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英語四級(jí)

發(fā)布時(shí)間: 2017年01月03日

英語四級(jí)聽力只為你量身定制 每天一練(9.28)

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Rural communities in developing countries often have trouble securing dependable supplies of energy for cooking and lighting. But energy exists every where organic waste is breaking down. It is just a question of how to harness or make use of it.

A Palestinian community in the West Bank has been successfully testing a device that turns food and animal wastes into biogas. The village of al-Awja has no running water or electric power. Solar panels provide energy from the sun, but not enough for cooking equipment. But as in many other parts of the world, villagers keep chickens, cows or other animals.

Recently, about 40 families started using portable devices that turn food and animal waste into methane gas. The European Union and the Peres Center for Peace provided money to pay for the devices.

One villager says, "This is a very good machine... The machine provides us with 70 to 80 percent of the gas that we need for our household."

An Israeli company, HomeBioGas, designed the machine, called a bio-digester. Anaerobic bacteria are added to the device the first time it is used. The bacteria helps break down organic waste. The bio-digester creates enough methane for cooking three meals a day. It also produces about 10 liters of liquid organic fertilizer.

Biogas is smokeless and has no smell. In addition to cooking, biogas can be used to heat water and for lighting devices. A built-in, hand-powered grinder helps break down the solid parts in household waste.

The HomeBioGas system is designed for areas where the daily temperature does not drop below 15 degrees Celsius. The price is about $2,500, a somewhat pricey amount for most families. So, communities must depend on aid from governments or private donors.

But the designers note the system can also be useful in more wealthy communities that have organic waste which can be turned into clean energy.

I'm Jonathan Evans.

VOA's George Putic reported this story from Washington. Jonathan Evans adapted it for Learning English. George Grow was the editor.

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