Renewable Energy

Overview

This unit is designed to engage sixth grade students using hands-on investigative activities that will increase their awareness of solar energy. The primary objectives comply with the New Mexico standards for Science for sixth grade and will be identified at the beginning of each activity described in this unit. The unit will be a study about solar energy and it will entail mini lessons on the sun's composition, positioning in our solar system, role it plays as the Earth's closest star, and an investigation and discussion about energy and its transformation into various forms. The culminating activity will be the construction of a model solar car. The objective is to have students begin thinking about renewable energy and the need for alternative fuels in their future. Although the unit is designed to be taught in its entirety and, therefore, will take several weeks to teach, it is plausible for a teacher to extract a particular lesson plan if time does not allow for the teaching of the complete unit. Students will use scientific thinking and practice to understand the processes of scientific investigations and use inquiry and scientific ways of observing, experimenting, predicting, and validating to think critically. This unit will be taught in the fall so that students will take full advantage of the sun's inclination for the construction of their model solar car, as well as be able to observe deciduous trees using light energy to conduct photosynthesis.

Introduction

I first became interested in environmental issues twenty years ago when I attended a conference in Denver, Colorado on the greenhouse effect. As many people know, the greenhouse effect is a naturally occurring phenomenon attributed to the composition of our Earth's atmosphere. When light energy from the sun reaches the Earth some of it is reflected back to space and the rest is absorbed. Al Gore's book, An Inconvenient Truth, has an illustration of this process [1]. The light energy is absorbed and the Earth is warmed. The energy not absorbed by the Earth is then re-radiated back toward space as long-wave radiation or infrared waves. This outgoing long-wave radiation is partially trapped by greenhouse gases. These gases trap some of the heat inside the atmosphere of the Earth and enable the Earth to be a habitable environment for people and other living organisms. This greenhouse effect keeps the surface temperature of the Earth at approximately 10 degrees centigrade and without the greenhouse effect, the average surface temperature of the Earth would be approximately -25 degrees centigrade. Human habitation on Earth would be impossible at these temperatures. Carbon dioxide is one of the most abundant greenhouse gases and currently the number one topic when discussing climate change. Other greenhouse gases include methane and water vapor, which trap and radiate the Sun's light energy in all directions, warming the Earth's surface and atmosphere [2].

The Greenhouse Effect and Global Warming

Why is it important to understand the greenhouse effect and its impact on global warming? Today, it is hard to watch the news or read the paper without hearing or seeing something being discussed about carbon dioxide emissions (CO ₂). Up until recently, the last two hundred years or so, the Earth's atmosphere has been relatively stable and existing in a place of equilibrium that provided the perfect balance of gases for human habitation. Current research is showing that CO ₂ levels are increasing at an alarming rate compared to historical trends of the past [1]. Unfortunately, this isn't new news. The prediction that burning of fossil fuels would increase the amount of carbon dioxide in the atmosphere and lead to global warming was made as early as 1896 by the Swedish chemist Svante Arrhenius — he also coined the phrase "greenhouse effect" [3]. The industrial revolution had a tremendous impact on pollution and started the increase in greenhouse gas production by humans, who are responsible for the current levels of CO ₂ in the atmosphere, which is warming our Earth and causing dangerous scenarios for us in the near future. The hottest year on record from 1860 to 2005 was the year 2005 worldwide [1]. It is this warming trend that has made global warming a household phrase. How did this happen?

Although many greenhouse gases are naturally occurring, we humans have accelerated the rate of their production and release back into the atmosphere. The Intergovernmental Panel on Climate Change — a panel of more than 2,500 scientific experts from 130 countries — concluded in their report in the spring of 2007 that CO ₂ emissions have grown between 1970 and 2004 by about 80% and represented 77% of total global greenhouse gas emissions in 2004 [14]. Carbon dioxide has increased since pre-industrial times from 280 parts per million to 381 parts per million [1]. In the United States, transportation accounted for nearly 2 billion metric tons of our national CO ₂ emissions; a full 33% of the carbon dioxide we put in the atmosphere as a nation comes from tailpipes, this stated by Environmental Action [15]. Fossil fuels are fuels formed in the ground from the remains of dead plants and animals. It takes millions of years to form fossil fuels. Oil, natural gas, and coal are fossil fuels. The rest of the carbon dioxide comes from destroying vegetation, mainly the felling of forests; trees soak up CO ₂ when alive and store it, but release it when they are cut down and/or burned [3]. The other greenhouse gases, methane and nitrous oxide, are given off by burning fossil fuels, as well as by vegetation. Nitrous oxide is also emitted by fertilizers and methane is released into the atmosphere by rice paddies and cattle. It is the rate and the amount of these gases being release into our atmosphere that concerns scientists today. What will happen to the Earth and its inhabitants as the temperature rises?

The Effects of Global Warming

It is predicted that the level of CO ₂ will double from the concentration of CO ₂ in the atmosphere before the Industrial Revolution; approximately 14 billion tons of carbon a year in 2056 will be emitted. Global Warming will lead to a redistribution of heat from the Equator to the poles, which drive wind and ocean currents like the Gulf Stream [1]. These currents have followed the same patterns for years and a disturbance would have incalculable consequences for all of mankind. The average worldwide temperature is around 58°F and even an increase as small as 5°F will have a major impact especially on the poles, which in turn will change weather patterns [14]. The unpredictable nature of climate change during this time of global warming will have devastating effects on agriculture worldwide. In the past when the world was not as heavily populated, people had the opportunity to migrate to more hospitable climates and regions around the globe, but with the current population at over 6 billion people it is difficult to fathom where anyone would go to seek refuge on an already overcrowded planet.

Another consequence will be the rise of sea levels around the globe. Within the course of the next 100 years, we will see the sea levels increase by a meter or more. This will impact many urban areas living along the coast such as Manhattan, Los Angeles, and many others major metropolitan areas in which millions of people will be affected. Many islands will be under water and the Nile Delta, which is densely populated, is sinking and it is reported that by the year 2050, up to 19% of Egypt's cultivable land, home to 16% of the population, could disappear [9]. Many of us are all too aware of the temperature changes that have increased the intensity of hurricanes, as demonstrated by the damage caused by Hurricanes Katrina and Rita. Heat waves have hit both the United States and Europe causing a larger number of fatalities than in previous years.

Is there a Solution?

It would appear that an easy solution to stop global warming would be to reduce the amount of fossil fuels being burned, which in turn would decrease the amount of CO ₂ released into the atmosphere. Many advocacy groups such as The Carbon Neutral Group are helping both industry and individuals calculate carbon emissions [7]. Once you are aware of the amount of carbon that your everyday activities such as cooking, driving, and heating or cooling your home give off, then you can reduce your impact to the equivalent of zero by purchasing carbon offsets. The offsets fund projects that reduce greenhouse-gas emissions elsewhere by increasing energy efficiency, developing renewable energy, or restoring forests with the planting of new trees. Buying carbon offsets is one method that people are engaged in currently, but this process will not end global warming; it will, however, slow down the rate at which carbon is being emitting into the atmosphere. However, the issue of reducing greenhouse gas emissions is complicated by the fact that most of the world's energy comes from the burning of fossil fuels. The inexpensive cost of burning fossil fuels combined with their abundance and extractability has made them the number one choice of fuel for most developed countries across the globe. Coal continues to be available and China, the fastest growing country, has an abundant source and is burning this fossil fuel with little or no regulatory oversight. Therefore, they are burning a fossil fuel that is spewing out carbon at a very high rate and they are not offsetting it.

The impetus to move away from fossil fuels will be cost and necessity. For those countries dependent on oil or petroleum-based products, there will no longer be oil from which to extract in fifty years. Countries dependent on oil, such as the United States, will need to find new sources of energy. The 2004 British Petroleum Statistical Review of World Energy predicted that global oil reserves will be gone in 2045 with the United States running out of its oil reserves by 2015, based on known reserves and current rates of consumption ratio [4].

So, here we are in a nation that is oil dependent and yet our supply is about to run out. What's next? What is the next fuel to take us into the future? Alternatives to fossil fuels must be made a priority. Renewable energy can be generated in many different ways and several examples come in the form of wind, biomass, and solar. These energy forms are renewable and generally speaking have significantly less carbon emissions than burning fossil fuels; therefore, they are referred to as "clean energy". Technology for acquiring alternative fuels from renewable energy already exists, but the methods for storage and distribution are extremely costly. It appears that there will no longer be a single source for our energy needs. In order to reduce our CO ₂ emissions, we will have to rely on a variety of energy sources. We will have to make sacrifices both financially and in the way we live our daily lives. Conservation will no longer be a "good idea"; it will be the way of life, if we are to sustain our civilizations under the heat of global warming.