Table of Contents
Chapter 1. 2
1. ENERGY NEEDS AND
1.2. MFCs AND
ENERGY SUSTAINABILITY OF THE WATER INFRASTURCTURE: 3
Chapter 2. 4
LITERATURE REVIEW… 4
2. MICROBES: 4
2.1. MICROBIAL FUEL
2.2. TYPES OF MFCs: 4
2.2.1. Mediated: 4
2.2.2. Mediator-free: 5
2.2.3. Soil Based: 5
2.3. PRINCIPLE OF
MICROBIAL FUEL CELL: 6
2.4. MFC DESIGN: 7
MFC Design: 7
2.4.2. Single-chamber MFC Design. 7
OF MFCs: 7
2.5.1. Generation of
2.5.2. Waste Water
Chapter 3. 9
3. COMPONENTS. 9
3.1. CONSTRUCTION.. 9
3.2. PROCEDURE. 12
3.3. POWER GENERATION.. 13
Chapter 4. 14
RESULT AND DISCUSSIONS. 14
4. RESULTS. 14
4.1. DISCUSSION.. 14
Chapter 5. 15
5. LIMITATIONS. 15
5.1. RECOMMENDATIONS. 15
5.2. ENERGY AND THE CHALLENGE OF GLOBAL CLIMATE CHANGE. 15
consumption is increasing day by day within the world. These energy sources
include fossil fuel, renewable sources and nuclear sources in which non-renewable
sources of energy, which include enormous portion of energy consumption, could
be categorized into major classification; nuclear and fossil. These energy sources
are causing global warming and climate change. Fossil fuels have been formed
from the organic remains of long-dead plants and animals. They contain a high
percentage of carbon and hydrocarbons. Primary sources of energy used around
the world include petroleum, coal, and natural gas, all fossil fuels. With
energy needs increasing, the production and use of these fossil fuels create
serious environmental concerns. Until a global movement for renewable energy is
successful, the negative effects of fossil fuel will continue.
we know that we urgently need a alternative source of energy. We are currently
using fossil fuel which is unsustainable for us and for our environment that is
why many searches are being conducted for replacement of energy source. And it
does not appear that one replacement will fulfill the whole energy necessity.
Some countries around the world have made remarkable efforts to find a piece of
cogent solution like Renewable sources, solar energy and energy produced by
wind and water. These efforts proposed a new discovery of Microbial Fuel cell
in which bacteria can be used to produce electricity from waste water and
renewable biomass. This discovery has gained much attention due to its
uniqueness. It is the one of the 50 top most inventions of 2009 in Time
magazine. This lead to increase interest in MFC and raise number of
publications. These systems are very adaptable and provide much energy in
sustainable way but the major improvement was widespread of this application. MFCs
use active microorganisms as a catalyst in anaerobic mode for the production of
bioelectricity. Electrical current produced by bacteria was first observed by
Potter in 1911 and its research domain became wider in 1999s. The microbial
fuel cell is a bio-electrical system in which bacteria is used to convert
organic material into electricity.
Soil is filled with bacteria that
produce electricity when they are placed in Microbial Fuel Cell (MFC). Such
bacteria filled soil is found almost everywhere on earth. An MFC has two
electrodes and an area that separates that electrode (called a membrane). For
an MFC to work properly, electricity in form of electrons must flow into one
electrode and leave the other. Some types of soil bacteria can help generate electricity;
these are known as electrogenic bacteria, includes the shewanella species that
can be found in almost all soil types. And the geobacter species which prefer
living in soil deep underground or even under the ocean where no oxygen is
present. The soil bacteria eat the nutrients in the soil, sugars, and in turn
produce electrons that are released back into the soil, which can be used to
create electricity in the form of energy.
1.2. MFCs AND ENERGY SUSTAINABILITY OF THE WATER INFRASTURCTURE:
and water are intricately connected. Energy is itself required to make water
resources available for human use and consumption (including irrigation)
through pumping, transportation, treatment, and desalination. Over two billion
people on the planet lack adequate sanitation and one billion do not have
access to portable water. Energy demands for conventional water and waste water
processes as a large part of the problem. We serve our most part of produced
electricity in the treatments of water. So greatly need a new sustainable
source of energy production in the form of MFCs. And also MFCs are used in
water treatment to harvest energy utilizing anaerobic digestion.
The process can also reduce pathogen.
review will provide handy information about MFCs. It will reveal the relevant
information about the technology used in Microbial Fuel Cell. It will let the
reader to understand its design and function.
order to understand the fundamental principle of Microbial fuel cell it is
important to have information about the microorganisms. Bacteria are the major
microbes which are involved in this process. Bacteria breakdown organic matter
and release energy in the process. Some bacteria have the ability to generate
electricity and to transfer electrons effectively to anode. The bacteria which
have this ability are known as “Exoelectrogen”. Exoelectrogen have the ability
to generate electricity in microbial fuel cells by extracellular electron
transfer to anode. It directly transfers electrons to a chemical or material
that is not immediate electron acceptor.
electrogens can be sourced in sand, water and many other sources. But here we
are using soil as a source.
fuel cell is a bio-electrical system in which bacteria is used to convert
organic material into electricity.
are two types of MFCs:
2.2.1. Mediated: In this type of
microbial cells a mediator is used o transfer electrons to electrode. Examples
of commonly used mediators are thionine, methyl blue and neutral red etc.
2.2.2. Mediator-free: Mediator free MFCs
used electrochemically active microbes (mostly bacteria) to transfer electrons
directly to electrode. Mediator-free cells can directly obtain energy from
certain plants. This is known as plant microbial fuel cell. Possible plants
include sweet grass, tomatoes and algae etc. It can provide ecological
1.2: A plant
microbial fuel cell
2.2.3. Soil Based: In soil based MFC,
soil acts as a nutrient rich anodic media, the inoculums and proton exchange
membrane. The anode is placed at the bottom whereas cathode is placed at the
top and is exposed to the air. Soil is filled with diverse microbes, including
electrogenic bacteria, is full of complex sugars and other nutrients obtained
from plants and animal material decay.
2.3: Soil based MFC
OF MICROBIAL FUEL CELL:
fuel cells (MFCs) are electrochemical devices that use the metabolic activity
of microorganisms to oxidize fuels, generating current by direct or mediated
electron transfer to electrodes.” K. Rabaey and W. Verstraete, page 291–298,
Jun. 2005. The device consists of anode, cathode, proton exchange membrane and
an external circuit. The MFC convert biodegradable substrate directly into
electricity. Anode holds the bacteria and the organic matter in an anaerobic
environment. Cathode is exposed to air. Bacteria generate protons and electrons
as organic substance converts to energy. Microbes use this energy for growth.
The electrons are transferred directly to the anode (if mediator-free MFC) and
then to copper electrode via conduction.
bacteria are unable to transfer electrons on their own, so a mediator is used
for electron transfer such as methyl blue, thionine. These are called Redox
mediators. H. J. Mansoorian, A. H. Mahvi, “Bioelectricity generation using
two chamber microbial fuel cell treating wastewater from food processing”, May
energy is converted into electricity by microbial activity. Microbes release
electrons. Oxygen is supplied to the cathode by air source. Materials use in
the electrodes influence the energy produced.
type of MFC is used widely. It contains two chambers. Anode is placed in one
chamber whereas cathode in another and is separated by a proton exchange
membrane. The anode chamber is kept oxygen free for anaerobic breakdown process
to occur. Though it is widely used by it is still challenging because of its
impractical configuration. This set up can accommodate various electrode
shapes, i.e. plane, granular and brush as it has a dedicated chambers for the
anode and cathode. It can also use other catholyte besides air, which is any
source of oxygen. According to a recent research document, use of algae
(seaweed) enhances the oxygen production due to photosynthetic process in the
plant which can be facilitated by this type of MFC configuration. A. González Del
Campo, P. Cañizares, M. A. Rodrigo, Nov. 2013
Figure 2.4: A Double-Chamber MFC
Single-chamber MFC Design:
one-compartment MFC eliminates the need for the cathode chamber by exposing the
cathode directly to the air. We are dealing with sand based MFC which has one
Chamber. Anode is dug inside the soil and cathode is at the top in exposed air
as shown in Figure 3.
The main applications of
is most recent and fantastic technology that uses wide variety of substrates,
materials with bacteria to achieve to produce bio energy despite the fact that
power level in these systems is relatively low. The
main objective of MFCs is to achieve a suitable current and power for the
application in small electrical devices. It
is specially used for sustainable long-term power applications. Rahimnejad and
et al. turn on ten LED lamps and one digital clock with fabricated stacked MFC
as power source and both devices were successfully operated for the duration of
2 days. M. Rahimnejad, A. Ghoreyshi, G. Najafpour,
type of waste water like sanitary waste, food processing waste water etc. can
contain energy in the form of biodegradable organic matter. MFC can capture
energy as electricity or hydrogen gas. MFCs using specific microbes are
excellent techniques to remove sulfides from wastewater. Up to 90% of the COD
can be removed in some cases.
fossil fuels are depleting soon we are looking for more sustainable methods and
one of them is microbial fuel cell technology for long term energy generation.
Microbial fuel cell concept is possible due to exocellular electron transfer.
Microbes are involved in this activity. Main step i.e. electron transfer, is
done by microbes. All the study of these microbes is done in a microbiology
lab. Without microbes this process is incomplete. It does not produce harmful
by products so it is more sustainable.
components are used in a basic soil based MFC:
assembly ( can be any bucket or container)
Anode: It is where
oxidation occurs and has positive polarity in cell.
Cathode: it is
where reduction occurs, and it is negatively charged. (The anode and cathode is
made from graphite fibre that is used for conduction as a medium)
board at which the wires are connected to complete the circuit.
Capacitor: it is
used to store the charge for the continuous generation of energy.
LED: light to show
the generation of current.
and Jumper wires ( to connect circuit with millimeter).
to measure current.
soil (sifted) atleast 4 cups or 400 grams. Soil from any area will work, from
backyard or open space. Make sure the soil hasn’t been treated with pesticides.
for handling soil includes: Measuring cups, container, distilled water, tape
the required amount of soil in cups and first make sure it has no big lumps,
rocks and twigs. Free the soil from these extra things.
distilled water if the soil is too dry, mix until a dough like structure is
start the assembly by taking the anode wire and putting its naked end free of
plastic into the graphite fiber.
wire should not come out of the disk and stay inside.
the same process with the cathode.
the soil sample and fill the vessel or container up to 1cm mark and place the
anode on top of that mud.
press the anode on the mud so to eliminate maximum air bubbles under the anode.
( removing the air bubbles is important, as the trapped oxygen can prevent the
formation of an anaerobic bacteria bio film and reduce the power output of your
more soil and fill up to 5cm more and once again pat the mud to remove excess
9. There should be no mud above the cathode.
the mud rest for a few minutes and drain the extra water before closing.
Figure 3.4: Addition of cathode
off excess mud from the edges and firmly place the lid taking the anode and
cathode wires out from the lid holes.
the hacker board on top of the lid and attach the anode to the (-) port and
Cathode to the (+) port.
the capacitor’s prongs into the ports 1 and 2. Capacitor is used to store the
charge that is produced over time.
the LED into ports 5 and 6. With the longer prong in port 5 and shorter in 6.
circuit is now complete, it should look like:
Figure 3.5: External
the MFC is set up, place it in normal room temperature (about 19-25° Celsius or
66-77° Fahrenheit F). The MFC should remain in the same location because
moving it could disrupt the growth of bacteria. Also temperature should remain
same or that could also affect the bacterial growth which in turn can affect
the power output.
the soil based MFC both anaerobic and aerobic processes take place. The anode
is placed in damp soil where the bacteria multiply and create a bio film on it
by providing electrons due to break down of organic or inorganic substrates
from the soil. The bio film has enzymatic action, it facilitates the transfer
the other side cathode is placed at top, leaving its one side exposed to air
travel from anode and react with oxygen at the cathode with protons from the
anode and create water. The more electricity bacteria is present in a nutrient
rich soil, the more current is generated.
Figure 3.6: Soil
bacteria set to work oxidizing and reducing the organic matter to generate life
sustaining ATP that fuels their energy. Protons, electrons and carbon Dioxide
are produced as by products with the anode serving as electron acceptor.
newly generated electrons pass from a node to cathode using the wire as bridge.
Finally oxygen present at the cathode combined the hydrogen and electrons to
form water, completing the circuit. And the led will harness the electrical
per this basic design, the LED blinks after 7 days, if the conditions are
perfect then the current can be produced early.
RESULT AND DISCUSSIONS
use mud from lake and set it up for the MFC. And it generated electricity which
illuminated the led light. This shows that we can use bacteria present in soil
for the production of electricity.
The design and optimization of
bio-electrodes and bio fuel cells is not trivial. This technology bridges
variety of research areas such as biotechnology, energy harvesting and
generation, environmental science, micro and nano structured materials.
Therefore, innovative and untraditional approaches need to be considered and
Though this technology is quite
promising as a source of renewable energy, it will be some time before
large-scale, highly efficient MFCs enter the commercial scene. The different
research groups working around the world will definitely overcome the
shortcomings being faced today, enthused and motivated by the immediate need
for alternate energy.
CONCLUSION AND RECOMMENDATIONS
more the material offered a better environment for production of electrons the
more easily and better is production of electricity.
is a good amount of electricity that can be produced in the MFC’s but this can
only be used in the places which lack proper sanitation and electricity because
the process of generating electricity in theses fuel cells also purifies the
water. In this way MFC’s may be may be helpful, but I cannot see them becoming
leading sources of power generation in near future.
cannot run a sensor or transmitter continuously with the generated power of the
cell. That is the main problem of the microbial fuel cell. Other limitation is
that we can only operate MFC at low temperature because microbial reactions are
slow at low temperatures. It is already acknowledged that one of the most important
factors that limit MFC power output is the reduction reaction that takes place
in the cathode. Furthermore, the high over potentials, high ohmic resistances,
and low kinetics observed in currently used cathodes have caused many problems
during the establishment of the oxygen reduction reaction
can made exceptions by increasing the surface of the electrode and also the
other solution is to use a suitable power management program. Data can only be
transferred when energy stored in ultra-capacitor for later use.
ENERGY AND THE CHALLENGE OF GLOBAL CLIMATE CHANGE:
is no ‘Magic Bullet’ for meeting our current and future energy needs. There is
no question that the release of stored carbon in fossil fuel is increasing the
concentration of carbon dioxide in atmosphere, with increase from 316 ppmv in
1959 to 337 ppmv in 2004.
the effects of climate change is a top priority of the Energy Department. As
global temperatures raise, wildfires, drought, and high electricity demand
put stress on the nation’s energy infrastructure. And severe weather the leading
cause of power outages and fuel supply disruption in the United States is
projected to worsen, with eight of the 10 most destructive hurricanes of all
time having happened in the last 10 years. To fight climate change, the Energy
Department supports research and innovation that makes fossil
energy technologies cleaner and less harmful to the
people and the environment. We’re taking responsible steps to cut carbon
pollution, develop domestic renewable
energy production and win the global race for clean
energy innovation. We’re also working to dramatically increase the efficiency
of appliances, homes, businesses and vehicles.