Forget chip fat, sugar cane or rapeseed oil – the latest source of biofuel could be watermelons.

    Scientists have discovered that the fruit is a great source of sugar that can be readily distilled into alcohol to power cars and farm machinery.

    And because retailers rejects 360,000 tons of "substandard" fruit annually in America alone they could be used as an economical way to make fuel.

    The waste from US growers could produce nearly two million gallons （nine million litres） of biofuel per year.

    In the study, researchers at the United States Department of Agriculture set out to determine the biofuel potential of juice from 'cull' watermelons – those not sold due to cosmetic imperfections, and currently ploughed back into the field.

    About a fifth of each annual watermelon crop is left in the field because of surface blemishes or because they are misshapen.

    Dr Wayne Fish, who led the team, found that 50 per cent of the fruit was fermentable into ethanol which could provide valuable fuel.

    "We've shown that the juice of these melons is a source of readily fermentable sugars, representing a heretofore untapped feedstock for ethanol biofuel production," he said.

    The study, published in the journal Biotechnology for Biofuels, discovered that watermelons could produce around 20 gallons of fuel per acre from fruit that otherwise would go to waste.

    Production of biofuels has been targeted by western governments as a way to bolster renewable energy targets.

    The European Union has a target for 2010 that 5.75 per cent of transport fuels should come from biological sources, but the target is unlikely to be met.

    The British government's Renewable Transport Fuel Obligation requires five per cent of the fuel sold at the pump by 2010 to be biofuel.

    不用再考慮剩油、甘蔗和菜籽油了--西瓜可成為生物燃料的一個最新來源。

    科學家發現，西瓜中含有大量糖份，糖可直接用于提煉酒精，從而為汽車和農用機械提供動力。

    每年僅美國的零售商遺棄的"不合格"水果就達36萬噸，而這些水果可通過一種十分經濟的方法來制造酒精。

    美國水果種植商每年扔掉的水果可生產出近200萬加侖（900萬公升）的生物燃料。

    在這項研究中，美國農業部的研究人員開始測定這些"被淘汰"西瓜的汁液究竟具有多大的潛在利用價值。被淘汰西瓜指的是那些由于外表瑕疵未上市，又被淘汰回地里的西瓜。

    每年約有五分之一的西瓜因外表瑕疵或形狀不規則而被丟棄。

    研究小組負責人韋恩？費什發現，50%的西瓜可發酵產生乙醇這種寶貴的燃料。

    他說："我們發現西瓜汁中含有易發酵糖，這種原料在乙醇生物燃料的生產中尚未被利用過。"

    這項在《生物燃料的生物科技》期刊上發表的研究發現，每英畝的西瓜能產生約20加侖的燃料，而（如果不加以利用，）這些水果就會被白白浪費。

    西方國家瞄準制造生物燃料，以此促進可再生能源的發展。

    歐盟計劃到2010年實現"5.75%的交通燃料源于生物燃料"的目標，但似乎很難實現。

    英國政府的《可再生交通燃料義務法》規定，到2010年，生物燃料占加油站所售燃料的比例應達到5%.