Researchers from the University of Nevada, Reno, have discovered that coffee can be turned into an alternative fuel other than caffeine: biodiesel. And you can have your coffee and drink it too. No need to use the fresh stuff, old grounds are more than up to the task, according to material scientist Mano Misra and his colleagues.

Even after being subjected to the rigors of brewing, roughly 15 percent of the weight of dried coffee grounds is oil, which, much like palm and soybean oil, can be converted into biodiesel. The coffee has the added benefit of not being a food source, like palm oil and soybeans.

Nevertheless, more than 16 billion pounds of coffee are produced globally every year, according to the U.S. Department of Agriculture. Misra estimates that the grounds from that haul could be used to make as much as 340 million gallons of biodiesel. For their part, the researchers turned grounds donated by Starbucks into biodiesel that had the added advantage of smelling like a fresh cup o' Joe.

The researchers note that coffee's high proportion of antioxidants, such as chlorogenic acid, acts as a natural preservative for the resulting biodiesel, preventing it from going bad like other forms of biofuel and even petroleum diesel can. The researchers hope to set up a pilot plant to convert grounds into biodiesel next year and estimate that, for its part, Starbucks in the U.S. alone could turn a profit of $8 million a year from the process, assuming that both the biodiesel and leftovers of the process can be sold.

To chill this simmering cup a bit: the U.S. Department of Energy says that the U.S alone burns 40 billion gallons of diesel a year, meaning that converting all the grounds in the world wouldn't even contribute 1 percent of U.S. diesel consumption. Still, it's an idea that could perk you up.

來自位于里諾的內華達大學的研究者們發現，咖啡可以被轉變為替代燃料：生物柴油，而不是咖啡因。當然你仍然可以得到咖啡喝。根據材料科學家Mano Misra和他的同事們的研究，作燃料用的咖啡不需要使用新鮮的咖啡，剩余的咖啡殘渣就足夠用了。

咖啡即使泡過，剩余咖啡殘渣中占重量大約15% 的部分仍然是油，這些油就像棕櫚油和黃豆油一樣，可以被轉化成生物柴油。棕櫚油和大豆油是人們的食物來源，而用咖啡作燃料的另外一個好處就是它不是食品來源。
 
根據美國農業部的數據，全球每年產出超過160億磅的咖啡。Misra估算，用這些大量咖啡的剩余殘渣可以制造出多達3.4億加侖的生物柴油。研究者們把星巴克贈給他們的咖啡殘渣轉變成生物柴油，這些柴油聞起來還有一種新鮮咖啡的味道呢！

研究者們注意到咖啡中高含量的抗氧化劑，比如綠原酸，對所生產的生物柴油能起到天然防腐劑的作用，這樣就可以防止這種生物柴油變味，而其它形式的生物柴油甚至石油柴油都能變味。研究者們希望明年建立一個把咖啡殘渣轉化成生物柴油的實驗工廠。他們估計，假設由此生產的生物柴油以及該加工過程中獲得的其它東西能被賣出的話，那么僅僅在美國的星巴克一年就可以從中獲得800萬美元的利潤。

前景似乎不錯，不過還是要潑點冷水。美國能源部稱，僅美國一個國家一年就要燒掉400億加侖的柴油，這意味著即使把全球的咖啡殘渣都轉化成生物柴油，這還不能滿足美國柴油消耗的1%。但是，把咖啡殘渣變廢為寶的想法可能還是能使你為之一振吧！

Vocabulary:

Alternative: 選擇
Caffeine: 咖啡因
Biodiesel: 生物柴油
Rigor: 嚴格；精確
Brew: 釀造
Palm: 棕櫚
Convert: 轉化
A fresh cup o' Joe：（口語）一杯新鮮咖啡
Antioxidant: 抗氧化劑
Chlorogenic acid: 綠原酸
Preservative: 防腐劑
Chill: 冷卻
Simmer: 小火慢煮；心中充滿
Perk up: 活躍起來；振作精神