开发出实用的微生物燃料电池

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目前全世界正面临着能源危机，科学家们正在寻找化石燃料可能的替代能源。美国威斯康星-麦迪逊大学的一个交叉学科研究小组正在研究通过细菌的光合作用产生持续电流的技术。

??微生物燃料电池的概念已经提出将近三十年了，当时一个英国研究人员在碳水化合物中培养细菌的过程中，连接两个电极时，观测到了微弱的电流。土木与环境工程教授Daniel Noguera说：“尽管有一些研究小组一直在研究微生物燃料电池，但是之前它还只处于实验室研究阶段。但是现在微生物燃料电池的研究已经逐渐成形，有望成为一种替代能源。”

??Noguera与土木与环境工程教授Marc Anderson、助理教授Trina McMahon，细菌学教授Timothy Donohue，研究员Isabel Tejedor-Anderson，已经研究生Yun Kyung Cho和Rodolfo Perez合作发展出一种能在污水处理厂应用的大规模微生物燃料电池系统。McMahon说：“事实上，光合作用细菌可以有效地从它们的食物中分离出能量。微生物可以从有机废物的剥离电子，然后形成电流。利用我们先进的电子提取技术，我们可以使这个转化过程更有效的进行。”

??Donohue说：“这可能是一项双赢的技术。既可以利用‘免费’的太阳能资源产生电流，又能同时处理废物。”他还说，利用光合作用细菌的好处是可以在利用太阳能的同时产生额外的电流。

??目前，研究人员们把微生物封装在密闭的无氧测试管中，测试管的形状被做成类似电路的回路。当处理废物时，先把有机废水通入管中，作为副产品电子向阳极移动，然后通过回路流到阴极。另外一种副产品质子通过一块离子交换膜流到阴极。在阴极中，电子和质子与氧气发生反应形成水。

??一块微生物燃料电池理论上最大可以产生1.2伏特电压。但是可以像电池一样把足够多的燃料电池并联和串联起来产生足够高的电压来作为一种有实际应用的电源。Noguera说：“目前我们面临的挑战是怎样把这种小的实验微生物燃料电池做大，使它能应用于家庭、农场或大型污水处理厂。”目前，该研究小组正在利用他们在材料科学、细菌学和环境工程方面的优势来最优化微生物燃料电池的结构。


英文原文：

Researchers harness the power of bacteria

The concept of such so-called microbial fuel cells emerged nearly three decades ago when an English researcher fed carbohydrates to a bacteria culture, connected electrodes and produced tiny amounts of electricity. Although a few research groups are studying them, microbial fuel cells largely live in the realm of laboratory entertainment and high-school science experiments, says civil and environmental engineering Professor Daniel Noguera. \"Now, the idea is taking shape that this could become a real alternative source for energy,\" he says.

Noguera, civil and environmental engineering Professor Marc Anderson, civil and environmental engineering Assistant Professor Trina McMahon, bacteriology Professor Timothy Donohue, senior scientist Isabel Tejedor-Anderson and graduate students Yun Kyung Cho and Rodolfo Perez hope to develop a large-scale microbial fuel cell system for use in wastewater treatment plants. \"It's inexpensive,\" says Noguera of the nutrient-rich wastewater food source. \"We treat the wastewater anyway, so you are using a lot of energy to do that.\"

In nature, says McMahon, photosynthetic bacteria effectively extract energy from their food — and microbial fuel cells capitalize on that efficiency. \"By having the microbes strip the electrons out of the organic waste, and turning that into electricity, then we can make a process of conversion more efficient,\" she says. \"And they're very good at doing that-much better than we are with our high-tech extraction methods.\"

Through machinery such as plants, photosynthetic bacteria harvest solar energy. They also make products to power microbial fuel cells. \"In many ways, this is the best of both worlds — generating electricity from a 'free' energy source like sunlight and removing wastes at the same time,\" says Donohue. \"The trick is to bring ideas from different disciplines to develop biorefineries and fuel cells that take advantage of the capabilities of photosynthetic bacteria.\"

The benefit of using photosynthetic bacteria, he says, is that solar-powered microbial fuel cells can generate additional electricity when sunlight is available.

Currently, the microbes live in sealed, oxygen-free test tubes configured to resemble an electrical circuit. Known as a microbial fuel cell, this environment tricks the organisms into delivering byproducts of their wastewater dinner — in this case, extra electrons — to an anode, where they travel through a circuit toward a cathode. Protons, another byproduct, pass through an ion-exchange membrane en route to the cathode. There, the electrons and protons react with oxygen to form water.

One microbial fuel cell produces a theoretical maximum of 1.2 volts; however, like a battery, several connected fuel cells could generate enough voltage to be useful power sources. \"The challenge is thinking about how to scale this up from the little toys we have in the lab to something that works in the home, on farms, or is as large as a wastewater treatment plant,\" says Noguera.

For now, the researchers are combining their expertise in materials science, bacteriology and engineering to optimize fuel cell configuration.