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    Lesson
    ::经验教训

     

    Comparison of compact fluorescent bulb and chart showing electricity consumption by bulb type.
     

    Have you converted to compact fluorescent light bulbs at your house?
    ::您是否在家中改用紧凑型荧光灯灯泡?

    Compact fluorescent light bulbs are more efficient than incandescent light bulbs. Look at the chart and try to see how much more efficient. The answer is that they could be as much as six times more efficient. So why aren't all people using compact fluorescent bulbs all the time? Early ones were large and expensive, and many people don't like the color of the light. But they are much more environmentally friendly.
    ::紧凑型荧光灯灯泡比白炽灯泡更有效率。 看看这个图表, 并尝试看看它的效率有多高。 答案是, 它们的效率可以高达6倍。 那么为什么不是所有人都经常使用紧凑型荧光灯泡? 早期的灯泡规模大,价格昂贵, 许多人不喜欢光的颜色。 但是它们对环境更加友好。

    Net Energy
    ::净能源净能源

    Net energy  is the amount of useable  energy  available from a resource after subtracting the amount of energy needed to make the energy from that resource available. For example, every 5 barrels of  oil  that are made available for use require 1 barrel for extracting and refining the petroleum. What is the net energy from this process? About 4 barrels (5 barrels minus 1 barrel).
    ::净能源是指在从资源中减去能源使用所需的能源量之后,从资源中可获得的可用能源量;例如,每5桶可供使用的石油需要1桶石油来提取和提炼石油。这一过程的净能源是多少?大约4桶(5桶减1桶)左右。

    What happens if the energy needed to extract and refine oil increases? Why might that happen? The energy cost of an energy resource increases when the easy deposits of that resource have already been consumed. For example, if all the nearshore petroleum in a region has been extracted, more costly drilling must take place further offshore ( Figure   ). If the energy cost of obtaining energy increases, the resource will be used even faster.
    ::如果提炼和提炼石油所需的能源增加会怎么样?为什么会发生?当能源的简便储量已经耗尽时,能源资源的能源成本就会增加。 比如,如果一个地区的所有近岸石油都已经开采,那么更昂贵的钻井必须进一步离岸进行(图 ) 。 如果获取能源的能源成本增加,那么能源的使用将会更快。

    Offshore oil drilling platform at dusk, illustrating energy extraction challenges.
     
    Offshore drilling is taking place in deeper water than before. It takes a lot of energy to build a deep drilling platform and to run it.

    Net-Energy Ratio
    ::净能源比率

    The  net-energy ratio  demonstrates the difference between the amount of energy available in a resource and the amount of energy used to get it. If it takes 8 units of energy to make available 10 units of energy, then the net-energy ratio is 10/8 or 1.25. What does a net-energy ratio larger than 1 mean? What if the net-energy ratio is less than 1? A net-energy ratio larger than 1 means that there is a net gain in usable energy; a net-energy ratio smaller than one means there is an overall energy loss.
    ::净能源比率显示了资源可用能源量与获取能源所用能源量之间的差别。如果需要8单位能源才能提供10个单位能源,则净能源比率为10/8或1.25。净能源比率大于1的平均值是多少?净能源比率小于1?净能源比率大于1,净能源比率大于1意味着可用能源的净收益;净能源比率小于1,意味着总体能源损失。

    Table    shows the net-energy ratios for some common energy sources.
    ::表显示一些共同能源的净能源比率。

    Net-Energy Ratios for Common Energy Sources
    Energy Source Net-energy Ratio
      5.8
    Natural Gas 4.9
    Petroleum 4.5
    Coal-fired Electricity 2.5-5.1

    Notice from the table that solar energy yields much more net energy than other sources. This is because it takes very little energy to get usable solar energy. Sunshine is abundant and does not need to be found, extracted, or transported very far. The range for coal-fired electricity is because of the differing costs of transporting the  coal . What does this suggest about using coal to generate electricity? The efficiency is greater in areas where the coal is locally mined and does not have to be transported great distances ( Figure   ).
    ::从表格中注意到,太阳能比其他能源能产生的净能源要多得多。 这是因为获得可利用的太阳能需要很少的能源。 阳光充沛,不需要找到、提取或运输太远。 燃煤电的距离是因为煤炭运输成本不同。 这说明煤炭发电的成本不同。 煤炭是当地开采的,不需要迁移很远的地方,效率更高( 图 )。

    A freight train transporting coal through a barren landscape.
     
    Obtaining coal for energy takes a lot of energy. The coal must be located, extracted, refined, and transported.

    This is not to say that solar energy is less expensive than other types of energy. The cost of energy is dependent on lots of different factors, such as the cost of the equipment needed to harness the energy. If solar power cost less to use, it would be more widespread.
    ::这并不是说太阳能比其他类型的能源更便宜,能源成本取决于许多不同的因素,如利用能源所需的设备成本。 如果太阳能成本低于使用成本,它就会更加普及。

    Energy Efficiency
    ::能源效率

    Energy efficiency  describes how much useful work is extracted from one unit of energy. Remember that although energy is not created or destroyed, it's just transferred from one form to another, some energy is nearly always lost in the transfer as  heat . By saying that the work must be useful, it is possible to account for the energy that is lost to non-useful work. For example, some energy may not be doing useful work if the equipment is not running well (maybe a piston is moving sideways a bit rather than just up and down).
    ::能源效率描述从一个能源单位中提取多少有用的工作。 记住, 虽然能源不是创造或破坏的, 它只是从一种形式转移到另一种形式, 但有些能源几乎总是在作为热量的传输中丢失。 说这项工作必须有用, 就可以说明由于非有用工作而损失的能源。 例如, 如果设备运行不顺利, 有些能源可能不会起到有益的作用( 可能是活塞在向上向下移动, 而不是向下移动 ) 。

    Higher energy efficiency is desirable because:
    ::提高能源效率是可取的,因为:

    • Less energy is being wasted.
      ::能源浪费减少。
    • Non-renewable resources  will last longer.
      ::不可再生资源将持续更长的时间。
    • The cost is kept lower.
      ::费用降低。

    Because so much of the energy we use is from  fossil fuels , we need to be especially concerned about using them efficiently. Sometimes our choices affect energy efficiency. For example, transportation by cars and airplanes is less energy-efficient than transportation by trains.
    ::由于我们使用的大量能源来自化石燃料,我们需要特别关注高效使用化石燃料。 有时,我们的选择会影响能效。 比如,汽车和飞机的运输比火车的运输能效低。

    Summary
    ::摘要

    • Net energy is the amount of that is actually useable from an energy resource. Net-energy ratio is the ratio of the amount of useable energy from a resource and the amount it takes to make that energy useful.
      ::净能源是能源资源实际可以使用的能源量。 净能源比率是资源可用能源量的比率和使能源有用所需的能源量。
    • Many factors besides net-energy ratio go into determining if a type of energy will be used.
      ::除了净能源比率之外,许多因素也影响到确定是否将使用某种能源。
    • An energy source with high energy efficiency provides a lot of work for the amount of energy used.
      ::高能效的能源为所使用能源的数量提供了大量的工作。

    Review
     ::回顾

    1. Compare and contrast net energy, the net-energy ratio, and energy efficiency.
      ::与净能源、净能源比率和能效进行比较和对比。
    1. Since the net-energy ratio for solar energy is higher than other types of energy, why don't we use solar for electricity almost exclusively?
      ::既然太阳能的净能源比高于其他能源, 为什么我们不完全用太阳能发电?
    1. Why would the energy needed to make a type of energy useful increase or decrease? In other words, why would the net-energy ratio change?
      ::为什么能源需要使一种能源有用地增加或减少? 换句话说,净能源比率为什么会改变?

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.
    ::使用此资源回答下面的问题 。

     

     

     

     

    1. Besides energy, what is lost when energy drips away?
      ::除了能源之外,当能源流失时又会失去什么?
    1. Why should you replace incandescent bulbs with CFLS?
      ::为什么要用CFLS取代白炽灯泡?
    1. Why is it good to plug electronics into a power strip?
      ::为什么把电子设备插上电源条很好?
    1. Why should you use a programmable thermostat?
      ::为什么你要使用可编程的自动调温器?
    1. What is the purpose of insulation?
      ::绝缘的目的是什么?
    1. Why is an old appliance an energy sink?
      ::为什么老旧的电器是能量池?
    1. If you did these things, how much money would you save in a decade on average (in Minnesota)?
      ::如果你做了这些事 你会在十年内平均节省多少钱 (明尼苏达州)?