Energy Technology – Energy Consumption
There is only a limited supply of most technologically useful carriers of energy, such as coal and natural gas. Reducing energy consumption is thus a key challenge for engineers, architects, and transportation planners.
The difference between sensible and wasteful energy use is clearly evident in the case of lighting technology. Ordinary lightbulbs produce light when electricity flows through a metal filament; the filament’s resistance produces heat and it glows. Most of the energy it releases, however, is in the form of invisible ultraviolet radiation. The visible light emitted by a standard bulb represents only one to two percent of the electrical energy it consumes.
Fluorescent tubes and compact fluorescent lightbulbs, on the other hand, transform 10 percent of the electrical energy they use into visible light. In these bulbs, electricity stimulates the electrons in a gas, raising their energy levels and causing the gas atoms to emit ultraviolet radiation.
A layer of fluorescent material within the bulb then converts these ultraviolet emissions to visible light. Even more efficient are light-emitting diodes (LEDs). Like computer processors, LEDs are constructed from semiconducting materials. When an electrical current is applied to an LED, electrons within the semiconductor fall to a lower energy level and emit visible light. Due to this direct transformation of electricity into light, LEDs achieve efficiency levels of up to 20 percent.
“Passive houses”
Many people are careful to buy energy-efficient appliances and use compact fluorescent bulbs. However, the most significant factor in home energy consumption for most households is heating (and air-conditioning in warm climates). Fortunately, heating is also the area of household technology with the greatest potential for savings, above all through enhanced insulation.
State-of-the-art insulation, used and often required in new construction, significantly reduces heating and cooling costs in comparison with older homes. Especially in Europe, a standard known as the “passive house” calls for such efficient
“ENERGY HOGS”
Electric heating systems: When power plants generate electricity using a heat source (such as coal), large amounts of energy are wasted. Using the resulting electricity to produce heat for a home—again with substantial energy losses—can be extremely inefficient.
Sport utility vehicles: These popular vehicles combine the off-road and towing abilities of a pickup truck, while still being able to carry numerous passengers SUV’s attract extensive criticism for their low fuel efficiency, due to being classed as a “light truck” and so not having to conform to the stricter fuel standards for smaller passenger vehicles.
BASICS
HOW MUCH ENERGY DO THEY USE?
The following list shows the approximate power consumption of various devices and vehicles per hour:
• Lightbulb: 60 watts; equally bright compact fluorescent bulb: 11 watts; LED: 5-10 watts.
• Handheld hair dryer: 1,000-2,000 watts (1-2 kW)
• Electric stove: 2-10 kW • Gas heating for a single-family home (older construction): approximately 10-30 kW
• Compact car: 30 kW • High-performance sports car: 200-500 kW
• Intercity bullet train: approximately 3,000-8,000 kW
• Oil tanker: up to 100,000 kW