At the 1900 World's Fair in Paris, Rudolf Diesel exhibited an engine that could run on oil from vegetables and plants. But Diesel's design was eclipsed by automobile engines that ran on petroleum-based fuel. Today, though, with concerns about the environment and the supply of oil, diesel engines – and the sustainable options for running them – are getting a second look. Auto industry analysts expect sales of diesel-powered cars in the United States to triple in the next decade, and many of those drivers will be looking for plant-based fuel, "bio-diesel," to put in their tanks. Jan Sluizer has more on what some say is the fuel of the future.
Biodiesel is made from processed vegetable or plant oil, and can be used in diesel engines on its own, or blended with petroleum-based fuel. Here in Berkeley, California, the pumps at Biofuel Oasis dispense diesel made from used cooking oil.
The fueling station is a cooperative, owned by five women. Margaret Farrow says Oasis was opened to offer a sustainable option to the petroleum-derived diesel offered by big oil companies. "It's a clean-burning fuel. It's more efficient than gasoline. It's biodegradable, non-toxic, non-flammable," she says, adding that it's good for the environment, too. "In terms of greenhouse gasses, if you use biodiesel, there's no net increase of carbon dioxide going into the environment."
Since Biofuel Oasis opened in 2003, about 2,500 customers have pulled in to fill up. For Sandra Lupien, coming here is an ethical choice. "An important point for me about using biodiesel is to make sure that we're using biodiesel that is made from recycled vegetable oil, oil picked up from restaurants that's just going to be thrown away anyway, instead of using oil processed from new crops."
There are two types of biodiesel fuel: Fresh or "virgin" biodiesel is made from crops such as soybeans. Then there's the biodiesel fuel made from recycled vegetable oil which only a few fueling stations besides the Oasis sell – currently at $1.10 ten per liter, about five cents less than regular diesel fuel and ten cents more than gasoline in California.
Even though diesel is more expensive than gasoline, liter for liter, it's cheaper to run a diesel car. Diesel engines are designed to be more efficient than gasoline engines, so they provide higher fuel efficiency. But it can be more of a challenge to find a place to fill up a car that runs on diesel. Not all service stations carry diesel, and pumps serving up biodiesel are rare indeed. Nationally, there are only about 1600 biodiesel fueling stations, with most clustered in the grain-growing states of the Midwest, and a few along the coasts.
The biodiesel sold at Oasis comes from Yokayo Biofuels, the only commercial-scale plant in northern California that manufactures the fuel from used vegetable oil. Kumar Plocher founded the company in 2001, and it now produces about 3700 liters of biodiesel fuel every day.
Plocher has a fleet of biodiesel-powered trucks that collects used cooking oil from about 700 restaurants across northern California. Once at the processing plant, the oil goes through a series of screeners, high-speed shakers, hot tanks and washes to remove food residue and water. The separated food products are composted, and the filtered oil begins its transformation. Treated with methanol and potassium hydroxide, also known as lye, the vegetable oil molecules break down.
Plocher explains that this step is the most dangerous aspect of the operation. "People ask if biodiesel is a dangerous fuel. Once you've actually made it and purified it, it's completely non-toxic and non-hazardous."
But Plocher admits there is still a great deal of negativity surrounding biodiesel fuels. "Right now the [public sentiment] about biofuels in general and, certainly, biodiesel as well as ethanol, is very negative." He points to news reports and studies focused on the diversion of food crops for fuel and the environmental costs of clearing land for biofuel crops. And he counters, "It's very easy to show that this kind of biodiesel that we're making has serious net positives. But if you're going to take an acre of someone's food garden and replant it to make energy, there's problems with that."
Plocher says because of the huge amount of land required to grow biodiesel crops – often land where food crops had been grown – some biodiesel producers are importing palm oil from the tropics to make their fuel. But that's not a perfect solution, either. Not only are there increased transportation costs, but the growing demand for palm oil has caused the destruction of rainforests in Malaysia, Indonesia and other tropical countries.
Kumar Plocher serves on the National Biodiesel Board's Sustainability Task Force, working to develop a road map for the industry. With an eye on its impact on the environment and the global food supply, he says, the search is on for sustainable, super biodiesel crops, "stuff that doesn't compete with food, that you can get a whole lot of energy per hectare."
He says soybeans provide only a tiny amount of oil, and mustard seed and sunflowers are somewhat more productive. "But there are trees that actually grow well in California and across a lot of the United States called Chinese Tallow trees. They can give you upwards of 4,730 liters a hectare. We're looking into those. Difficult to harvest but they can be one of the real feedstocks of the future." Algae is another possibility, he says. "We can get [tens of thousands of liters per hectare] with algae ponds. So there are all kinds of more sustainable choices for the future."
Whatever it's made from, industry experts expect biodiesel to be an important part of the energy supply of the future.
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1900年在巴黎举行的世界博览会上，德国工程师鲁道夫.狄塞尔展出了一台使用蔬菜和植物油的发动机。但是狄塞尔的设计被以石油提炼的汽油为燃料的汽车引擎所取代。
而今天，出于对环境和石油供应的考虑，柴油发动机，以及所使用的可持续性能源，再次受到人们的注意。汽车工业的分析人士预期，美国在未来十年，柴油动力车辆的销售将上升三倍,而且很多驾车人都将寻求植物燃油，也就是生物柴油。
生物柴油是由蔬菜或植物油提炼出来的，它可以单独使用于柴油引擎，或者和石油类的燃料混合使用。
在加利福尼亚州伯克利的奥西斯生物柴油加油站的柴油是从使用过的菜油提炼出来的。这个加油站是由五名女性合办的企业，玛格丽特.法罗说，她们开办这个加油站，是要在大型石油公司所供应的石油提炼的柴油之外，提供另一种可持续性的燃油选择。
“我们提供的是清洁燃料，比汽油的效率要高。它是可生物降解的，无毒性的，不易燃。在温室气体问题上，使用生物柴油不会增加环境中的二氧化碳。”
自从奥西斯生物柴油站2003年开设以来，一共有两千五百来名顾客前来加油。桑德拉.鲁宾就是其中之一。
“我用生物柴油的一个重要理由，是因为它是从回收的植物油，从餐馆收集的原来准备扔掉的废油中提炼出来，而不是由新鲜的农作物提炼出来的。”
生物柴油分为两种：一种是新鲜或原生油，是从农作物，例如黄豆中提炼的。另一种是从回收的植物油提炼的。除了这家油站之外，只有几家油站出售这种产品。目前的价格是每公升一点一美元，比普通柴油便宜五美分，比加州的普通汽油贵十美分。
即使柴油每公升价格比汽油贵，但就耗油量来说，柴油车还是比较便宜。柴油引擎的设计比汽油引擎的效能更高，所以柴油更节能，但是，找到柴油加油站可能要多费些功夫，因为不是每个加油站都有柴油，而供应生物柴油的加油站更是凤毛麟角。在全美国，只有大约一千六百家生物柴油站，大部分在中西部和海岸地区。
奥西斯油站出售的生物柴油来自位于加州北部的美国唯一的一家以回收植物油为原料的炼油厂。
库玛尔?普洛克尔是位于加州的这家生物燃料厂的创办人和总裁。这个工厂在旧金山北边，大约两个小时的车程。犹凯欧炼油厂从2001年起开始营运，现在每天大约生产三千七百公升的生物柴油。
普洛克尔拥有一个使用生物柴油的卡车队，每天从北加州大约七百家餐馆收集使用过的烹饪用油。这些回收油送到工厂后，要经过一系列的过滤程序，还要经过高速震动、热箱和洗涤，以除去食物残渣和水分。食物分离出之后，过滤好的油用甲醇和氢氧化钾处理后，植物油中的分子开始分裂。
“这是我们作业程序中最危险的部分。有人问生物柴油有没有危险性，答案是，一但将它纯净化了，它就完全无毒而且没有危险。”
但是，普洛克尔承认，人们对生物柴油仍有一些负面看法。
“很多人问，生物柴油对地球是否负面影响较大，我们生产的生物柴油只有明显的正面影响。但是如果你把种植食物的一英亩地，改种能源作物，那就有问题了。”
普洛克尔同时也是国家生物柴油委员会可持续性能源工作小组的成员。这个小组的任务是制定开发生物柴油的路线图。对于这项计划对环境和全球食物供应的影响，他说，他们的研究着重在可持续性的和超级生物柴油农产品。
不论生物柴油的原料是什么，专家们预期，它将成为未来能源供应的重要一环。
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