BIOHYDROGEN compare hydrogen energy to fossil energy sources




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            Hydrogen is the
simplest and most abundant element in the nature, along with being the lightest
chemical. Colorless, odorless, non-poisonous and 14.4 times lighter than air.  Among all fuels, hydrogen is the fuel with the
most energy per unit mass. (Upper heat value 140.9 MJ / kg, lower heat value
120.7 MJ / kg) 1 kg of hydrogen, 2.1 kg of natural gas or 2.8 kg of petroleum.
It is an average 1.33 times more efficient fuel than petroleum fuels. When we
compare hydrogen energy to fossil energy sources the amount of pollutants and
greenhouse gases produced are quite low. Today, most of the hydrogen is obtained
from natural gas, and unfortunately natural gas is also a fossil fuel. Today,
about 80% of the world’s energy needs are met by fossil fuels. Fossil fuel use;
air pollution, acid rain, global warming, climate change, ozone layer
perforation. The investigations prove that hydrogen energy will provide a more
active energy to negate the negative effects of fossil fuel use. Hydrogen
energy, defined as the energy of the new century, is a clean and efficient
energy system that does not contain any polluting gases and harmful chemicals
(such as carbon monoxide or carbon dioxide). However, in order to be used as
energy, it has to be separated from the compounds in the nature. Hydrogen is
the most environmental friendly hydrogen production with the separation of
water using the energy obtained from renewable sources such as wind and sun.
Hydrogen production in the world is basically as;

 -48% from natural gas,

 -30% from petroleum,

 -18% coal,

 It is produced from water
with -4% electrolysis.




            Biohydrogen is a
hydrogen gas (H2) which is produced biologically. This technology
draws interest of scientists
because H2 is a clean fuel, and H2 can be produced by
different kinds of biomass. Biohydrogen is the hydrogen which is produced
biochemically by the help of some microorganisms that
grow without oxygen in dark and/or light conditions from organic carbon sources
such as cellulose, hemicellulose, sugar or volatile fatty acids.




               Fermentation is the chemical disintegration of a substance through bacteria, fungi, and other microorganisms, usually by heat and foaming. Fermentation is an important biochemical process that provides ATP production by glycolysis under anaerobic conditions, that is, where oxidative phosphorylation is not possible. The branch of biochemistry interested in fermentation is zymology.In fermentation, glucose provides energy production by losing hydrogen individually. As there is no oxygen, the simple organic compounds resulting from this fragmentation are the final electron acceptor and hydrogen acceptor that the cell can use.Even if the last step of fermentation (conversion to pyruvate fermentation products) does not produce energy, this process is important for an anaerobic cell because nicotinamide, which is consumed during the conversion of glucose to pyruvate, allows the renewal of adenine dinucleotide (NAD +); This is necessary for the continuation of glycolysis. For example, in alcohol fermentation, the acetaldehyde formed in the vat is converted to ethanol by NADH + H +, which is expelled from the cell.In glycoses fermentation, the most commonly produced simple compound is pyruvate or one or more compounds derived therefrom: ethanol, lactic acid, hydrogen, butyric acid and acetone. While the fermentation of sugars and amino acids can be seen in various organisms, some rare organisms may also ferment alkanoic acids, purines, pyrimidines and other compounds. Various fermentation types are named according to the products they produce.Although fermentation is used in biochemistry for energy-generating reactions in the absence of oxygen, it has a more general meaning in the food industry, including the breakdown reactions of microorganisms in the presence of oxygen (such as vinegar fermentation). This term is used more generally in biotechnology, and any production (including proteins) fermentation done in microorganisms grown in large tanks is called fermentation.




Glycolysis is the sole source of
adenosine triphosphate ATP under anaerobic conditions. Fermentation products
contain chemical energy because they are not completely oxidized. However, in
the absence of oxygen or other highly oxidized electron acceptors, they are no
longer able to metabolize, leaving a residue for the cell. Therefore, ATP
production by fermentation is less efficient than oxidative fermentation, in
which the pyruvate is fully oxidized to carbon dioxide. While two ATP molecules
per glucose are produced in fermentation, this figure is 38 ATP in aerobic
respiration. Although the energy output is low, fermentation provides an
advantage to many organisms as it allows for the lack of oxygen.


The most common ingredient used for fermentation is sugar. Some of
the products obtained from this fermentation are carbon dioxide, ethanol,
lactic acid, and hydrogen gas (H2).


Ethanol fermentation

The chemical equation below shows the alcoholic fermentation of
glucose, whose chemical formula is C6H12O6. One
glucose molecule is transformed into two ethanol molecules and two carbon
dioxide molecules:

C6H12O6 ? 2 C2H5OH
+ 2 CO2

C2H5OH is the chemical formula for ethanol.

Before fermentation takes place, one glucose molecule is broken
down into two pyruvate molecules. This is known as glycolysis.

Hydrogen gas production in fermentation

Hydrogen gas is produced in many types of fermentation (mixed acid
fermentation, butyric acid fermentation, caproate fermentation, butanol
fermentation, glyoxylate fermentation), as a way to regenerate NAD+ from NADH.
Electrons are transferred to ferredoxin, which in turn is oxidized by
hydrogenase, producing H2. Hydrogen gas is a substrate for
methanogens and sulfate reducers, which keep the concentration of hydrogen low
and favor the production of such an energy-rich compound, but hydrogen gas at a
fairly high concentration can nevertheless be formed, as in flatus.

As an example of mixed acid fermentation, bacteria such as
Clostridium Pasteurian ferment glucose producing butyrate, acetate, carbon
dioxide and hydrogen gas. The reaction leading to acetate is:

C6H12O6+ 4 H2O ? 2 CH3COO?
+ 2 HCO3? + 4 H+ + 4 H2

Glucose could theoretically be converted into just CO2
and H2, but the global reaction releases little energy.




Molasses is a viscous product resulting from refining sugarcane or
sugar beets into sugar. Molasses varies by amount of sugar, method of
extraction, and age of plant. Sugarcane molasses is agreeable in taste and
aroma, and is primarily used for sweetening and flavoring foods in the United
States, Canada, and elsewhere, while sugar beet molasses is foul-smelling and
unpalatable, so it is mainly used as an animal feed additive in Europe and
Russia, where it is chiefly produced. Molasses is a defining component of fine
commercial brown sugar. Some cations and amino nitrogen compounds inhibit sucrose uptake during
fabrication. After the sucrose is extruded, the remaining liquid is called molasses.

Sweet sorghum
syrup may be colloquially called “sorghum molasses” in the southern
United States. Similar products include treacle, honey, maple syrup, corn
syrup, and invert syrup. Most of these alternative syrups have milder flavors.


•          The carbon source for in situ
remediation of chlorinated hydrocarbons

•          Blended with magnesium chloride and
used for de-icing

•          A stock for ethanol fermentation to
produce an alternative fuel for motor vehicles

•          As a brightener in copper
electroforming solution when used in tandem with thiourea





Today, consumption of fossil fuels is increasing. Efforts to
destroy the ecosystem, to get rid of foreign dependence in the energy field of
the country and to increase energy diversity have increased the importance of
fuels like bioethanol. Production of bioethanol from sugar beet mulberry as
biomass will lead to the opening of a new market for beet crops, the spreading
of planting seasons, the cultivation of energy agriculture and the increase of
sugar beet cultivation areas. At the same time, bioethanol is also important in
terms of contributing to the diversity of agricultural production, contributing
positively to ecology, establishing a sustainable agricultural structure, and
supporting rural development. Bioethanol is generally obtained by fermentation
from plants containing sugar and starch. Molasses is used in the production of
bioethanol in sugar beet. Melastan bioethanol production; fermentation,
distillation. The alcohol obtained in ethanol production is 96% pure and can
not be used as fuel alcohol. Ethyl alcohol must be at least 99.5% pure in order
to be able to use it as fuel. For this reason, alcohol plants require
purification and dewatering units after the fermentation unit. Today, due to
the decrease of oil reserves and environmental problems, alternative energy
sources such as bioethanol should be emphasized.




               Biomass production by fermentation occurs in two ways, photo fermentation and dark fermentation.

Photo fermentation

The photosynthetic microorganism produces H2 by catalyzing organic acids with nitrogenase in the presence of solar energy. Hydrogen Production with Photo Fermentation The reaction is as follows;C6H12O6 + 6H2O + light energy ? 12H2 + 6CO2

Hydrogen Production with Photosynthetic
Bacteria for Industrial Production;

-The formation of high theoretical conversion efficiency,The absence of oxygen evolution, which causes the problem of loss of activity in distinct biological systems,- The availability of light in the broad spectrum,- It has advantages such as organic substrates which can derive from the wastewater, and the ability to consume them, to have wastewater treatment potency.

Dark Fermentation

During the production of hydrogen by dark fermentation, anaerobic bacteria produce hydrogen in dark conditions using organic substrates. Because the anaerobic bacteria used do not need the light. Hydrogen Production with Dark Fermentation The reaction is as follows;C6H12O6 + H2O – & 4H2 + 2CO2 + 2CH3COOH


Production of Hydrogen by Dark
Fermentation for Industrial Production;

– No need for light energy,

– the availability of various carbonaceous wastes as

-Manufacture of organic acids as a product of the sea, it has
the advantages of not having oxygen restriction problem.

Factors Affecting Biohydrogen Production –
Substrate Factor:

Three different substrates (biomass) can be used:
sugar-containing biomass, starchy biomass, lignocellulosic biomass. These
biomasses may be various agricultural wastes or industrial wastes.

– Bio Degenerative Bacteria Factor: According to the
fermentation type, photosynthetic and fermentative bacteria are used. In the
selection of the bacteria, conversion efficiency, formed by-products,
environmental conditions (temperature, pH) are important.

– Reactor Type Factor: The hydrogen yield can be increased by
selecting the appropriate parameters such as the organic loading rate in full
stirred continuous reactors. Alternatively, the arrested cell reactor type and
the biofilm reactor type may be used. As the volumetric hydrogen production
rate increases, the reactor size shrinks.

– Nitrogen and Phosphorus Factor: Protein, Nucleic acid and
the structure of enzymes is necessary because of the presence of nitrogen.
Phosphate is required for reaction with both its nutrient value and its
buffering capacity.

– Metal Ion Factor: The cell ATP increases enzyme activity in
NAD synthesis. When used at extreme concentrations; preventing the formation of
the desired enzyme, can cause high osmotic pressure.

 – Temperature Factor:
The temperature increase in the appropriate range increases the ability of the
bacterium to produce hydrogen. But at very high temperatures this ability is
reduced due to degradation of the enzymes. The cell can die. The optimum
temperature for mesophilic interval is 37 C, for thermophilic range is 55 C.

– Acid Blocker Effect and pH Exchange Factor: Due to high
conversion, the environment can be acidified by means of by-products. Non-polar
acids change the intracellular pH by populating the cell wall at low pH. This
creates an inhibition effect. The optimum pH for hydrogen production is in the
range of 5-7.

Partial Pressure Factor: The hydrogen pressure in the reactor decreases the
hydrogen production. Hydrogenase converts the hydrogen in the liquid to
ferrodoxine. vacuum application, inert gas spraying, strong mixing, nitrogen
and hydrogen permeable membranes can be applied.

?eker pancar?ndan elde edilen ba?l?ca ürün ?ekerdir ve
?eker oldukça fazla mikroorganizma ile kolayl?kla fermente olabilme özelli?ine
sahiptir. Bir ton ?eker pancar?ndan yakla??k olarak %50 sakkaroz içeren 20 kg
melas elde edilmektedir. Kökten sakkaroz ve melas elde edildikten sonra geriye
posa kalmaktad?r. ?eker pancar?n?n ekstraksiyon i?lemi sonras?nda çözünemeyen, ?eker
pancar? kökündeki %22 ile %28 oran?nda de?i?en kuru madde posay? temsil
etmektedir ve bu posa fermente olabilme özelli?ine sahiptir. ?ekerin etanole
dönü?üm sürecinde mayalar ve baz? bakteriler ?ekerlerin anaerobik çevirimi ile
fermantasyon sa?lamas?nda rol oynamaktad?rlar. Dünya etanol yak?t üretiminin
neredeyse yar?s? ?eker bitkilerinden üretilmektedir (ço?unlukla ?eker kam???
melas?) di?er kalan yar?s? ise tah?llardan üretilmektedir. ?eker bitkileri
dünyada çok geni? alanlarda yeti?tirilebilmektedir. Bu nedenle, tah?llara göre
baz? avantajlar? bulunmaktad?r. ?eker pancar?n?n tah?llara ve di?er selüloz
içeren bitkilere oranla bir ba?ka avantaj? daha bulunmaktad?r. Bu da do?rudan
fermente edilmeleri nedeniyle daha az sürece ihtiyaç duymalar?d?r. Enerjiye dönü?türülebilme
potansiyeline sahip olan bitkiler olarak ?eker kam???, ?eker pancar? ve tatl?
sorgum s?v? yak?t yani etanol, ?s? ve elektri?e çevrilebilmektedirler.

Dünyadaki Durum

”2014 y?l?nda AB ülkelerinde üretilen 6.6 milyar litre
etanol m?s?r (%42), bu?day (%33), ?eker pancar? (%18), ve di?er tah?llardan
(%7) elde edilmi?tir. Toplam 10.5 milyon ton tah?l ve 2.21 milyon ton kota d???
?eker pancar? (beyaz ?eker e?de?eri) etanol üretimi için kullan?lm??t?r. Bu
de?erler 2014 y?l? için Avrupa tah?l üretiminin %2’si ile ?eker pancar?
üretiminin %8’ine kar??l?k gelmektedir. Dünyada 2014 y?l?nda üretilen 90.5
milyon litre yenilenebilir etanol üretiminde Avrupa çok küçük bir paya
sahiptir. Üretilen etanolün ço?u yenilenebilir ta??t yak?t? olarak iç tüketime
yöneliktir. ABD (%60) ve Brezilya (%30) en fazla etanol üreten ülkelerdir ve
Avrupa Birli?indeki üretim ise (%7) daha dü?üktür.”

?ekerin etanole dönü?ümü sadece fermantasyonu içeren
basit bir i?lemdir, fakat m?s?r, bu?day vb. tah?llardan s?v? yak?t elde
edilmesi için ni?astan?n ?ekere dönü?ümü i?leminde enzimlere de ihtiyaç vard?r.
Ancak tah?llar ile kar??la?t?r?ld???nda bioetanol hammaddesi olarak ?eker
pancar? kullan?m?nda ?eker pancar? köklerinin depolanmas? önemli bir engel
olarak görülmektedir. Birim alan dikkat etti?imizde ise ?eker pancar? etanol
için en verimli kaynaklardan birisidir. ”?eker pancar?ndan (taze a??rl?k
olarak) 2.44 GJ/t enerji elde edilebilmekte ve bu de?er etanole çevrildi?inde
115 l/t etanol üretildi?i varsay?lmaktad?r. Ortalama verimi dikkate al?nd???nda (46 t/ha pancar, 4.9 t/ha
m?s?r, 2.8 t/ha bu?day) pancardan 5.060 l/ha, bu?daydan 952 l/ha ve m?s?rdan
1.960 l/ha alkol elde edilmi?tir. ABD ve Avrupa’da, k??l?k pancar?n
yeti?tirildi?i Akdeniz, yar? tropikal ve kurak tropikal iklimlerde sulama
yap?l?yorsa verim potansiyeli çok yüksektir. K??l?k pancar?n yeti?me süresi
210-300 gündür, geç yazda ekilip takibeden geç ilkbahar veya yaz aylar?nda
hasat edilmektedir. 100 t/ha pancardan 115 l/t (taze a??rl?k) etanol
üretilmektedir, etanol verimi 11.500 l/ha ile ABD’de m?s?r veriminden elde
edilenden 3 kat daha yüksek olmu?tur (9.4 t/ha m?s?r veriminden 3751 l/ha). ”

Hem yazl?k ve hem de k??l?k ?eker pancar? üretilen
iklimler biyoyak?t üretimi için en çok tercih edilen yerlerdir çünkü bu iklim
tiplerinin görüldü?ü yerlerde y?l?n büyük bir k?sm?nda pancarlar günlük hasat
edilebilmektedir. Biyokütle verim potansiyeli, al?nan güne? enerjisine ba?l?
olup bu ko?ullar vejetayon süresi uzun olan k??l?k pancar için avantajl?
olmaktad?r. Biyoyak?t
için biyokütle verimi en önemli parametre olarak kabul edildi?inde ?eker
pancar?n?n melezlenmesi ile daha yüksek biyokütle elde edilebilecektir.

?e?er Pancar? Üretiminin Artmas? Nas?l Desteklenmelidir?

Ülkemizde motorlu araç say?s?n?n her geçen gün artmaktad?r,
akaryak?t masraf?n?n çok yüksek olmas? alternatif enerji kaynaklar?na üretimine
yol açm??t?r. Ayn? zamanda araçlar?n da motorlar?n?n bu tür yak?tlar?
kullanabilecek ?ekilde yap?lmas? gerekmektedir. ?eker fabrikalar? bünyelerinde
bulunan alkol üretim tesislerin yaln?zca susuzla?t?rma birimi eklenerek
biyoetanol üretimi yap?labilecek duruma geleceklerdir. ?eker fabrikalar?n?n
üretim kapasitelerine uygun olarak i?lenecek ?eker pancar? üretimi
art?r?lmal?d?r. Ayr?ca ülkemizde yeti?tirilmekte olan yazl?k pancara ek olarak
biyoetanol üretimi için k??l?k pancar üretimi de dü?ünülmelidir. Ancak pancar
ekim alanlar?n?n artt?r?lmal?d?r. Biyoetanol içerikli benzin kullan?ld???nda
tar?m sektörü desteklenecek, araçlar?n performans? yükselecek, hem de daha ucuz
yak?t ve daha temiz ve sa?l?kl? bir çevre söz konusu olacakt?r.



K?saca hidrojen enerjisi di?er fosil enerji kaynaklar?yla
kar??la?t?r?ld???nda enerji verimlili?i, kaynak çe?itlili?i ve çevreye zararl? etkisi
bulunmamas? aç?s?ndan üstün bir konumdad?r. Bu nedenle üretim maliyetinin
dü?ürülerek hidrojen enerjisinin kullan?m?n?n artt?r?lmas? ve
yayg?nla?t?r?lmas?n?n dünyam?z?n gelece?i aç?s?ndan birincil derecede önemli
oldu?u kabullenmelidir. Bilim adamlar?na göre küresel ?s?nman?n, çevre
kirlili?inin, görüntü kirlili?inin, asit ya?murlar?n?n, ozon tabakas?n?n
delinmesinin, iklim de?i?ikli?i gibi birçok önemli sorunun tek ve kal?c? çözümü
hidrojen enerji sisteminin kullan?lmas?d?r. Biyolojik yolla hidrojen üretimi
hidrojen gaz? üretimi için iyi bir alternatiftir. Biyolojik yolla hidrojen
üretim teknolojilerinden mevcut ko?ullara göre maliyet ve verimlilik aç?s?ndan
en uygun olan? seçilerek üretimde kullan?lmal?d?r. Çünkü kullan?lan
biyokütleye, enzim türüne, mikroorganizma türüne, ortam ko?ullar?na göre
seçilecek yöntem farkl?l?k gösterecektir. Bu nedenle yöntemler aras?nda
kar??la?t?rma yaparak herhangi bir yöntemin di?erlerine göre daha iyi oldu?unun
söylenmesinin yanl?? oldu?u aç?kça ortadad?r. Ayr?ca bu yaz?da da üzerinde
durulan ve biyohidrojen üretiminde çok önemli bir pay? olan at?k materyal
seçimi do?rudan verimi etkileyecek bir faktördür. Bu nedenle bol miktarda ve
kolay bulunabilen, ucuz, i?lemler s?ras?nda kolayca parçalanabilen ve kirlili?i
ortadan kald?r?rken yeni bir kirlilik olu?turmayacak at?k materyal seçimine özen
gösterilmelidir. Böylece farkl? at?k materyallerden biyohidrojen üretimi ile
hem at?k materyalin kullan?m? hem de temiz enerji kayna??n?n üretimi sa?lanm??