While new drilling technologies and oil reserves are taking the pressure off gasoline prices and peak production issues, demand for alternative fuel vehicles continues to grow. Environmental concerns and government regulations have made finding substitutes for the conventional gasoline-powered internal combustion engine a priority for both manufacturers and consumers. The federal government is demanding an average of 54.5 miles per gallon by 2025 -- a challenging target for traditional technologies. California is requiring increasing numbers of zero-emission or plug-in hybrid cars.

    But what direction to go? Depending on considerations like usage patterns, efficiency, and cost, there are at least a dozen substitutes for gasoline as motor fuel, including electricity, natural gas, vegetable oil, and even sunlight.

    Even the most promising ones like natural gas, as John O'Dell of Edmunds.com points out, are handicapped by the same thing: a lack of infrastructure for refueling or recharging.

    With that in mind, here's a look at the alternatives that are available today, along with some tentative predictions about their prospects for the future.

    尽管现在新的钻探技术和新探明石油贮量使油价和最高产量问题面临的压力有所减轻，但对替代燃料汽车的需求仍然在增长。环境问题和政府管制已经使寻找传统汽油内燃机的替代品成为汽车厂商和消费者的当务之急。联邦政府要求，到2025年平均每加仑英里数应达到54.5英里——这对传统技术来说是一个极其具有挑战性的目标。加州则已经开始要求增加零排放汽车或插电式混合动力车的数量。

    但是应该朝哪个方向努力呢？考虑到诸多因素，如使用习惯、效率和成本等，能替代汽油的东西有十几种，比如电力、天然气、植物油，甚至还有太阳能。而正如汽车网站Edmunds.com的约翰•欧戴尔所指出的那样，就算天然气这样最有希望的替代品，它的推广也受到同一件事的阻碍：加油或充电基础设施的匮乏。

    考虑到这一点，我们来看看一些现有替代品的情况，以及关于它们未来应用的尝试性预测。

    1. Gas-electric hybrids

    The first hybrid models, the Honda Insight and Toyota Prius (above) both reached the U.S. in 1999, and today some 40 gas-electric models are for sale. Using electricity to partially power vehicles has significant fuel economy and emissions benefits. Gas-electric hybrids use a battery to provide power at low speeds, or to handle stop/start. The battery is charged through regenerative braking and by the internal combustion engine, and it need not be plugged in. While Toyota's (TM) popular Prius remains the best-selling hybrid -- more than 200,000 will be sold in 2013 -- their numbers now include supercars made by Ferrari and Porsche. The Porsche Panamera S hybrid has a 3.0 liter V6 engine and still gets 22 mpg city/30 mpg highway.

    1. 油电混动

    本田Insight和丰田普锐斯（Prius）是第一代混动车，它们都是1999年在美国上市的，而今天在售的混动车已经有40种。部分使用电能驱动汽车在燃油经济性和排放上都有很大好处。油电混合动力车用电池在低速行驶时供能，或控制启停。这种电池通过再生制动或内燃机充电，无须插电。虽然丰田广受欢迎的普锐斯一直是最畅销的混动车（它2013年的总销量将超过20万辆），但现在法拉利（Ferrari）和保时捷（Porsche）也开始推出超级混动车了，比如保时捷帕纳梅拉S混动车搭载了一台3.0升的V6引擎，但续航能力仍能达到城市路况每加仑22英里，高速公路每加仑30英里。

    2. Plug-in hybrids

    Plug-in hybrids or PHEVS are similar to gas-electric hybrids but have larger batteries that can propel the car limited distances on electricity alone, thus generating zero emissions. The batteries can then be recharged by being plugged into an electric power source. The cost of the larger batteries carries a hefty price premium -- an additional $7,000 for the plug-in version of the Prius before a recent price cut -- and only four PHEV models are currently available in the U.S. Sales of the best-known model, General Motors' (GM,Fortune 500) range-assisted Chevrolet Volt (above), have been running at less than 2,000 a month.

    2. 插电式混动

    插电式混动车也叫PHEV，它与油电混动车类似，但电池容量更大，能光靠电能推动车行驶一定距离，也因此实现了零排放。这种电池随后能插在电源上充电。容量更大的电池成本也随之水涨船高——比如插电式普锐斯在最近降价前就需要多花7,000美元——而且目前美国在售的PHEV只有四种。通用汽车（General Motors）那款大名鼎鼎的增程式雪佛兰沃蓝达（Volt）每月销量也不足2,000辆。

    3. Electrics

    Electric vehicles (EVs) run gasoline-free; they use a battery to store the electric energy that powers the motor. Acceptance of pure EVs has been slowly growing since they were introduced to the mass market three years ago, with increased demand both at the low end of the market, following price cuts on the $30,000 Nissan Leaf (above), and at the top with the surprising success of the $80,000 Tesla Model S. Range anxiety continues to be a deterrent to greater buyer interest, as does the limited number of charging stations outside major cities. Eleven different EV models from mainstream manufacturers were on sale in 2013, among them Mercedes's Smart ForTwo Electric, which claims a range of 68 miles per charge and sells for $20,740 before incentives and discounts.

    3.纯电动

    纯电动车（EV）完全不需要汽油；它们用电池蓄电来驱动汽车。这种车三年前才推向大众市场，此后大家才开始慢慢接受它，现在对它的需求则开始日益增长，下至低端市场中现在售价已降为3万美元的日产聆风（Leaf，见上图），上到出乎意料大受欢迎、价格高达8万美元的特斯拉Model S。对续航里程的担心还是阻碍更多消费者购买它的主要原因，同时大城市外充电站数量极为有限也是一个很大的障碍。2013年市场上共有主要厂商生产的11款不同纯电动车在售，其中就有梅赛德斯出品的电动版斯玛特ForTwo（Smart ForTwo），它号称每充一次电的续航里程达到68英里，促销打折前的售价为20,740美元。

    4. Ethanol and flex fuel

    Thanks to the government's 2007 Renewable Fuels mandate requiring a certain amount of liquids made from renewable sources to be added to gasoline, ethanol made from corn has found its way into the nation's fuel supply. Some 84 car and truck models carry the designation "flex fuel," meaning they can run on mixtures that contain up to 85% ethanol. Lately, a backlash against ethanol use has developed as realization grows that ethanol contains less energy than gasoline, resulting in fewer miles per gallon, and takes a lot of energy to produce, which can lead to increased emissions of carbon dioxide. Opponents also argue that ethanol is unethical, because it diverts 40% of the corn grown from food supplies and drives up its cost.

    4.酒精和弹性燃料

    2007年，美国政府出台了《再生燃料法案》（Renewable Fuels），要求汽油中必须添加一定量的用再生能源制成的液体，这让用玉米加工的酒精得以进入美国的燃料供应体系。共有84种汽车或卡车使用了指定的“弹性燃料”，意味着它们的燃料最多可以包含85%的酒精。最近，针对酒精使用的批评正在抬头，因为大家逐渐认识到，酒精所含的能量比汽油少，导致每加仑燃油行驶的里程数减少，同时酒精生产却需要消耗大量的能量，而这又会导致二氧化碳排放增加。反对者还声称，使用酒精也是不道德的，因为它占用了食物供应中40%的玉米，同时推高了玉米的价格。

    5. Biodiesel

    Manufactured from vegetable oil, animal fats, or recycled restaurant grease, biodiesel raises the octane rating of conventional diesel fuel and burns more cleanly, in addition to being non-toxic and biodegradable. Biodiesel can be used in its pure form but is most often found in a blend with 80% conventional diesel fuel. Government regulations required 1.3 billion gallons of biodiesel to be produced in 2013. Biodiesel can be used in most vehicles that have conventional diesel engines without modification, among them Ford's (F,Fortune 500) F-250 Super Duty pickup.

    5. 生物柴油

    生物柴油用植物油、动物脂肪或饭店废弃油脂制成。除了无毒可降解之外，它还能提高传统柴油的辛烷值，燃烧更清洁。它可以单独使用，但经常会与80%的传统柴油混用。政府要求2013年生物柴油产量应达到13亿加仑。绝大多数搭载传统柴油引擎的汽车无需改装就能使用生物柴油，其中就包括福特汽车公司（Ford）的F-250超能（Super Duty）皮卡。

    6. Propane

    Ease of maintenance and reduced emissions have spurred the use of propane in light-vehicle fleets (police cars and school buses) as well as in heavy-duty trucks with such familiar nameplates as Kenworth and Peterbilt. More than 270,000 propane vehicles are now on the road. Also known as liquefied petroleum gas (LPG), propane is produced as a by-product of natural gas processing and crude oil refining. Despite a high octane rating and clean burning properties, propane costs about one-third less than gasoline. But it must be stored in a pressurized tank, and the propane refueling infrastructure is limited.

    6. 丙烷

    保养容易、排放减少，这两个优点已使轻型车队（警车和校车）以及大家熟知的肯沃思公司（Kenworth）和彼得比尔特公司（Peterbilt）的重载卡车都用上了丙烷。目前公路上奔驰的丙烷汽车已有27万辆。丙烷也叫液化石油气（LPG），是天然气加工和原油提纯的副产品。尽管拥有较高辛烷值和燃烧清洁的特性，丙烷的成本却比汽油还要便宜三分之一。不过它必须用压力罐储存，同时丙烷加注基础设施也很少。

    7. Liquefied and compressed natural gas

    Natural gas vehicles, operating on either liquefied or compressed gas, produce mileage similar to gasoline but burn more cleanly. The Energy Department estimates that some 112,000 vehicles powered by natural gas are currently in operation. Most are medium and heavy-duty trucks, but Honda (HMC) has offered a natural gas Civic (above) since 1998. It is slower than a gasoline one, has a limited range and refueling network, and costs thousands of dollars more. In its favor are cheaper prices for a fuel that is produced domestically and lower emissions.

    7. 液化或压缩天然气

    使用液化或压缩天然气的天然气汽车的续航里程和汽油车相仿，但燃烧更清洁。美国环保部（the Energy Department）估计，目前全美在用天然气汽车共有112,000辆。它们大多数是中型或重型卡车，但本田汽车（Honda）1998年就已经推出了天然气版的思域（Civic）。它比汽油版速度慢，行驶里程有限，加注网络也不完善，同时还要贵上好几千美元。有利于它推广的地方在于，这种燃料更便宜，在国内生产，排放也更低。

    8. Fuel cells

    Like a fictional El Dorado glimmering in the distance, affordable hydrogen-powered fuel cells have been an elusive goal for a generation of researchers. Hydrogen is appealing because it can be produced domestically and burns cleanly, and fuel cell vehicles are two or three times more efficient than gasoline-powered ones. What's held them back has been the cost of building the cells themselves and a network of fueling stations to distribute the hydrogen. As a result, small fleets of FCVs are being tested by manufacturers, but no fuel cell vehicles have reached the consumer market. Two notable models in limited tests: the Honda FCX Clarity, and the 2012 Mercedes-Benz F-cell (above), which gets 52 miles per kg of hydrogen (roughly equivalent to a gallon of gasoline).

    8. 燃料电池

    经济实惠的氢动力燃料电池对整整一代研究人员来说就像传说中在远方闪耀的金山（El Dorado）一样，是一个充满诱惑力的目标。氢气之所以这么吸引人，是因为它能在国内生产，而且燃烧清洁，同时燃料电池汽车的能效要比汽油车高两到三倍。妨碍它推广的主要因素是电池生产成本较高，加注氢气的站点也太少。结果，现在汽车厂商正在测试小型燃料电池车车队，但这类车还无法投放普通消费者市场。目前两款有名的车型正在接受极限测试：一个是本田FCX Clarity，另一个是2012款梅赛德斯奔驰F-Cell（见上图），这辆车每公斤氢气（大概相当于一加仑汽油）可行驶52英里。

    9. Solar

    In October, a car powered by the sun drove almost 2,000 miles across the Australian outback at an average speed of 56 miles per hour. Sounds perfect -- solar power is free and clean -- but there are a few caveats: The Dutch-engineered car (above) just carried a driver, travelled only during daylight hours, and used a small battery to get rolling. Is this the future? Probably not. The photovoltaic cells that capture the sunlight and convert it to electricity are expensive to produce, and the car is made from pricey lightweight materials like titanium composites. However, solar-powered vehicles might find limited use as commuter cars where they had an opportunity to recharge during the day, and some are used today as golf carts.

    9. 太阳能

    今年10月，一辆太阳能汽车以56英里的平均时速在澳大利亚内地行驶了2,000英里。听起来很完美——太阳能不用花钱，也十分清洁——但有几点必须注意：这辆由荷兰人打造的车（见上图）只载了一名驾驶者，只能在白天行驶，还要用一个小型电池才能开动。这就是未来的汽车吗？恐怕不是。用以捕捉阳光并将其转换为电能的光伏电池生产成本十分高昂，同时这辆车所用的钛合金这类轻型金属也非常昂贵。不过，太阳能车如果白天能充电，可能可用来当通勤车，比如有一些现在已用作高尔夫车了。

    10. Steam

    Between 1899 and 1905, the Stanley Steamer (above) outsold all gasoline-powered cars in the U.S. Steam engines had been in development since the early 18th century; gasoline was a baby by comparison. But internal combustion engines caught up quickly after they got self-starters, and steamers were doomed by having to carry around heavy boilers. Steam-powered vehicles still get attention because they can burn fuel like garbage, wood, and crude oil -- General Motors introduced two experimental ones in 1969 -- but they are relatively inefficient and very weighty. In 2009, a modern steam car broke the speed record set by a Stanley Steamer in 1906 when it exceeded 130 miles per hour, but it weighed more than three tons and contained more than two miles of steam tubing.

    10. 蒸汽

    1899年到1905年间，斯坦利蒸汽汽车（见上图）在美国的销量超过了所有汽油车。蒸汽机从18世纪早期就开始开发了，与之相比，当时的汽油引擎还只能算是个婴儿。但当内燃机装上自动启动装置后它们就迅速迎头赶上了，而蒸汽机由于必须携带沉重的锅炉则注定了要被淘汰。不过，由于蒸汽汽车能用垃圾、木柴和原油当燃料，它们还是引起了人们的关注——1969年通用汽车就推出过两款试验车型——但它们效率较低，也十分沉重。2009年，一辆现代蒸汽汽车以130英里的时速打破了斯坦利蒸汽汽车1906年创造的速度记录，但它重达三吨多，内部的蒸汽管道足有两英里多长。（财富中文网）

    译者：清远