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.

    不用再考虑剩油、甘蔗和菜籽油了--西瓜可成为生物燃料的一个最新来源。

    科学家发现，西瓜中含有大量糖份，糖可直接用于提炼酒精，从而为汽车和农用机械提供动力。

    每年仅美国的零售商遗弃的"不合格"水果就达36万吨，而这些水果可通过一种十分经济的方法来制造酒精。

    美国水果种植商每年扔掉的水果可生产出近200万加仑（900万公升）的生物燃料。

    在这项研究中，美国农业部的研究人员开始测定这些"被淘汰"西瓜的汁液究竟具有多大的潜在利用价值。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。

    每年约有五分之一的西瓜因外表瑕疵或形状不规则而被丢弃。

    研究小组负责人韦恩？费什发现，50%的西瓜可发酵产生乙醇这种宝贵的燃料。

    他说："我们发现西瓜汁中含有易发酵糖，这种原料在乙醇生物燃料的生产中尚未被利用过。"

    这项在《生物燃料的生物科技》期刊上发表的研究发现，每英亩的西瓜能产生约20加仑的燃料，而（如果不加以利用，）这些水果就会被白白浪费。

    西方国家瞄准制造生物燃料，以此促进可再生能源的发展。

    欧盟计划到2010年实现"5.75%的交通燃料源于生物燃料"的目标，但似乎很难实现。

    英国政府的《可再生交通燃料义务法》规定，到2010年，生物燃料占加油站所售燃料的比例应达到5%.