Biogas is gas made when plant material — and often animal waste too — rots in a closed place with little air. People catch that gas and burn it for cooking, heat, or electricity.

plant material植物材料 — and often animal waste too，有時候也包括動物排泄物 — rots in a closed place with little air在密閉、空氣稀少的地方腐爛時 is gas made所產生的氣體，Biogas就是沼氣。People catch that gas人們會收集這種氣體 and burn it for cooking, heat, or electricity拿來燒飯、取暖，或發電。

On a farm it can come from dung and leftover plants; in a city, from food waste.

On a farm在農場 it它 can come from dung and leftover plants可能來自糞便和剩下的植物；in a city在城市 from food waste則可能來自廚餘。

The useful part is mostly the same kind of gas as in a kitchen stove, but it did not come from a hole in the ground. Though actually, raw biogas is not as clean as the gas in city pipes; it usually needs cleaning before it is nice to burn.

The useful part有用的那部分 is mostly the same kind of gas as in a kitchen stove大致上跟廚房瓦斯爐用的是同一種氣體，but只是 it did not come from a hole in the ground它不是從地底的洞裡來的。Though actually不過其實，raw biogas未經處理的biogas is not as clean as the gas in city pipes沒有城市管線裡的瓦斯那麼乾淨；it usually needs cleaning通常要先清理過 before it is nice to burn燒起來才好用。

It is a real biofuel, the gas kind, and a way of getting bioenergy.

It它 is是 a real biofuel真正的生質燃料，the gas kind氣體的那一種，and a way of getting bioenergy也是取得生質能的一種方式。

The word is a bit technical in English, but the idea is old and practical: rotting stuff gives off gas you can use. Do not picture the air we breathe; this is fuel gas.

The word這個字 is a bit technical in English在英文裡有點技術性，but但 the idea is old and practical概念其實古老又實際：rotting stuff gives off gas you can use腐爛的東西會放出可以使用的氣體。Do not picture the air we breathe不要把它想成我們呼吸的空氣；this is fuel gas這是燃料用的氣體。