Download ENERGY SELF-SUSTAINING AND ENVIRONMENTAL FOOTPRINT

ENERGY SELF-SUSTAINING
AND ENVIRONMENTAL
FOOTPRINT REDUCTION
ON WASTEWATER
TREATMENT PLANTS VIA
FUEL CELLS
LAYMAN’S REPORT 2012
LIFE07 / ENV / E / 000847
OUTLINE
CONTEXT AND BACKGROUND
2
THE BIOCELL PROJECT
6
Introduction
7
Fuel cell technology: the clean and efficient path
8
Methodology: pilot plants description
12
RESULTS
14
PEMFC results
15
SOFC results
18
Environmental assessment
20
Fuel cell application field
21
DISSEMINATION
24
CONCLUSIONS
28
CONTEXT AND
BACKGROUND
LAYMAN’S REPORT
BIOCELL
CONTEXT AND BACKGROUND
Every time we turn on the tap and wash our hands, the water passes down
the sink, towards the sewage network, where a series of pipes and tubes interconnected to every street of our villages, towns and cities, are responsible
for carrying it to the wastewater treatment plant (WWTP). Then it runs through
a series of complex systems where modern technologies purify it.
Energy consumption in Wastewater treatment plants accounts for around
25 – 35% of the total operational expenditures of sewage treatment.
WASTEWATER TREATMENT COSTS
REAGENTS 5%
OTHERS 5%
MAINTENANCE 13%
MANPOWER 30%
SLUDGE AND
WASTE 17%
ENERGY 30%
MURCIA ESTE WWTP
3
BIOCELL
LAYMAN’S REPORT
CONTEXT AND BACKGROUND
Taking into account the expected increase on the worldwide energy demand (up to 45% in 2030, International Energy Agency), the energy cost and
its corresponding environmental impact will surely rise, affecting the water
sector since it is highly energy-intensive. Therefore, energy in WWTP must be
considered not only in terms of consumption reduction, but also in terms of
production and use of “green” energy. In addition, the emissions of greenhouse gases from water utilities have to be reduced and synergies for the
reduction of these emissions have to be identified.
Anaerobic digestion is widely used in WWTP to treat sludge and organic wastes
because it provides volume and mass reduction of the input material and
is also a renewable source of energy as the process produces a methane
rich biogas suitable for energy generation. For long time, chemical energy
contained in the biogas was transformed into electricity in Internal Combustion Engines (ICE) and more recently in micro-turbines.
RAW
SEWAGE
BIOGAS
CLEANING
(REMOVAL OF
WATER, H2S,
SILOXANES, ...)
CLEAN
SEWAGE
BIOGAS
(CH4+CO2)
4
Nowadays, new promising technologies have been developed which
offer both a higher efficiency and a further reduced environmental impact:
fuel cells.
CLEAN SEWAGE
BIOGAS
(CH4+CO2)
REFORMING
LOW
TEMPERATURE
FUEL CELLS
HIGH
TEMPERATURE
FUEL CELLS
CLASSIC
COGENERATION
COMBINED
HEAT AND POWER
5
THE BIOCELL
PROJECT
LAYMAN’S REPORT
BIOCELL
THE BIOCELL PROJECT
INTRODUCTION
The BIOCELL project, with a 2.4 M€ budget funded by the LIFE+ Programme
of the European Commission (LIFE07 ENV/E/000847), has the main goal of
demonstrating the technical feasibility of energy production from biogas
both with low - and high - temperature fuel cells.
Secondary objectives include:
- Technical assessment: guidelines on selection, implementation, operation and optimization of energy production from biogas, via fuel cells
adapted to WWTP
- Feasibility and impact assessment: energy self-sustainability, economic
feasibility and reduction of environmental impact of WWTP using biogas
energy recovery via fuel cells.
- Application field: biogas as a fuel, requirements and limits.
CETaqua is the coordinating beneficiary of the project and the ultimate
responsible of its success. Apart from CETaqua, three other partners are
strongly contributing to the project: EMUASA, CIRSEE and Degrémont. In
addition, the project stakeholders are actively involved, as well as several
biogas treatment suppliers and fuel cell manufacturers.
PROJECT STAKEHOLDERS
7
BIOCELL
LAYMAN’S REPORT
THE BIOCELL PROJECT
FUEL CELL TECHNOLOGY: THE CLEAN AND EFFICIENT PATH
A fuel cell is an electrochemical device that directly turns the chemical energy
of a fuel into electricity. This conversion avoids the Carnot efficiency limitation
present in combustion engines, what implies a higher efficiency by design.
FUEL CELL WORKING PRINCIPLE
ELECTRIC CURRENT
FUEL IN
AIR IN
e-
e-
H+
e-
eO2
H2
H+
H2 O
EXCESS
FUEL
ANODE
CATHODE
ELECTROLYTE
UNUSED
GASES OUT
The basic working principle for all the fuel cells consists in an oxidation/reduction
reaction in which fuel (e.g. biogas) is oxidized, and oxygen is reduced, thus
exchanging electrons and producing an electrochemical induced current.
8
Eventually, biogas-powered fuel cells combine a high-efficient technology
for electrical generation with the use of a renewable fuel, hence being
one of the most environmentally friendly technologies that can contribute to
energy self-sufficiency in WWTP. Nevertheless, biogas needs to go through a
thorough and extensive process of cleaning upstream the fuel cell in order
to remove its pollutants.
COUPLING RAW BIOGAS TO FUEL CELLS
Biogas contains many compounds that are harmful to fuel cell materials, especially for catalysts. Their tolerance to these compounds varies depending
on each pollutant, and type of fuel cell:
COMPOUND
SOFC*
MCFC*
PAFC*
PEMFC*
H2 S
<0,1 ppm
<0,1 ppm
<20 ppm
0,1 ppm
0,5 - 1
0,5 - 1
0,5 - 1
0,2
mgSi/m3
mgSi/m3
mgSi/m3
mgSi/m3
HALOGENS
<1 ppm
<0,1 ppm
4 ppm
not known
CO
acts as fuel
acts as fuel
1%
10 ppm
SILOXANES
(HCI)
HIGH TEMPERATURE
LOW TEMPERATURE
*SOFC: Solid Oxide Fuel Cell
*PAFC: Phosphoric Acid Fuel Cell
*MCFC: Molten Carbonate Fuel Cell
*PEMFC: Proton Exchange Membrane Fuel Cell
BIOGAS CLEANING UPSTREAM THE FUEL CELL
9
BIOCELL
LAYMAN’S REPORT
THE BIOCELL PROJECT
In order to comply with the stringent inlet requirements of both low - and
high - temperature fuel cells, a previous biogas cleaning step is necessary.
Different technologies are available for this purpose:
ACTIVATED
CARBON
CHEMICAL
SCRUBBERS
BIOSCRUBBER
MAIN
REMOVAL
(H2S)
GAS
CLEANING
TECHNOLOGIES
IRON
SPONGE
BIO-TRICKLING
FILTER
BIOGAS CLEANING TECHNOLOGIES
10
POLISHING
(H2S,
SILOXANES,
VOCs)
After the cleaning of the biogas, further processing of the biogas is needed,
depending on the operating temperature and type of fuel cell:
RAW
BIOGAS
BIOGAS
TREATMENT
CLEAN
BIOGAS
REFORMING
CO
REMOVAL
CO CATALYTIC
OXIDATION
DRY REFORMING
STEAM REFORMING
WATER GAS SHIFT
COPROX
30-50% H2
5-20% CO
50-65% H2
<1% CO
50-65% H2
<10 ppm CO
SOFC
MCFC
PAFC
PEMFC
High temperature fuel cells (SOFC and MCFC) internally process the biogas.
On the contrary, low temperature fuel cells (especially PEMFC) need an
external fuel processing, plus further CO removal.
11
BIOCELL
LAYMAN’S REPORT
THE BIOCELL PROJECT
METHODOLOGY: THE TWO PILOT PLANTS
Two pilot plants in Spain have been
built in order to achieve the objectives
of the project.
The plant in Murcia contains a Proton Exchange Membrane Fuel Cell (PEMFC),
which operates at low-temperature
(around 65 ºC), and has been designed to produce 3 kW of electric power,
using 10 m3/h of biogas.
PEMFC PILOT PLANT IN MURCIA ESTE
WWTP INSTALLATION SITE
The biogas cleaning is achieved by
using a caustic scrubber, followed by a drying process (removal of water)
and, eventually, adsorption on activated carbon and silica gel (for extra
drying of the gas) to achieve the stringent fuel requirements of the fuel cell.
Since hydrogen is the only fuel that is
accepted by PEMFC, a biogas
“reforming” process, from methane to
hydrogen, is necessary. The BIOCELL
project has developed a specific and
innovative biogas dry reforming
process, producing a high quality reformed gas suitable for PEMFC.
CLOSE VIEW OF PEMFC PILOT PLANT
RAW
BIOGAS
10 m /h
3
CLEANING
NaOH SCRUBBER
+ DRYING + AC
+ SILICA
CLEAN
BIOGAS
REFORMING
DRY REFORMING +
CO PURIFICATION
REFORMED
GAS
FUEL CELL
PEMFC
ELECTRICITY
3kWe
12
The plant in Mataró contains
a Solid Oxide Fuel Cell (SOFC),
which operates at high temperature; around 800 ºC. It has a
design power of 2.8 kW, and the
plant treats a biogas flow rate
of 10 m3/h.
In this case, a biotrickling filter is
used as the main biogas desulTHE PILOT PLANT IN MATARÓ
phurization technology. Biogas is
further purified by the polishing system via adsorption on iron oxides, biogas
drying, and further adsorption of other contaminants on activated carbon.
Clean biogas directly fuels a completely heat-integrated SOFC unit
producing both electricity and
heat.
BIOGAS CLEANING SYSTEM
OF SOFC PILOT PLANT
THERMAL ENERGY
0,9 kWt
RAW
BIOGAS
10 m /h
3
CLEANING
BIOTRICKLING FILTRE
+ IRON SPONGE
+ DRYING + AC
CLEAN
BIOGAS
FUEL CELL
SOFC
ELECTRICITY
2,8 kWe
13
RESULTS
LAYMAN’S REPORT
BIOCELL
RESULTS
Technical, economical and environmental indicators have been gathered
during the whole project, and especially during the operation of both pilot
plants, regarding design, start-up and operation of biogas treatment and
fuel cells adapted to WWTP.
PEMFC PLANT RESULTS
The results on operation and performance can be divided in two separate
chapters: the biogas cleaning system (or treatment line), and the fuel cell
(including the reforming of methane into hydrogen).
Treatment line
After some trials to determine the best operating parameters for the treatment
line, results from long-term operation, over a period of 6 months, have been
gathered:
TREATMENT UNIT
PARAMETER
AVERAGE VALUE
CHEMICAL WASHING
(NaOH SCRUBBER)
H2S in (ppm)
4000
H2S out (ppm)
300
removal efficiency (%)
93
POLISHING
(DRYING + ACTIVED
CARBON)
EXTRA DRYING
(SILICA)
H2S out (ppm)
<0,1
siloxanes in (mgSi/m3)
3
siloxanes out (mgSi/m3)
<0,1
removal efficiency (%)
>99
H2S out (RH%)
<2
removal efficiency (%)
92
Even though the content in sulphur is very high, its removal is effectively carried out by a caustic scrubber, a very mature and commercially deployed
technology that uses chemicals (soda) to remove the sulphur. The rest of
contaminants are removed by adsorption on activated carbon with efficiencies higher than 99%.
With this combination of technologies, it is possible to achieve the fuel
cell inlet requirements
15
BIOCELL
LAYMAN’S REPORT
RESULTS
Operational expenditures (OPEX) are between 6 – 7 c€/m3 of treated biogas,
and are fairly split between caustic scrubbing and the polishing system:
27.000 kWhe 800 KgNaOH
year
year
RAW
BIOGAS
10 m3/h
70 m3 H2O 80 Kg AC
year
year
CLEAN
BIOGAS
BIOGAS TREATMENT
9,15 m3/h
70 m 3 bleed
year
OPEX
Caustic scrubbing
3-3,5
c€/m3
Polishing
3-3,5
c€/m3
6-7
c€/m3
TOTAL
CAUSTIC SCRUBBING AND POLISHING OF PEMFC PILOT PLANT
16
The reforming process for the fuel cell has accounted up to a total operation
of 385h, demonstrating that it is possible to produce a suitable gas to be
used as a fuel for PEM fuel cells:
1 Nm3/h
WGS
REF
PEMFC
COPROX
PEMFC
2 X PEMFC
3kW, 2,4 Nm3/h
4,58 Nm3/h
CH4/CO2 1:1
GAS
COMPOSITON
BURNER
FUEL REFOMRING PROCESS
These results indicate that a good reforming performance has been achieved, reaching hydrogen contents up to 44%, and CO concentrations lower
than 4 ppm.
In addition, a case study for a PEMFC unit of 3 kW has been built in order to
forecast the technical performance of such systems, leading to the following
outputs.
PARAMETER
UNIT
AVERAGE VALUE
INSTALLED POWER
kW
3
PRODUCED POWER
kW
1
ELECTRICAL EFFICIENCY
%
10,4
EXHAUST GAS TEMPERATURE
ºC
120
THERMAL POWER
kW
0,2
THERMAL EFFICIENCY
%
4,3
These simulation results indicate that more basic research is still needed
to enhance the technical performance and feasibility of these complex
and innovative systems.
17
BIOCELL
LAYMAN’S REPORT
RESULTS
SOFC PLANT RESULTS
The results are as well presented considering that the plant has two functional areas: the treatment line (contaminant removal) and the fuel cell (power
generation).
Treatment line
After the execution of many short experiments to determine the best operating conditions, long-term operation over a period of 12 months of the biogas
treatment, offered the next average results:
TREATMENT UNIT
BIOTRICKLING FILTER
POLISHING
(IRON OXIDES +
DRYING + ACTIVED
CARBON)
PARAMETER
AVERAGE VALUE
H2S in (ppm)
3100
H2S out (ppm)
800
removal efficiency (%)
70
H2S out (ppm)
0
siloxanes in (mgSi/m )
5
3
siloxanes out (mgSi/m )
<0,1
removal efficiency (%)
100
3
The main sulphur removal is carried out by the living bacteria, inside the
biotrickling filter (around 70%). The remaining sulphur content is adsorbed
in the iron oxides with removal efficiencies higher than 99.9%. Other harmful
contaminants (such as silicon and halogenated compounds) are as well
completely removed by adsorption on activated carbon.
18
The operational expenditures account up to a total of 5-6 c€/m3 of treated
biogas, being the polishing step the responsible of 90% of these costs due
to ferric oxide and activated carbon consumption:
20.000 kWhe
year
RAW
BIOGAS
10 m3/h
1500
kWhe 90 KgNaOH 450 KgBiOnFe 300 Kg AC
year
year
year
year
CLEAN
BIOGAS
BIOGAS TREATMENT
(AVAILABILITY 79%)
11,1 m3/h
130 m3 bleed
year
Biotrackling filter
Polishing
TOTAL
0,5-0,6
c€/m3
4-5
c€/m3
5-6
c€/m3
Soda consumption is considerably lower than for a caustic scrubber (PEMFC
plant), since it is not needed for regular operation, but necessary to periodically clean up the biotrickling filter.
Considering all short and long-term operational results, it has been demonstrated that this treatment line is prepared to meet the stringent requirements
of the fuel cell.
19
BIOCELL
LAYMAN’S REPORT
RESULTS
Fuel cell
Experimentation of the SOFC was carried out for a total of 220 hours, giving
the next average results:
PARAMETER
UNIT
AVERAGE VALUE
INSTALLED POWER
kW
2,8
PRODUCED POWER
kW
1,3
ELECTRICAL EFFICIENCY
%
24,2
EXHAUST GAS TEMPERATURE
ºC
240
THERMAL POWER
kW
2,1
THERMAL EFFICIENCY
%
39,4
These experimental results indicate
that electrical and thermal efficiencies are high. In particular, the electrical efficiency of stack, which has
been of 48.5%, is comparable to large
power generation facilities (> 500 kW).
However, the achieved electrical
power only reached 45% of its design
power (which is 2.8 kW), because at
high fuel loads, operation was unstable due to insufficient heat evacuation
capacity.
SOFC UNIT INSTALLED IN
MATARÓ WWTP
20
ENVIRONMENTAL ASSESSMENT
The environmental impact of the two units was assessed, including the manufacturing and operation of both facilities. The Life Cycle Assessment is based
on inventory data, and has been carried out according to the following steps:
DEFINITON OF THE
OBJECTIVES & SCOPE
OF THE STUDY
At this stage each
impact is charcterized,
the study may be limited
at this stage if it meets
the initial objectives
The analysis can be
limited to the Inventory
if the objectives are met
Evaluation allows,
at the end of the
study, to score
every studied
hypothesis
INVENTORY
CLASSIFICATION
CHARACTERITZATION
NORMALITZATION
EVALUATION
Sensitivity analysis &
weighing of different
environmental imapcts
The environmental assessment has been carried out both for the construction
and the operation phases. The results for the construction phase show that
energy conversion systems (the fuel cells) are the main contributors to the
environmental impact, both in PEMFC and SOFC pilot plants, having a much
higher impact than their corresponding biogas cleaning and conditioning
steps.
ENVIRONMENTAL
OPERATION OF
CONSTRUCTION
CONSTRUCTION
As for the operation
IMPACT
THE WHOLE PILOT
OF TREATMENT
OF FUEL CELL
PLANT
LINE
phase, fuel cells show
a positive environmental impact because of
green electricity and
PEMFC PILOT PLANT
green thermal energy
ENVIRONMENTAL
SOFC PILOT PLANT
generation, comparable
BENEFITS
to mature and already
deployed technologies
such as Internal Combustion Engines (ICE). Results are influenced by the
location where they are calculated; hence the environmental impact will be
more positive in countries with a high-carbon electricity mix, such as Spain,
but smaller in low-carbon countries, such as France.
21
BIOCELL
LAYMAN’S REPORT
RESULTS
FUEL CELL APPLICATION FIELD IN WWTP
The application field of fuel cells adapted to WWTP was studied, and compared with other technologies. A technical
and economic study of different case
studies has been issued with the objective of giving recommendations for
the choice of different CHP (Combined
Heat and Power) technologies and
their required biogas treatment.
MATARÓ WWTP
The model used for this case study assessment is comprised of the information gathered by the two pilot plants, and other literature and manufacturer
information.
MATARÓ
SOFC PILIOT
MURCIA
PEMFC PILIOT
BIOGAS FLOW,
COMPOSTION
REVENUE
MODEL
OPERATION
COSTS
ENERGY COSTS
LITERATURE
INTERNAL
EXPERIENCE
22
PROCESSES
MATHEMATICAL
MODELS
DATA FROM
MANUFACTURERS
INPUTS
INTERNAL
DATABASE
OUTPUTS
BIOCELL
PILOT DATA
Different plant sizes, types of biogas and end-use technologies have been
considered, building up to a total of 24 case studies:
500.000 PE
(312,5 m3/h)
100.000 PE
(62,5 m3/h)
H2S = 2500 ppm
VOSiC = 10 mg/Nm3
FLARE
ICE
ICE + ORC
H2S = 250 ppm
VOSiC = 10 mg/Nm3
MICROTURBINE
MCFC
SOFC
PEMFC
In this assessment, it has been observed that MCFC are technically superior. In addition, these electrochemical devices have very clean emissions,
what is a potential advantage towards future stringent legislation standards.
However, when economic considerations come into play, microturbines
and especially internal combustion engines are the unique technologies
that offer investment payback. Fuel cell facilities can only be considered if
investment subsidies are provided.
In any case, results have also shown that most of these technologies can
cope with the heating demand of a WWTP, while satisfying up to 60-70%
of its electrical needs.
23
DISSEMINATION
LAYMAN’S REPORT
BIOCELL
DISSEMINATION
Communication and dissemination of results and other important information has been carried out from the very beginning of the project, including:
Website and video
A project website (http://www.life-biocell.eu) has been developed to
open the door to the internet. The web contains general information about
the project and its participants, receiving up to 760 visits per month.
A short 15 minutes documentary with a global overview of the entire BIOCELL
project is also available in this website.
Conferences and publications
Publications on general media and technical/scientific journals and conferences have been a very important part of the communication plan, including:
- 8 publications at general and scientific media (local and worldwide
newspapers and magazines)
25
BIOCELL
LAYMAN’S REPORT
DISSEMINATION
- 7 oral presentations and 9 posters at different technical conferences
(including International Water Association, European Fuel Cell and International Water Week events, amongst others)
- 6 oral presentations at workshops (including Water supply and sanitation Technology Platform, International Energy Agency, and others)
Technical visits
On-site visits of partners and manufacturers involved in the project, as well as
external audience, have also been organized, in order to enhance project
dissemination in a more technical point of view. A total of 20 visits, 13 at the
SOFC pilot plant and 7 at the PEMFC pilot plant, have been carried out.
VISIT OF THE TECHNICAL COMITEE
OF SUEZ ENVIRONNEMENT TO
THE PEMFC PILOT PLANT
VISIT OF THE AGBAR - UPC MASTER
(2011/12) IN WATER MANAGEMENT
TO THE SOFC PILOT PLANT
Workshop
A final workshop in Barcelona took
place in June 2012, with the participation of more than 50 people,
including participants and other
audience related to the world of
biogas exploitation (Administration,
stakeholders, providers, etc.).
WORKSHOP SESSION IN BARCELONA
26
AwardS
The BIOCELL project received the following awards, which acknowledge the
quality of the project results and the efforts made by all participants.
1. Honour Awardee at the Europe – West Asia Project Innovation Awards
2012 organized by the IWA for the category Applied Research
(May 15th of 2012, Brussels, Belgium)
2. Best poster presentation award of the conference ORBIT 2012
“Global assessment for organic resources and waste management”
(June 13th of 2012, Rennes, France)
3. Grand Honour Awardee at the World Project Innovation Awards
2012 organized by the IWA for the category Applied Research
(September 19th of 2012, Busan, Korea)
EUROPEAN PROJECT INNOVATION
AWARD RECEIVED IN BRUSSELS
After LIFE+
The After LIFE+ communication plan has the objective of ensuring that results
are effectively transferred and communicated, even after the end of the
project. This opens the door to the prospection and identification of future
opportunities and applications related to the field of biogas powered fuel cells.
For this purpose, CETaqua will focus in maintaining and prospecting new
relationships with all the related actors, and EMUASA will continue to run the
PEMFC pilot plant. In addition, website will be periodically maintained and
updated, with the latest relevant information.
27
CONCLUSIONS
LAYMAN’S REPORT
BIOCELL
CONCLUSIONS
The BIOCELL project has achieved the main goal of demonstrating the technical feasibility of energy production on WWTP from biogas via fuel cells.
The biogas treatment technologies are prepared to achieve the fuel cell
requirements. It is suggested to have a treatment line consisting in a main
contaminant removal, followed by a “polishing” or deep contaminant removal step. It is important to design robust treatment lines to avoid unexpected
shutdowns.
Comparing the two types of fuel cell tested, it has been observed that SOFC
seem to be more adapted for biogas applications. PEMFC need more basic
research regarding design issues. The lifetime and long-term performance
of such systems needs to be further assessed.
It has been demonstrated as well, that today fuel cells are still a very expensive technology for industrial implementation. New projects with direct
cooperation between biogas producers, biogas cleaning systems providers
and fuel cell manufacturers are necessary, both for scientific and industrial
purposes.
BIOGAS HOLDERS IN WWTP MURCIA ESTE
29
LAYMAN’S REPORT
2012
CETAQUA
WATER TECHNOLOGY CENTRE
Carretera d’Esplugues 75
08940 Cornellà de Llobregat,
Barcelona (Spain)
0034 93 312 48 00
[email protected]
www.life-biocell.eu