石油设备网讯 据今日油价8月4日报道，就碳排放而言，天然气相对于另外两种化石燃料——煤和原油——的优势似乎是毋庸置疑的。天然气是一种碳强度很低的燃料，这引起了人们将它作为石油衍生液体燃料替代品的关注。然而，也面临着一些挑战，现在一组中国科学家团队称困难已经接近解决。
天然气主要由甲烷和丙烷组成。甲烷是工业界和环保主义者之间的一个症结，因为它是一种比碳更强大的温室气体。但如果这种甲烷可以转化为燃料，就将是一个双赢的局面，因为燃烧天然气的副产品是水蒸气和二氧化碳。
在一篇关于中国科学家的突破性进展的文章的报道中指出，将天然气加工成液体燃料是一件棘手的事情。这一过程包括将氢氧化合物引入气体中，重新排列其原子。然而，并不是所有的原子对氧和氢的反应速度都是一样的，这可能会破坏作为燃料的乙醇。
本质上，中国研究人员所做的是加强对转化过程的控制，这使他们能够控制甲烷和丙烷中碳和氢重新排列形成酒精分子的速度。该团队表示，这将使天然气衍生燃料的生产更加经济。
天然气作为汽油和柴油替代品的潜力不应被低估，尤其是在目前天然气储量丰富的情况下，尤其是在美国，这多亏了页岩气革命。
一位来自阿贡国家实验室的工程师表示：“我们的结论是，天然气作为一种运输燃料，既具有充足的储量优势，又具有成本优势，这是一个强有力的理由，使人们关注这项技术，把它作为美国能源安全的一个真正的游戏规则改变者。”七年前，奥巴马政府启动了一项3000万美元的计划，用于研究如何让天然气成为更受欢迎的汽车燃料。
然而，自那时以来，项目进展甚微，部分原因是其转换过程具有挑战性。一种更简单的压缩天然气(cng)已经用于一些国家的公共交通工具和乘用车中，但它尚未成为汽油和柴油的真正挑战者。虽然CNG更便宜、更高效，但燃烧速度更快，它需要更大的油箱，扭矩也比汽油和柴油小。
这就是液态天然气燃料的潜力所在。在液态形式下，天然气可能比石油衍生燃料更具竞争力，但只有在天然气转化为液态的挑战被克服之后。
科学家们正在研究这个问题，这是件好事。如果研究成功，最终可能会促使石油生产商寻找减少天然气燃除的方法。美国去年的天然气燃除量在页岩气热潮的推动下增长了48%。在未来的某一时刻，大量的甲烷可以被收集并转化为燃料，而燃烧这些甲烷却没有任何收益。
洪伟立 摘译自 今日油价
原文如下：
Turning Natural Gas Into Fuel Just Became Cheaper
The advantages of natural gas over the other two fossil fuels—coal and crude oil—seem to be indisputable when it comes to carbon emissions. Natural gas is a much less carbon-intensive fuel, which has drawn attention to it as an alternative to oil-derived liquid fuels. However, there have been challenges that now a team of Chinese scientists claim to have come closer to solving.
Natural gas consists mostly of methane and some propane. Methane is a sticking point between the industry and environmentalists because it is a much more powerful greenhouse gas than carbon. But if this methane can be turned into fuel it would be a win-win situation since the byproducts of burning natural gas are water vapors and carbon dioxide.
Processing natural gas into liquid fuel is tricky, Phys.org reports in an article on the Chinese scientists’ breakthrough. This processing involves the introduction of oxygen-hydrogen compounds into the gas, which rearranges its atoms. However, not all atoms react to the oxygen and the hydrogen at the same speed and this could ruin the resulting alcohol that would be used as a fuel.
What the Chinese researchers did, essentially, was increase their control over the conversion process, which allowed them to manipulate the speed at which the carbon and hydrogen in the methane and propane rearranged themselves to create alcohol molecules. This, according to the team, would make gas-derived fuel more economical to produce.
The potential of natural gas as a replacement for gasoline and diesel should not be underestimated especially amid the current abundance of natural gas, notably in the United States, thanks to the shale revolution.
“Our conclusion is that natural gas as a transportation fuel has both adequate abundance and cost advantages that make a strong case to focus interest in the technology as a real game changer in U.S. energy security.” This is what one engineer from the Argonne National Laboratory told Talking Points Memo, a news outlet, seven years ago, a few months after the Obama government launched a US$30-million grant program for research into making natural gas a more popular fuel for vehicles.
Since then, however, little progress has been made and part of the reason is that challenging conversion process. A simpler form of natural gas—compressed natural gas or CNG—is already in use for some countries’ public transport vehicles and also in passenger vehicles, but it has yet to become a real challenger for gasoline and diesel. While cheaper and more efficient, CNG gets burned up more quickly, it requires a larger tank, and has less torque than gasoline and diesel.
This is where the potential of liquid natural gas fuels lies. In liquid form, natural gas would probably be more competitive with oil-derived fuels but only after the challenges with its conversion into liquid are overcome.
It’s a positive that scientists are working on this. If research is successful it could eventually motivate oil producers to seek ways to reduce gas flaring, which in the U.S. last year grew by 48 percent driven by the shale boom. That’s a lot of methane being burned for no revenues when it could be captured and turned into fuel at some point in the future.
