Science and Technology
Solar heat for oil wells
Mirrors in glasshouses can be used to heat stones
THERE is a lot of energy from ancient sunshine stored in the oil that sits below the deserts of Oman.
There is also a lot of sunshine hitting those deserts today.
A new wrinkle to an established technology should allow some of that current sunshine to be employed to get at more of the ancient stuff.
Using heat-in the form of steam-to liberate disobligingly thick and gunky oil which would otherwise stay in the ground is nothing new.
Such enhanced-recovery techniques date back to the 1950s and 40% of California's oil production now depends on steaming subterranean rocks in this way.
The steam, however, is made by burning other fossil fuels-normally natural gas-and because heating rock takes a lot of steam, making that steam takes a lot of money.
然而, 蒸汽是需要燃烧其他燃料来产生的--一般来说是天然气--因为加热岩石需要很多的蒸气, 那么制造这些蒸汽的成本就会很高。
It also adds to the oil's climate footprint.
The amount of gas used means that a barrel of Californian heavy oil gives the stuff from Canada's tar sands a run for its money in terms of associated greenhouse-gas emissions.
GlassPoint, a small Californian company, thinks it can make steam for oil recovery more cleanly and cheaply by using sunshine to do the heating.
This sounds surprising.
Solar-thermal power stations, which employ mirrors to concentrate sunlight on boilers and thus raise steam to generate electricity by turning turbines, are far from cheap compared with gas-fired stations.
But solar-thermal electricity faces exacting challenges.
To feed a turbine you need particularly pure steam, which can be a problem if you are in a desert.
为了能够推动涡轮, 你需要特别纯净的蒸气, 如果处于沙漠地带那么这将是个问题。
And to get the most out of the system you need the steam to be both very hot indeed and available in copious amounts.
Oil wells, GlassPoint's founders noticed, are far less demanding consumers in these respects.
GlassPoint的创建者们发现, 在这些方面, 油井就不是那么挑剔的消费者。
The steam used can be comparatively dirty. Nor does it have to be infernally hot.
And even a small amount of it, added to an existing gas-based recovery process, can make a useful contribution.
There are, though, disadvantages to having to work in an oilfield.
People building solar-thermal power stations prefer sites low in dust.
Those serving the oil industry must go where the rigs are, however dusty and mucky the air.
GlassPoint seems to have found a neat solution to this: it puts its mirrors indoors.
Greenhouses are easy to buy, quick to erect and, thanks to off-the-shelf kit designed for the purpose, simple to keep clean, too.
温室容易购买, 并且由于是普遍的套件设计, 所以安装快速, 保洁简单。
Moreover, sheltering the mirrors from the wind allows those mirrors to be a lot lighter, making them both cheap to build and ship, and easier to turn in order to follow the sun.
另外, 由于镜子避免了暴露在风中所以镜子可以更轻便, 使得镜子的生产和运输成本更低并且也更容易随着太阳的位置变动方向。
GlassPoint's boss, Rod MacGregor, thinks that taking capital costs and the lifetime of the plant into account his firm can produce steam at $3.78 per million British thermal units (btu), which is $3.58 a gigajoule.
GlassPoint的老板Rod MacGregor认为如果把资本成本和工厂的生命期算在内的话, 他的公司可以以每百万英热单位(btu)3.78美金的价格生产蒸汽, 即十亿焦耳3.58美金。
Steam from gas comes in at $5.79 per million btu.
A pilot project in California, he says, has been producing steam as intended since the beginning of the year.
And the company has now signed a deal with Petroleum Development Oman for 7 megawatts of plant-a 16,000-square-metre greenhouse providing some 57 billion btu of steam a year.
现在公司正在为Petroleum Development Oman设计一个年产7百万瓦特的工厂--一个16000平方米温室, 每年生产大概570亿英热单位的蒸气。
If it pans out, the technology could spread fast.
Mr MacGregor expects Oman to be using 200 trillion btu of steam a year for oil recovery by 2015.
Not all of that steam could be solar, but a system which used high-pressure solar steam during the day and low-pressure gas-generated steam by night, to keep the pipes hot, might get 80% of its power from the sun.
尽管不是所有的蒸气都是太阳能生产的, 但是白天使用高压太阳能生产蒸汽, 晚上使用低压燃气生产蒸气来维持管道高温的系统可能其80%的能源都来自于太阳。
That would free up a lot of gas for export-or for turning into petrochemicals.
Enhanced oil recovery currently uses a quite remarkable amount of energy: 1.7 quadrillion btu of gas around the world every year, according to GlassPoint.
当下驱油所使用的能源总量惊人: 根据GlassPoint统计, 每年全球在这方面使用的燃气大约为1.7千兆英热单位。
Not all of that is in sunny places, but there are many deserts besides Oman's that have oil beneath them.
The paradoxical possibility, then, is that solar-thermal technology might end up producing a lot more oil than electricity in the years to come.