of transportation in Florida produced 98.2 million metric tons or 40 percent of the total.
The total greenhouse gas emissions associated with landfills, cement plants, and agriculture ” the other principal sources of emissions in Florida” have not yet been quantified, but a gross estimate would range from 20 to 30 million metric tons.
7. What is the greenhouse effect?
The greenhouse effect is a natural phenomenon that helps regulate the Earth’s temperature. Greenhouse gases (e.g., carbon dioxide, methane, nitrous oxide, chlorofluorocarbons) act like an insulating blanket, trapping solar energy that would otherwise escape into space. Without this natural “greenhouse effect,” temperatures would be about 60ºF lower than they are now, and life as we know it today would not be possible. However, human activities, primarily the burning of fossil fuels and clearing of forests, have enhanced the natural greenhouse effect, causing the Earth’s average temperature to rise.
8. How have greenhouse gas levels in our atmosphere changed since the Industrial Revolution?
Since pre-industrial times, atmospheric concentrations of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) have climbed by over 36 percent, 148 percent, and 18 percent, respectively (see the Recent Atmospheric Change page on EPA’s Climate Change site for more details). Greenhouse gas concentrations in the atmosphere have varied historically as a result of many natural processes (e.g., volcanic activity, changes in temperature, etc). However, since the Industrial Revolution, humans have added a significant amount of greenhouse gases to the atmosphere primarily by burning fossil fuels, cutting down forests, and other activities. Scientists have confirmed that the recent increase in atmospheric greenhouse gas concentrations is primarily due to human activity.
9. Does ozone layer depletion have anything to do with climate change?
Climate change and ozone depletion are two distinct but interrelated issues. Ozone depletion is not a principal cause of climate change and climate change is not a principal cause of ozone depletion. However, ozone-depleting gases — such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and halons — are greenhouse gases that do contribute to climate change. Ozone itself is a greenhouse gas and has an effect on climate. In addition, certain changes in Earth’s climate could affect the future condition of the ozone layer. For example, low temperatures and strong polar winds both affect the extent and severity of winter polar ozone depletion.
10. Does El Nino have anything to do with climate change?
El Nino is the strong warming of the equatorial Pacific Ocean that occurs about every two to seven years. Recent El Nino events have been very strong and have contributed to record-setting temperatures-evidence that El Nino events can warm parts of the Earth. Scientists are now examining how human-induced climate change could affect El Nino.
11. Are human activities responsible for the warming climate?
Careful measurements have confirmed that greenhouse gas emissions are increasing and that human activities (principally, the burning of fossil fuels and changes in land use) are the primary cause. Human activities have caused the atmospheric concentrations of carbon dioxide and methane to be higher today than at any point during the last 650,000 years. Scientists agree it is very likely that most of the global average warming since the mid-20th century is due to human-induced increases in greenhouse gases, rather than to natural causes.
12. Can changes in climate be attributed to natural factors?
Natural variations within the Earth’s climate system can cause small changes over decades to centuries. Larger changes can occur through factors such as gradual changes in Earth’s orbit around the Sun, which are thought to be the key contributors in the comings and goings of past ice ages over many millennia. The Sun’s energy can also vary over time. Large volcanic eruptions and collisions with large meteorites can cool the planet for a few years by spewing out particles that reflect sunlight back out to space. However, while natural variations have altered the climate significantly in the past, it is very unlikely that the changes in climate observed since the mid-20th century can be explained by natural processes alone.
13. How do scientists predict future climate?
Future climate change is predicted principally through the use of climate models. These models are mathematical representations of the climate system, expressed as computer simulations. While scientists are more confident in model estimates for some climate variables (e.g., temperature) than for others (e.g., precipitation), there is significant confidence that climate models provide credible estimates of future climate change. This assurance stems from the fact that climate models are based on accepted physical principles as well as their ability to reproduce observed features of current climate and past climate changes. Still, predicting any event in the future is an uncertain business, and estimates of future climate change are given as projections with a range of uncertainty. The degree of uncertainty is higher for regional and local projections than it is for continents and the Earth as a whole. Models are improving in their ability to simulate regional climates, but scientists are less confident in their predictions at small scales. For more information, visit the State of Knowledge page on EPAâ’s Climate Change site.
Source: NOAA – Climate Modeling
14. How much is the climate expected to warm?
Scientists project an average global temperature increase of 3.2-7.2°F by 2100, and greater warming thereafter. Because human emissions of carbon dioxide and other greenhouse gases continue to climb, and because they remain in the atmosphere for decades to centuries (depending on the gas), weâ’re committing ourselves to a warmer climate in the future. In addition, temperatures will not change uniformly across the globe. In some parts of the globe (e.g., the polar regions) temperatures are expected to rise even faster than the global average, while other regions may warm more slowly than average. For more information, visit the Future Climate Change page on EPA’s Climate Change site.
15. Will the climate change uniformly across the globe?
Climate change will not occur equally across our planet, nor will its impacts be felt equally everywhere. Climate is driven by the interactions among solar heating and the atmosphere, oceans, and land surfaces. Variation in solar and geographic factors will cause regional climates to change at different rates and magnitudes. Further, not all ecosystems and human settlements are equally sensitive to changes in climate. Nations (and regions within nations) vary in their relative vulnerability to changes in temperature, precipitation, and extreme weather events, and in their ability to cope with such changes. For more information, visit the International Impacts page of EPA’s Climate Change site.
16. What is the Intergovernmental Panel on Climate Change (IPCC)?
The IPCC was formed jointly in 1988 by the United Nations Environment Program and the World Meteorological Organization. The IPCC brings together the world’s top scientists in all relevant fields, synthesizes peer-reviewed scientific literature on climate change, and produces authoritative assessments of the current state of knowledge of climate change. It produces periodic reports on scientific, technical, and socio-economic information relevant for the understanding of climate change, its potential impacts, and options for adaptation and mitigation.
17. What is bioenergy and how and where can I use it?
Bioenergy is renewable energy made from any organic material from plants or animals. Sources of bioenergy are called “biomass,” and include agricultural and forestry residues, municipal solid wastes, industrial wastes, and terrestrial and aquatic crops grown solely for energy purposes. Biomass is an attractive petroleum alternative because it is a renewable resource that is more evenly distributed over the Earth’s surface than finite energy sources, and may be exploited using more environmentally friendly technologies. Today, biomass resources are used to generate electricity and power, and to produce liquid transportation fuels, such as ethanol and biodiesel. Ethanol is the most widely used liquid transportation fuel, or biofuel. Currently, a majority of ethanol is made from corn, but new technologies are being developed to make ethanol from a wide range of agricultural and forestry resources. Ethanol may be used as an alternative fuel, for example, in E-85 for flex fuel vehicles, and may also be used as an octane-boosting, pollution-reducing additive to gasoline, such as E-10. E-10 is widely available at gas stations in most parts of the U.S. Although availability of E-85 is more limited, use of E-85 is growing and there are currently more than 7 million vehicles on the road today that can the alternative fuel. For a list of vehicles that use E-85 and the locations of fueling stations, visit the Alternative Fuels and Advanced Vehicles Data Center http://www.eere.energy.gov/afdc/.
18. How can we get electricity from the sun?
When certain semiconducting materials, such as certain kinds of silicon, are exposed to sunlight, they release small amounts of electricity. This process is known as the photoelectric effect. The photoelectric effect refers to the emission, or ejection, of electrons from the surface of a metal in response to light. It is the basic physical process in which a solar electric or photovoltaic (PV) cell converts sunlight to electricity. Source: http://apps1.eere.energy.gov/solar/cfm/faqs
Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy, corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the PV cell (which is actually a semiconductor).
With its newfound energy, the electron escapes from its normal position in an atom of the semiconductor material and becomes part of the current in an electrical circuit. By leaving its position, the electron causes a hole to form. Special electrical properties of the PV cell – a built-in electric field- provide the voltage needed to drive the current through an external load (such as a light bulb).
19. What is Photovoltaics (solar electricity) or PV?
The word itself helps to explain how photovoltaic (PV) or solar electric technologies work. First used in about 1890, the word has two parts: photo, a stem derived from the Greek phos, which means light, and volt, a measurement unit named for Alessandro Volta (1745-1827), a pioneer in the study of electricity. So, photovoltaics could literally be translated as light-electricity. And that’s just what photovoltaic materials and devices do; they convert light energy to electricity, as Edmond Becquerel and others discovered in the 18th Century.
20. How does a solar water-heating system work?
Every solar water-heating system features a solar collector that faces the sun to absorb the sun’s heat energy. This collector can either heat water directly or heat a “working fluid” that’s then used to heat the water. In active solar water-heating systems, a pumping mechanism moves heated water through the building. In passive solar water-heating systems, the water moves by natural convection. In almost all cases, solar water-heating systems work in tandem with conventional gas or electric water-heating systems; the conventional systems operate as needed to ensure a reliable supply of heated water.
There are many types of solar water heaters. Each has strengths to recommend it for specific climates and water conditions. Solar system professionals can help you select the most appropriate system for your area and your needs.
21. What is concentrating solar power?
The real powerhouse in CSP plants is focused sunlight. CSP plants generate electric power by using mirrors to concentrate (focus) the sun’s energy and convert it into high-temperature heat. That heat is then channeled through a conventional generator. The plants consist of two parts: one that collects solar energy and converts it to heat, and another that converts the heat energy to electricity. Within the United States, over 350MW of CSP capacity exists and these plants have been operating reliably for more than 15 years.
CSP systems can be small enough (Stirling systems as small as 10 kilowatts are under development) to help meet a small village’s power needs. (For comparison, a typical U.S. home might require a system generating about 5 to 15 kilowatts to meet most of its power needs, according to some renewable energy experts.) CSP systems can also be much larger, generating up to 100 megawatts of power for use in utility-grid-connected applications. Some CSP systems include thermal storage to provide power at night or when it’s cloudy. Others are combined with natural gas systems in hybrid power plants that provide power on demand.
The amount of power generated by a concentrating solar power plant depends on the amount of direct sunlight at the site. CSP technologies make use of only direct-beam (rather than diffuse) sunlight.
Today’s CSP systems can convert solar energy to electricity more efficiently than ever before. Utility-scale trough plants are the lowest cost solar energy available today and further cost reductions are anticipated to make CSP competitive with conventional power plants within a decade. So, CSP is a very good renewable energy technology to use in the southwestern United States as well as in other sunny regions around the world.
22. What is geothermal energy? How can it be used?
Geothermal energy is the heat contained within the earth’a clean, reliable, and renewable energy. Geothermal energy heats water that has seeped into underground reservoirs. These reservoirs can be tapped for a variety of uses, depending on the temperature of the water. The energy from high-temperature reservoirs (225°-600°F) can be used to produce electricity. It can be used as an energy-efficient heating and cooling alternative for buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk.
In the United States, geothermal energy has been used to generate electricity on a large scale since 1960. Through research and development, geothermal power is becoming more cost-effective and competitive with fossil fuels.
There are currently three types of geothermal power plants: dry steam, flash steam, and binary cycle. Current drilling technology limits the development of geothermal resources to relatively shallow water- or steam-filled reservoirs, most of which are found in the western part of the United States. But researchers are developing new technologies for capturing the heat in deeper, “dry” rocks, which would support drilling almost anywhere.
23. What is wind energy? How can it be harnessed into electricity?
Wind is harnessed and converted into electricity using turbines called wind turbines. There are several varieties of turbines including horizontal axis turbine and vertical axis turbines. The amount of electricity that a turbine produces depends on its size and the speed of the wind. Air passes by both sides of the turbine blades. A difference in pressure causes the blades to spin around the center of the turbine at about 18 RPM. The blades are attached to a rotor shaft which is connected to a series of gears that rotates about 100 times faster than the turbine blades. As the shaft is connected to a generator, it turns the generator and produces electricity.
Wind energy technologies can be used as stand-alone applications, connected to a utility power grid, or even combined with a photovoltaic system. For utility-scale sources of wind energy, a large number of turbines are usually built close together to form a wind farm that provides grid power. Several electricity providers use wind farms to supply power to their customers. Stand-alone turbines are typically used for water pumping or communications. However, homeowners and farmers in windy areas can also use small wind systems to generate electricity.
24. How does hydropower work?
Hydropower is using water to power machinery or make electricity. Water constantly moves through a vast global cycle, evaporating from lakes and oceans, forming clouds, precipitating as rain or snow, and then flowing back down to the ocean. The energy of this water cycle, which is driven by the sun, can be tapped to produce electricity or for mechanical tasks like grinding grain. Hydropower uses a fuel “water” that is not reduced or used up in the process. Because the water cycle is an endless, constantly recharging system, hydropower is considered a renewable energy. Hydroelectric facilities are all powered by the kinetic energy of flowing water as it moves downstream. Turbines and generators convert the energy into electricity, which is then fed into the electrical grid to be used in homes, businesses, and by industry.
25. What are some effects of hydropower?
Hydropower offers advantages over other energy sources but faces unique environmental challenges. It doesn’t pollute the air like power plants that burn fossil fuels, such as coal or natural gas. Impoundment hydropower creates reservoirs that offer a variety of recreational opportunities, notably fishing, swimming, and boating. Other benefits may include water supply and flood control. In contrast, hydropower dams can cause several environmental problems. Damming rivers may permanently alter river systems and wildlife habitats. Fish may no longer be able to swim upstream. Hydro plant operations may also affect water quality by churning up dissolved metals that may have been deposited by industry long ago. Hydropower operations may increase silting, change water temperatures, and lower the levels of dissolved oxygen. Some of these problems can be managed by constructing fish ladders, dredging the silt, and carefully regulating plant operations.
26. What are the materials used in Silicon PV Cell Production?
Silicon-based solar PV production involves many of the same materials as the microelectronics industry and, therefore, presents many of the same hazards. The production of silane and trichlorosilane results in waste silicon tetrachloride, an extremely toxic substance that reacts violently with water, causes skin burns, and is a respiratory, skin and eye irritant. Silicon tetrachloride can constitute an extreme environmental hazard. The extremely potent greenhouse gas sulfur hexafluoride is used to clean the reactors used in silicon production. The Intergovernmental Panel of Climate Change considers sulfur hexafluoride to be the most potent greenhouse gas per molecule; one ton of sulfur hexafluoride has a greenhouse effect equivalent to that of 25,000 tons of CO2. It can react with silicon to make silicon tetrafluoride and sulfur difluoride, or be reduced to tetrafluorosilane and sulfur dioxide. Sulfur dioxide releases can cause acid rain. Large quantities of sodium hydroxide are used to remove the sawing damage on the silicon wafer surfaces. In some cases, potassium hydroxide is used instead. These caustic chemicals are dangerous to the eyes, lungs and skin. Corrosive chemicals like hydrochloric acid, sulfuric acid, nitric acid and hydrogen fluoride are used to remove impurities from and clean semiconductor materials. Toxic phosphine or arsine gas is used in the doping of the semiconductor material. Read More>>
Source : Solar Industry Magazine