A garden hose, a tin can, duct tape, metal piping, kitchen cleaner, and gasoline: That is all television icon MacGyver needed to make a flame-thrower to ward off a swarm of killer ants. In the real world, technologies that are affordable and practical are not so simple to create, but they can make a huge impact on people's lives. Instead of calling on complex solutions (reliant on engines and imported resources) for low-tech problems (such as cooking and lighting), some researchers are now developing what they call "confluent" technologies—ones that are effective, affordable, and sustainable for use in the developing world. Here's a look at the latest breakthroughs:

1 Energy in a Bucket of Dirt
Who needs nickel cadmium batteries or coal plants for electricity when you have soil? A Harvard team of faculty and African students have tapped into soil-dwelling microbes in order to provide electricity for families in Tanzania. When the microbes found in the soil digest organic materials, they naturally produce a small current, which can be harnessed with a simple device consisting of two electrodes and a small circuit board. One trash-barrel-sized unit filled with soil can produce enough electricity to light two bedrooms for a decade or more, says Harvard biology professor Peter Girguis. While each unit currently costs about $50, the team is testing new materials that would drive the price down to $7.

2 Micro-Hydroelectric Power
Hilly land streaked with small streams makes an ideal spot for micro-hydroelectric power generators, each of which requires a meager water flow of just three gallons per second to turn. (To put this in perspective, the Mississippi's average flow at New Orleans is about 4.4 million gallons per second.) The Appropriate Infrastructure Development Group (AIDG) has helped to build three systems in Guatemala, and more communities are now saving up money for local installations.

3 Biodigesters
At the end of Back to the Future, a little bit of garbage is all Doc Brown needs to fuel his DeLorean time machine. Biodigesters won’t quite generate "1.21 jigawatts" of power (as Doc's Mr. Fusion device seemed to), but they can create fuel for heating, cooking, and electricity while reducing waste and water contamination. In the salchicha-type biodigester (salchicha means "sausage" in Spanish), bacteria break down waste in a 15-to-30-foot-long polyethylene tube and release methane, which is captured and piped to a stove. The digested waste can then be used as a fertilizer. Biodigesters have been around since the 1870s, but current efforts focus on producing them on a larger scale. An award-winning system installed in Rwandan prisons reduced the need for firewood by half.

4 Wind Power on $2 a Day
Who said wind turbines have to spin? Shawn Frayne, founder of Humdinger Wind Energy, developed a turbine-less generator that harnesses energy from the rapid wind-induced vibration (50 cycles per second) of a seven-to-ten-foot flap of taffeta fabric. This is the same phenomenon—aeroelastic flutter—that civil engineers try to eliminate so bridges don’t sway in the wind, and on a small scale, it greatly increases the efficiency of capturing power from wind for a very small cost, says Frayne. "For people making a dollar or two a day, it could be in the realm of possibility to have electricity," says Peter Haas of AIDG, who is helping Frayne test the generators in Guatemala. Depending on wind conditions, the generators can be positioned to power efficient lights in a few rooms on small electrical grids. Frayne hopes to make the product available within a few years.

5 Sunlight Stored in LEDs
In rural Indian Homes, kerosene lamps are ubiquitous, posing health concerns from fumes as well as a fire risk. Solar-charged lights designed by Patrick Walsh, founder of Greenlight Planet, are one solution to this problem. The lights run for four hours on their brightest setting after charging in the sun all day. The lights also reduce fuel costs for families and pay for themselves in just one year. After testing the market with 20 lamps, Walsh is now scaling up production.

6 Solar Water Heater
Solar water heaters are generally expensive (they can cost $400–$1,000), barring easy access to hot water for many who are far from an electric grid. But engineer Ashok Gadgil at the University of California, Berkeley, working with AIDG, cut back on materials and came up with a solar heater that costs $100. It can produce 26 gallons of water warmed to 104 degrees Fahrenheit by 4 p.m. each day—enough for four showers. Tests are ongoing in Guatemala, after which the team plans to fine-tune the design and begin distribution.

7 Pedal-Powered Grid
People who live off the grid in rural corners of the world may soon have a new source of energy: 12-volt batteries charged by pedaling. Using a simple alternator, six hours of pedaling can create and store enough electrical energy in batteries to light about six Homes for 30 days (in areas where people use less electricity than in the U.S.). Dissigno, the San Francisco–based company that distributes the devices, has one prototype up and running in Haiti and next hopes to install a "grid" in Tanzania connected by a network of pedalers instead of power lines.

8 Sugarcane Charcoal
In Haiti, most people cook using charcoal made from wood, but the country is now 98 percent deforested due largely to mismanagement of resources. MIT students and lecturer Amy Smith turned to widely available bagasse, the stalks of sugarcane plants left after squeezing the sugar out, and created a charcoal replacement by burning, compressing, and mixing the material with a binding agent. The team is currently looking to train prospective entrepreneurs interested in producing and distributing the product.

9 Irrigation by Foot
Most African farmers rely on seasonal rainfall, having no other means of irrigation for crops. So Martin Fisher, the CEO of KickStart International, came up with a device you can pump with your feet that pulls water from 30 feet underground with enough pressure to irrigate up to two acres of land. This enables more frequent harvests of high-value crops like vegetables rather than grains. In Africa, more than 65,000 such pumps are currently in use. Fisher won the 2008 Lemelson-MIT Award for Sustainability for the invention.

10 Chlorine from Salt
For the roughly 1.2 billion people lacking clean water, a bit of chlorine could go a long way toward providing it. Using two ounces of salt water and some muscle, University of Iowa engineering professor Craig Just can make enough bleach to kill the disease-causing microorganisms in five gallons of water. His trick: a hand-cranked device that generates electricity to zap water molecules, splitting them and joining them with chlorine atoms from salt. Just and his students plan to test a prototype in Ghana and Honduras next year.

一个浇花胶皮管，锡制罐子，胶带，金属管，厨房清洁剂和汽油：那是按电视图像百战天龙所需而制的火焰喷射器来抵挡虫子和蚂蚁杀手。在现实世界中，所普及的和实际应用的科学技术并不是这么简单就能创造的，但他们却能给人们的生活带来巨大的影响。代替那些解决低科技含量问题(像做饭点火和照明)而用复杂解决办法（依靠发动机和进口材料）的行业，一些发明家现在正在发明一种他们所谓的“混合”技术—一种高效的，能普及的，实用的技术来应用到发展中的世界。下面就来看这些最新的突破：

1  垃圾桶中的能源

当你有污物时谁会想到利用镍镉电池和煤炭工厂来进行发电？一个来自哈佛的学院队伍和来自非洲的学生们正钻研于污物分解微生物的研究中来为坦桑尼亚的居民提供能源。当发现于土壤中的微生物分解有机物质时，它们会自然产生一股小额电流，可以被一个由两个电极组成的简单装置和一个小型电路板所利用。一个装满污物的有尺寸大小的垃圾桶装置能产生足够可以用来为两间卧室照明长达十年或更长的时间的能源，哈佛生物教授Peter Girguis这样说。而每一套装置目前要花费大概五十美元，这个团队正在研究新型材料使价格能降到7美元。

2 微型水力发电厂
带有小溪的多丘的山地是安装微型水利发电设备的理想之地，每个仅需每秒三加仑水量的微弱水流即可运转。(从投入的角度看，密西西比河在新奥尔良的平均水流量大约为每秒4.4百万加仑。适当的基础设施发展集团已经帮助在危地马拉建立了三套系统，更多社区正节省钱财来用于当地的设施安装。

 3 生物降解
在影片回到未来的结尾, Doc Brown所需的就是一点垃圾来给他的德罗宁时光机提供燃料.生物降解不会产生＂1.21瓦＂的动力(如Doc's Mr熔解装置所示),但它们能生成燃料来加热,做饭并且能发电同时还减少废物排放和水污染.在这个salchicha型的生物降解中(salchicha在西班牙语中的意思是香肠),细菌在一个15-30英尺长的聚乙烯试管中分解废物并且释放甲烷,获取后并将其通过管子送到炉子中.分解后的废物可以被用作肥料.生物降解技术自从19世纪70年代就被广泛使用,但目前的努力正致力于大规模的生产.一个屡获殊荣的装置被安放在卢安达监狱中从而减少了一半对木柴的需求.

4 每天2美元的风力
谁说风涡轮机就得自转? Humdinger风动能的创始人Shawn Frayne,发明了一个无风涡轮发动机,能从一个利用7-10英尺的塔夫绸织物拍打的快速风感应装置的震动中(每秒50转)获取能量.这和气动弹性颤震是同一种现象—国内的工程师们正试着消除在风中不摆动的桥接器,并且在一个较小的程度上,它逐渐提高了用低成本获取风能的效率, Frayne说.“人们一天花1-2美元，就有用电的可能性，” AIDG的彼得哈斯这样说，他为在危地马拉做发动机实验的Frayne提供了帮助。依靠风自身的条件，发动机可以被安置在小的电网上为数间屋子提供照明。Frayne希望这个产品几年之内就可为人们使用。

5  用发光二极管储存阳光
在偏远的印第安人家庭中,煤油灯无处不在,煤烟对人的健康带来威胁并且有火灾隐患.由绿光星球的创始人派屈克沃尔什设计的太阳能充电灯,对此问题是一种解决的办法.这种灯在一整天的阳光下充足电后可以在最亮的设置下连续点四个小时.这种灯也能减少家庭用煤的成本并且一年后就可以买到它们.在市场上投放了20盏灯作为实验后,沃尔什正按比例加大生产量.

6 太阳能热水器
太阳能热水器通常来讲很贵（要花费400美元至1000美元），除了那些没有电网还能轻易获得热水的人。但位于伯克莱的加州大学工程师Ashok Gadgil，和AIDG合作，消减材料的成本费用并制造出只需100美元的太阳能热水器．它能在每天下午四点之前加热26加仑的水至华氏温度104度－足够淋浴四个小时.实验正在危地马拉开展,随后团队将对设计进行微调并开始经售.

7 踏板电网
住在世界偏远地区远离电网的居民不久将会拥有一种新型能源：用脚踏板来充电的12瓦特的电池。使用这个操作简单的替代品，六个小时的脚踏即可产生并能储存供六个家庭使用三十天的电（这些地方的居民比起美国居民用电量更少）。Dissigno，这家旧金山的公司经售这些装置，有一套原型并在海地运作并且下一步希望在坦桑尼亚安装一个＂电网＂用脚踏装置来代替电线来连接.

8  甘蔗木炭
在海地，大部分居民用木头制成的木炭来做饭，但是这个国家现在98%的森林由于对资源的管理不善而遭到破坏。麻省理工学院的学生和讲师艾米史密斯将研究转向了广泛种植的甘蔗。甘蔗的茎能在榨干糖分后经过烘烤，挤压，用一种粘合剂混合其它物质然后成为木炭的替代品。这个团队目前正在寻找培养有前景的企业来生产并推广这种产品。

9用脚来灌溉
大部分非洲的农民都依赖季节性的降雨，没有其他灌溉农作物的手段。所以马丁菲斯而，KickStart国际的首席执行官，发明了一种装置可以用脚施加足够的压力把离地30尺的地下水抽上来灌溉两英亩地。这使得许多像蔬菜这样的高产农作物比谷物类收成更多。在非洲，大约有65000多这样的抽水机正在使用。菲斯而赢得了由麻省理工学院颁发的发明可持续大奖。

10  盐中的氯
 大约有12亿的人缺少干净的水，到能提供足够的氯还要花很长的时间。用两盎司的盐水和一些压力，衣阿华州大学的动力专家克莱格就能用足够的漂白剂来杀死五加仑水中的致病微生物。他的办法是：用一个手动曲柄装置来产生电流快速震击水分子，分解它们同时用盐中的氯分子来连接它们。他和他的学生们打算明年在加纳和洪都拉斯做一个实验模型。