Generating electricity with tomato waste

396.000 Tonnen Tomatenabfälle, die in Florida jährlich anfallen, können möglicherweise bald wie schon in einem Pilotprojekt als Basis für eine Brennstoffzelle, die elektrischen Strom erzeugt, dienen. A team of scientists is exploring an unusual source of electricity – damaged tomatoes that are unsuitable for sale at the grocery store. Their pilot project involves a biological-based fuel cell that uses tomato waste left over from harvests in Florida. The researchers presented their work at the 251st National Meeting & Exposition of the American Chemical Society (ACS). “We have found that spoiled and damaged tomatoes left over from harvest can be a particularly powerful source of energy when used in a biological or microbial electrochemical cell,” says Namita Shrestha, who is working on the project. “The process also helps purify the tomato-contaminated solid waste and associated waste water.” Shrestha is a graduate student in the lab of Venkataramana Gadhamshetty, Ph.D., P. E ., at the South Dakota School of Mines & Technology. They are collaborating on this project with Alex Fogg, an undergraduate chemistry major at Princeton University. Other project collaborators include Daniel Franco, Joseph Wilder and Simeon Komisar, Ph.D., at Florida Gulf Coast University. Tomatoes are a key crop in Florida, notes Gadhamshetty. He stresses that the project is important to the state because Florida generates 396,000 tons of tomato waste every year, but lacks a good treatment process. Gadhamshetty began working on the topic as a professor at Florida Gulf Coast University. “We wanted to find a way to treat this waste that, when dumped in landfills, can produce methane – a powerful greenhouse gas – and when dumped in water bodies, can create major water treatment problems.” The team developed a microbial electrochemical cell that can exploit tomato waste to generate electric current. Shrestha explains, “Microbial electrochemical cells use bacteria to break down and oxidize organic material in defective tomatoes.” The oxidation process, triggered by the bacteria interacting with tomato waste, releases electrons that are captured in the fuel cell and become a source of electricity. The natural lycopene pigment in tomatoes, the researchers have found, is an excellent mediator to encourage the generation of electrical charges from the damaged fruits. Some of their results proved to be counterintuitive. “Typical biotechnological applications require, or at least perform better, when using pure chemicals, compared to wastes,” Gadhamshetty notes. “However, we found that electrical performance using defective tomatoes was equal or better than using pure substrates. These wastes can be a rich source of indigenous redox mediators and carbon, as well as electrons.” At the moment, the power output from their device is quite small: 10 milligrams of tomato waste can result in 0.3 watts of electricity. But the researchers note that with an expected scale up and more research, electrical output could be increased by several orders of magnitude. According to calculations by Shrestha, there is theoretically enough tomato waste generated in Florida each year to meet Disney World’s electricity demand for 90 days, using an optimized biological fuel cell.
They plan to improve the cell by determining which of its parts – electrode, electricity-producing bacteria, biological film, wiring – are resisting the flow of electricity. Then they will tweak or replace that part.

Source: American Chemical Society; Science Daily Vocabulary

according to	laut, zufolge
associated	verbunden, zugeordnet, assoziiert
calculation	Rechnung
capture	erfassen, fangen, erbeuten
contaminate	kontaminieren, verunreinigen
counterintuitive	nicht eingängig, nicht intuitiv, kontraintuitiv
crop	Ernte, Ernteertrag
damaged	beschädigt
determine	bestimmen
device	Gerät
dump	entladen, verklappen, entsorgen, auskippen
encourage	ermutigen
enough	genügend, ausreichend
exploit	ausnutzen
generate	generieren, erzeugen
graduate student	Diplomstudent, Absolvent, Doktorand
grocery store	Lebensmittelladen
harvest	Ernte
however	jedoch
improve	verbessern
indigenous	heimisch, indigen
lab (= laboratory)	Labor
lack	mangeln, fehlen
landfill	(Müll-)Deponie
lycopene	Lycopin, Leukopin (in Tomaten und Hagebutten vorkommender Stoff; verleiht die rote Farbe)
microbial	mikrobiell, mikrobisch
order of magnitude	Größenordnung
P. E. (USA = professional engineer)	lizensierter Ingenieur
Ph.D.	Doktortitel, Dr.
prove to be	sich erweisen als, sich zeigen als
purify	reinigen, läutern
redox mediator	Redox-Mediator löst eine Redox- bzw. Reduktions-Oxidations-Reaktion aus, bei der ein Reaktionspartner Elektronen auf den andern überträgt)
replace	ersetzen
require	benötigen, erfordern
researcher	Forscher
resist	widerstehen, standhalten
scale up	vergrößern, heraufsetzen
solid waste	Feststoffabfall
spoiled	verdorben
treatment	Behandlung, Bearbeitung
trigger	anstoßen, auslösen, bewirken
tweak	zwicken, hier: optimieren
undergraduate chemistry major	Chemiestudent
unsuitable for sale	zum Verkauf ungeeignet
waste    wiring	Abfall Verkabelung, Verdrahtung

Autor: P. Zillmer Lesen Sie den Artikel in unserem Facharchiv.