Renewable Energy How does energy use affect the environment? A) All forms of electricity generation have some level of environmental impact. However, clean energy technologies, including renewable energy and combined heat and power, have fewer impacts than other sources of electricity generation. How can I make a difference? B) In the United States, electricity is generated in many different ways, with a wide variation in environmental impact. Traditional methods of electricity production contribute to air quality problems and the risk of global climate change. With the advent of electric customer choice, many electricity customers can now choose the source of their electricity. In fact, you might now have the option of choosing cleaner, more environmentally friendly sources of energy. The energy decisions we make every day can encourage the development of new power sources, save natural resources, and help ensure that the quality of our environment is preserved. In many parts of the country, consumers now have the opportunity to choose the source of the power that is delivered to their home or business—including energy derived from renewable sources. C) "Renewable energy" generally refers to electricity supplied from renewable energy sources, such as wind and solar power (energy supplied by the sun), geothermal (energy created from the extreme heat contained in liquid rock—called magma (岩浆)—within the Earth's core), hydropower (energy derived from the movement of water as it flows downstream), and various forms of biomass (fuel from sources such as trees, wood and agricultural wastes and fuel crops). These energy sources are considered renewable because they are continuously replenished on the Earth. Hydrogen Energy D) Using hydrogen energy could help address many concerns facing our nation and our world. We believe hydrogen can contribute to resolving these issues for these reasons: Firstly, hydrogen can be made from a variety of domestic feedstocks like water, biomass, coal and natural gas. Second, hydrogen is non-toxic (无毒的), non-poisonous and will not contribute to groundwater pollution. It does not create "fumes" or other harmful emissions; in fact, using hydrogen in fuel cells produces only electricity and pure water. Furthermore, hydrogen is a key enabler for the development and more widespread implementation of renewable energy technologies, resulting in cleaner and more efficient products in the marketplace. E) Fifty million tons of hydrogen is produced each year worldwide, with nine million tons being consumed in the U.S. The challenge is to bring hydrogen into the everyday lives of customers as they begin to use hydrogen-powered vehicles and other applications. Geothermal Energy F) Our earth's interior—like the sun—provides heat energy from nature. This heat—geothermal energy— yields warmth and power that we can use without polluting the environment. Geothermal heat originates from Earth's fiery consolidation of dust and gas over 4 billion years ago. At earth's core—4,000 miles deep—temperatures may reach over 9,000 degrees Fahrenheit. Solar Energy G) Sunlight, or solar energy, can be used directly for heating and lighting homes and other buildings, for generating electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial uses. After the 1973 oil embargo (禁运), there was a resurgence (复苏) of interest in solar energy. Compared to the old forms of reducible energy (coal, oil, nuclear), solar energy offers a clean renewable form of energy. Wind Energy H) We have been harnessing the wind's energy for hundreds of years. From old Holland to farms in the United States, windmills have been used for pumping water or grinding grain. Today, the windmill's modern equivalent—a wind turbine (涡轮机)—can use the wind's energy to generate electricity. Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor (旋转器). I) A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity. Ocean Energy Basics J) The ocean can produce two types of energy: thermal energy from the sun's heat, and mechanical energy from the tides and waves. Oceans cover more than 70% of Earth's surface, making them the world's largest solar collectors. The sun's heat warms the surface water a lot more than the deep ocean water, and this temperature difference creates thermal energy. Just a small portion of the heat trapped in the ocean could power the world. K) Ocean thermal energy is used for many applications, including electricity generation. There are three types of electricity conversion systems: closed-cycle, open-cycle, and hybrid (混合的). Closed-cycle systems use the ocean's warm surface water to vaporize a working fluid, which has a low-boiling point, such as ammonia (氨). The vapor expands and turns a turbine. The turbine then activates a generator to produce electricity. Open-cycle systems actually boil the seawater by operating at low pressures. This produces steam that passes through a turbine/generator. And hybrid systems combine both closed-cycle and open-cycle systems. L) Ocean mechanical energy is quite different from ocean thermal energy. Even though the sun affects all ocean activities, tides are driven primarily by the gravitational pull of the moon, and waves are driven primarily by the winds. As a result, tides and waves are intermittent (断断续续的) sources of energy, while ocean thermal energy is fairly constant. Also, unlike thermal energy, the electricity conversion of both tidal and wave energy usually involves mechanical devices.

The next big breakthrough in artificial intelligence could come from giving machines not just more logical capacity, but emotional capacity as well. Feelings aren't usually associated with inanimate (无生命的) machines, but Posalind Picard, a professor of computer technology at MIT, believes emotion may be just the thing computers need to work effectively. Computers need artificial emotion both to understand their human users better and to achieve self-analysis and self-improvement, says Picard. "If we want computers to be genuinely intelligent, to adapt to us, and to interact naturally with us, then they will need the ability to recognize and express emotions, to have emotions, and to have what has come to be called emotional intelligence," Picard says. One way that emotions can help computers, she suggests, is by helping keep them from crashing. Today's computers produce error messages, but they do not have a "gut feeling" of knowing when something is wrong or doesn't make sense. A healthy fear of death could motivate a computer to stop trouble as soon as it starts. On the other hand, self-preservation would need to be subordinate to service to humans. It was fear of its own death that prompted RAL, the fictional computer in the film 2002: A Space Odyssey, to exterminate (消灭) most of its human associates. Similarly, computers that could "read" their users would accumulate a store of highly personal information about us—not just what we said and did, but what we likely thought, and felt. "Emotions not only contribute to a richer quality of interaction, but they directly impact a person's ability to interact in an intelligent way," Picard says. "Emotional skills, especially the ability to recognize and express emotions, are essential for natural communication with humans."

A recent study, published in last week's Journal of the American Medical Association, offers a picture of how risky it is to get a lift from a teenage driver. Indeed, a 16-year-old driver with three or more passengers is three times as likely to have a fatal accident as a teenager driving alone, by contrast, the risk of death for drivers between 30 and 59 decreases with each additional passenger. The author also found that the death rates for teenage drivers increased dramatically after 10 pm, and especially after midnight. With passengers in the car, the driver was even more likely to die in a late-night accident. Robert Foss, a scientist at the University of North Carolina Highway Safety Research Center, says the higher death rates for teenage drivers have less to do with "really stupid behavior" than with just a lack of driving experience. "The basic issue," he says, "is that adults who are responsible for issuing licenses fail to recognize how complex and skilled a task driving is." Both he and the author of the study believe that the way to mitigate (使......缓解) the problem is to have states institute so-called graduated licensing systems, in which getting a license is a multistage process. A graduated license requires that a teenager first prove himself capable of driving in the presence of an adult, followed by a period of driving with passenger restrictions, before graduating to full driving privileges. Graduated licensing systems have reduced teenage driver crashes, according to recent studies. About half of the states now have some sort of graduated licensing system in place, but only 10 of those states have restrictions on passengers. California is the strictest, with a novice (新手) driver prohibited from carrying any passenger under 20 (without the presence of an adult over 25) for the first six months.