Hydrogen sulfide in biogas: Generation and abatement guide

 

Hydrogen sulfide in biogas: Generation and abatement guide

Hydrogen sulfide (H₂S) is a natural byproduct of the anaerobic digestion process in biogas production. During this process, organic matter is broken down by microorganisms in the absence of oxygen. H₂S is formed when sulfur-containing compounds in the feedstock are reduced. Here’s a brief overview of how this happens:

Sources of Hydrogen Sulfide in Biogas:

1. Sulfur-Containing Feedstock:
• Organic materials such as manure, sewage sludge, food waste, and agricultural residues often contain sulfur compounds (e.g., proteins, sulfates, and sulfites).
• During anaerobic digestion, these sulfur compounds are converted into H₂S.
2. Sulfate-Reducing Bacteria (SRB):
• SRB, such as Desulfovibrio and Desulfotomaculum, play a key role in H₂S formation.
• These bacteria reduce sulfates (SO₄²⁻) and other sulfur compounds to H₂S in the absence of oxygen:

3. Decomposition of Organic Sulfur Compounds:
• Proteins and amino acids (e.g., cysteine and methionine) in the feedstock are broken down by hydrolytic and acidogenic bacteria, releasing H₂S.

Factors Influencing H₂S Formation:

1. Feedstock Composition:
• High sulfur content in feedstock (e.g., manure, certain industrial wastes) leads to higher H₂S production.
2. Digester Conditions:
• pH: Neutral to slightly alkaline conditions favour H₂S formation.
• Temperature: Mesophilic (30-40°C) and thermophilic (50-60°C) conditions can influence microbial activity and H₂S production.
• Retention Time: Longer retention times may increase H₂S formation.
3. Microbial Activity:
• The presence and activity of sulfate-reducing bacteria (SRB) directly impact H₂S levels.

Hydrogen sulfide formation in biogas is a natural process driven by the breakdown of sulfur-containing compounds during anaerobic digestion. Proper management and treatment are essential to mitigate its negative effects and ensure safe biogas utilization.

Below are some of the process widely used for abatement of hydrogen sulfide in the industry.

1.      Chelated Iron Process:

The Chelated Iron Process is a chemical method used for biogas desulfurization, specifically to remove hydrogen sulfide (H₂S) from biogas. This process is particularly useful in anaerobic digestion systems, where biogas produced contains H₂S, which is corrosive and harmful to equipment and the environment. The chelated iron process is efficient, cost-effective, and environmentally friendly.

How the Chelated Iron Process Works:

1.      Oxidation of H₂S:

o   Biogas containing H₂S is passed through a scrubbing solution containing chelated iron (Fe³⁺).

o  The chelated iron acts as an oxidizing agent, converting H₂S into elemental sulfur (S⁰) and water (H₂O):

2.      Regeneration of Chelated Iron:

o   The reduced iron (Fe²⁺) is then regenerated back to its oxidized form (Fe³⁺) by introducing oxygen (air) into the solution:

o  This regeneration step allows the chelated iron solution to be reused, making the process sustainable.

 

3.      Sulfur Recovery:

o   The elemental sulfur formed during the process is separated from the solution, typically by filtration or settling.

o   The recovered sulfur can be further processed or disposed of safely.

 

Key Features of the Chelated Iron Process:

·        High Efficiency: Capable of removing >99% of H₂S from biogas.

·        Selective: Targets H₂S without affecting other biogas components like methane (CH₄).

·        Regenerative: The chelated iron solution is continuously regenerated and reused.

·        Environmentally Friendly: Converts H₂S into non-toxic elemental sulfur, which can be reused or safely disposed of.

·        Operational Flexibility: Can handle varying H₂S concentrations and biogas flow rates.

 The chelated iron process is a reliable and sustainable solution for biogas desulfurization, ensuring compliance with environmental regulations and protecting downstream equipment from H₂S-related damage.

 

2.      Alkali Scrubbing for Biogas Desulfurization

Alkali scrubbing is a chemical process used to remove hydrogen sulfide (H₂S) from biogas. It involves passing biogas through an alkaline solution, such as sodium hydroxide (NaOH), or sodium carbonate (Na₂CO₃), which reacts with H₂S to form non-volatile compounds.

a.      Key Points:

                                                       i.      Reaction:      H₂S reacts with the alkali to form sulphides or bisulfides:

 

b.      Process:

                                                       i.      Biogas is introduced into a scrubbing tower bottom where alkali solution is sprayed from the top of the column, in a counter-current flow for better contact. These counter-current columns are typical of the packed type.

                                                      ii.      H₂S is absorbed and chemically converted, leaving the biogas clean.

c.       Advantages:

                                                       i.      High H₂S removal efficiency (up to 99%).

                                                      ii.      Simple and cost-effective for small to medium-scale applications.

                                                    iii.      Can be regenerated in some systems.

d.      Disadvantages:

                                                       i.      Alkali consumption requires periodic replenishment.

                                                      ii.      Spent solution disposal or treatment is needed.

                                                    iii.      pH control is critical for optimal performance.

e.      Applications:

                                                       i.      Used in biogas upgrading for renewable natural gas (RNG), wastewater treatment, and agricultural/industrial biogas systems.

                                                      ii.      Alkali scrubbing is a reliable and efficient method for biogas desulfurization, ensuring safe and clean biogas for energy use.

 

3.      Ferrosorp-Based Biogas Desulfurization

Ferrosorp is a dry desulfurization method that uses iron oxide (Fe₂O₃) or iron hydroxide (Fe(OH)₃) based adsorbents to remove hydrogen sulfide (H₂S) from biogas. It is a simple, cost-effective, and widely used technique, especially for small to medium-scale biogas systems.

Key Points:

1.      Mechanism:

o   H₂S reacts with iron oxide/hydroxide to form iron sulfide (FeS) or iron disulfide (FeS₂):

o   The reaction is irreversible, and the adsorbent is consumed over time.

2.      Process:

o   Biogas is passed through a bed of Ferrosorp material (e.g., pellets or granules).

o   H₂S is adsorbed and chemically bound, leaving the biogas clean.

3.      Advantages:

o   Simple and easy to operate with no liquid waste.

o   High H₂S removal efficiency (up to 99%).

o   Low maintenance and suitable for small-scale applications.

4.      Disadvantages:

o   Adsorbent is consumed and needs periodic replacement.

o   Limited capacity for high H₂S concentrations or large biogas volumes.

o   Spent material requires proper disposal.

5.      Applications:

o   Commonly used in agricultural biogas plants, small-scale digesters, and wastewater treatment facilities.

Ferrosorp-based desulfurization is a reliable and efficient method for removing H₂S from biogas, ensuring safe and clean biogas for energy production

 

4.      Biochemical Process:

The Biological Desulfurization Process, is a sustainable and efficient method for removing hydrogen sulfide (H₂S) from biogas using sulfur-oxidizing bacteria. This process is widely used in anaerobic digestion systems, landfill gas treatment, and other biogas-producing facilities. It is an environmentally friendly alternative to chemical desulfurization methods.

 

How the Process Works:

1.      Absorption of H₂S:

o   Biogas containing H₂S is introduced into a scrubber (e.g., a packed column or bubble column).

o The H₂S is absorbed into an alkaline scrubbing solution (typically sodium hydroxide, NaOH, or sodium carbonate, Na₂CO₃), forming a sulfide-rich solution:

2.      Biological Oxidation:

o   The sulfide-rich solution is transferred to a bioreactor containing sulfur-oxidizing bacteria (e.g., Thiobacillus species).

o   These bacteria oxidize the sulfide (HS⁻) to elemental sulfur (S⁰) or sulfate (SO₄²⁻) in the presence of oxygen:

o   The process can be controlled to favour the production of elemental sulfur, which is easier to handle and has commercial value.

o   The scrubbing solution, now free of sulfide, is regenerated and recycled back to the absorber for reuse.

3.      Sulfur Recovery:

o   Elemental sulfur is separated from the bioreactor effluent by settling or filtration.

o   The recovered sulfur can be used as a raw material in various industrial applications or agricultural applications.

 Key Features of the Biochemical Scrubbing Process:

·        High Efficiency: Removes >99% of H₂S from biogas.

·        Environmentally Friendly: Uses natural biological processes and produces minimal waste.

·        Cost-Effective: Low operating costs due to the use of renewable biological catalysts.

·        Selective: Targets H₂S without affecting methane (CH₄) or other biogas components.

·        Flexible: Can handle varying H₂S concentrations and biogas flow rates.

 Every biogas purification process has an optimal operating range where the total cost of ownership (TCO) is minimized. This optimal range varies depending on the biogas flow rate and hydrogen sulfide (H₂S) concentration. Key factors influencing H₂S removal technology selection are the H₂S loading and downstream processing requirements.

To assist in technology selection, we've developed a guide that recommends the solution with the lowest TCO. Our TCO calculation includes capital expenses and operating costs projected over a 20-year plant lifespan. We advise users to focus on the trends in TCO (calculated using our provided formula) rather than absolute numbers, as the trends remain consistent regardless of the specific calculation method.

For a free copy of our technology selection program, please visit www.avenirenergia.net or contact us at info.ocen@yahoo.com.

 

BiogaSmart-PWS: A Revolutionary Leap in Biogas Purification

Harnessing the Power of Innovation

We are proud to introduce BiogaSmart-PWS, a cutting-edge, patented smart biogas purification technology (Patent Number 555135). This revolutionary solution is designed to elevate the efficiency and reliability of biogas purification processes to unprecedented levels.

Unmatched Performance and Reliability

BiogaSmart-PWS offers a compelling array of features and benefits:

• Unmatched Methane Recovery:
  • Achieve up to a remarkable 99% methane recovery rate, maximizing energy yield from biogas.
• Consistent High-Purity Methane:
  • Delivering a minimum of 96% pure methane 24/7/365, ensuring consistent and reliable performance, regardless of operational conditions.
• Ultra-Pure CO2:
  • Produce up to 99% pure biogenic CO2 (moisture-free) at the regeneration package vent, ideal for various industrial applications, such as enhanced oil recovery (EOR) and greenhouse gas reduction initiatives.
• Zero Air Contamination:
  • Unlike traditional technologies, BiogaSmart-PWS employs advanced techniques to prevent air intrusion into the product stream, maintaining product purity and optimizing energy output.
• Smart Predictive Control (SPC):
  • Benefit from minimal operator intervention and reduced human error with our sophisticated control system. SPC continuously monitors and adjusts system parameters, ensuring optimal performance and efficiency.
• Microbial-Free Regeneration:
  • Eliminate the need for frequent cleaning and maintenance with our microbial-free regeneration package, saving time, labor, and costs.
• Foolproof Operation:
  • Our system is designed to withstand operator errors, ensuring continuous operation even in unexpected situations. This robust design minimizes downtime and maximizes productivity.

The Future of Biogas Purification

BiogaSmart-PWS represents a significant advancement in biogas purification technology. By addressing the limitations of traditional methods, this innovative solution offers a sustainable and cost-effective approach to harnessing the full potential of biogas.

We are committed to driving innovation and sustainability. By leveraging cutting-edge technology, we are empowering industries to maximize the benefits of biogas, reduce their environmental impact, and contribute to a greener future. 

For Additional Information feel free to connect at info.ocen@yahoo.com and +91 8600008213 or just drop a ping vai contact form.

Compressed biogas price - INR per kg or INR per MMBTU ? How it compare with each other.

 

The Compressed Biogas or Biomethane is mostly sold or purchased at a value equivalent to a kilogram of gas complying with IS16087:2016 Rev 1 as of date. Looking at the global trend and energy pricing in India we are valuing the gas based on energy content i.e. INR per MMBTU. The latest rate as per OMC is about INR 1470 per MMBTU and an additional INR 2 per Kg for direct pipe injection or INR 8 per kg for Injection via Cascade. The compression charges per kg will be calculated on which basis needs to be explored. We expect these numbers to be converted to identical energy units of INR per MMBTU for simplicity in near future. 

There are a lot of discussions happening in and around this and we strongly felt to elaborate on this so that all the stakeholders of this value chain lower down will be able to evaluate the various gas prices via different selling options to the common level before taking call for a product off-take mechanism.

Let’s quantify the energy value of CBG first and then convert various forms for better understanding.

The Energy of CBG is mainly from methane and the balance of the gasses is mostly fillers. The GCV of the pure methane is about 55.5 MJ/kg or 13265 Kcal/kg. 

As per IS 16087:2016 Rev 1 the appx.  96% v/v Methane, 3.5% Carbon Dioxide, up to 0.5% Oxygen, up to 20 mg/m3 Hydrogen sulfide and 5 mg/m3 water.  The composition here is on a volumetric basis and once converted to a weight basis the methane is estimated to be about 90% w/w of the CBG.

The appx energy value of CBG is about 11938.5 Kcal/kg or about 8955 Kcal/sm3 at an estimated density of about 0.75 kg/sm3 w.r.t. above mentioned specification.

1 BTU is equivalent to 0.252 Kcal. Or 1 MMBTU is about 252164 Kcal and with 11938.5 Kcal per KG CBG it can be estimated that each MMBTU will have about 252164/11938.5 i.e. 21.12 unit.

So with the given specification of CBG and further calculation, there are 21.12 kg CBG per MMBTU of the energy. Now let's convert about gas pricing in the same units for better understanding.

               The base price of the gas: 1470 Rs/MMBTU

               Compression Cost: 21.12 x 2 : 42.24 Rs/MMTU (Direct Injection or Via DCU in Nearest Line) ---1

               Compression Cost: 21.12 x 8 : 168.96 Rs/MMTU (Sale at nearest Retail outlet via Cascade in Nearest Line)---2

The landed price of the gas per kg to the developer will be 71.60 Rs/kg of CBG in direct injection case and 77.6 Rs/kg of CBG in Injection via Cascade in the nearest line.

Please note these values are specific to gas composition at the outlet of the gas purification plant so to make it simple we have developed an excel program. Please connect with us for a free copy of the program. A screenshot of the same is attached herewith for reference.

Cow dung for CBG production: Opportunity and challenges in India

India is a country with a rich history and with a very special connection to agriculture in our hearts. Agriculture is one of the prominent pillars of the Indian economy over the centuries. As it evolved over the years, animal husbandry became an integral part of Indian farmer's income. As per data about 150 to 200 million animals actively contribute to the Indian farmer’s household income in various ways and provide them with a decent cash flow in times of uncertainties apart from value-added fertilizer to the farms.

Cattle dung is one of the readily available household items across the country and fulfilling the requirement of fuels and fertilizer over the years. The dung is basically a partially digested portion of relatively hard-to-digest components from food. The actual specification is highly dependent on the type of food they eat and the purpose of the animal milking or non-milking ones etc but not limited to. It is a privilege to come from a farming background with a close association with dairy at home and working in Biogas in the recent past developed a decent level of confidence to put some data on cow dung and its potential.

The chemical composition of cow dung is mainly cellulose, Hemicellulose and lignin portion of the food with rich flora of healthy ruminococcus micro-organisms. It is the perfect mix for generation of biogas and it might be the reason it energized millions of household over the years in india and across the globe at small, medium and large scale over the years. For a simplicity one can call cow dung a perfectly pretreated lignocellulosic feedstock for biogas production which generally gives really good digestion efficiency on ground. Typically dung has about 15-20% w/w dry matter with 50-60% volatile solid, balance lignin and Ash. Once can expect 50-60% digestion efficiency of the key constituent which result in the yield of 40-50 sm3/MT of as it cow dung.

A significant portion of cow dung stored in open undergoes rapid digestion to form very good manure which make it one of the most value-added fertilizer rich in NPK and soil conditioner. At the same time this also make it one of the prominent source of GHG emission in the world with a significant contribution and which is quite alarming. All the efforts world putting in toward 1.5 Degree target and dung can not be ignored. The common practice of using cow dung due to highly decentralized production is making Upla or Dry Fuel which serve as a source of heat to rural households apart from stocking at the place and using as fertilizer multiple times a year. This activity contributes to GHG emissions and demands more scientific ways of extracting energy from it via biogas generation. The government of India's policy for Biogas highly encourages this route at every scale of biogas generation.

Cow dung is seen one of the largest sources of compressed biogas in Indian and across the globe considering bioenergy production while protecting the environment and at the same time providing value-added organic fertilizer to boost farmer’s income. India over 25 MMT of recoverable dung can shoulder a responsibility to protect the environment while recovering the CBG and biofertilizers which will have significant forex saving. The CBG value chain and the government is providing all required assistance for the conversion of cow dung to CBG and fertilizer.

For any CBG project availability, access and affordability of the potential feedstock are key attribute which will make the project viable and sustainable. The project which are viable and sustainable will drive agricultural economy in a long term by actively contributing the farmer’s income while solving the environmental & energy issues of the country. As CBG is been pushed really hard by government in a very positive sense, most of the bulk generator looking at this as an opportunity for generating assured income in longer horizon. This actually pushed the feedstock prices at very challenging level at some cases where viability of a project is in jeopardy.

Here I would like to present a simple math for all the key stakholders of the value chain to think about the value of the dung w.r.t. product and given a choice I will not be surprised to hear the feedstock pricing roadmap from authorities in line with sugar policy which arrive a Fair price depending on the final output and its market value which make the feedstock a win-win proposition to all the stakeholders.  

Let’s take cow dung as a case but it equally applies to all the Feedstocks. A typical CBG potential of the cow dung is about 16-20 kg/ MT as per IS 16087:2016 Rev 1. The market price of the CBG/CNG at Delhi is about INR 80 per kg at some point of time (say) which estimated to result in revenue of about 1300 to 1600 Rs per MT of Cow dung. The avg cost of conversion on account of power, Operation and maintenance, transport, administrative and miscellaneous expense is about Rs. 15-20 translate to about 300 to 400 Rs/MT of cow dung. The above Number will left arrive at about 900 to 1200 per MT when gas sold by B2C method of product evacuation. If the product is sold at SATAT Base rate then 500 to 700 is left which suppose to suffice the cost of feedstock and pay for loan for capital investment ensuring a adequate profit which make this a viable business case for any developer.

For CBG business the total cost of production more than 55% of the Revenues from Gas and Fertilizers looking at present business value chain from feedstock sourcing to product evacuation make really tough call to take by any developer. The values could be here and there but the trend is worth to be noted which demands a logical rationale to arrive at a fair value for feedstock with long term visibility to make CBG a fuel of the future moving forward. Any addition to this is welcome from all of you so that we would be putting fact to the table which will empower developers to take informed decision on right mix of feedstock for their proposed business ventures.  

  

How Big is the Pressmud opportunity for CBG production in India?

 

A.      Background:

The article is intended to enlighten the availability of press mud for CBG production in India and competition from alternate usage today and tomorrow.

The press mud is combination of two world press and mud which has a history attached to it. The sugar cane juice after extraction from cane undergo pasteurization process to disinfect any presence of bacterial infection before further processing. The Sterilized juice then treated for removal of mud, organic precipitates which come along the juice extraction process apart from high molecular weight complex sugars which will interfere in production of sugar at later stage of the processing. It literally means the mud recovered from juice clarification is mechanically pressed to recovery maximum possible sugar from it in equipment called Rotary vacuum filter (R.V.F.). The press mud is also called as “maili” in Hindi which means soil contaminated stream. R.V.F. is widely used equipment which needs addition of bagasilo as filter Aid traditionally which are fine bagasse particles which impart cellulose and hemicellulose fractions in Pressmud. These fraction are the only digestible fraction apart from residual sugar in it which is explored for generation of biogas in recent past.

There is one more method rose to fame of mud separation by decanter which due to its inherent limitation haven not received well by most of the sugar factories which separate the mud without requirement of any filter Aid and pressmud from such sugar factories known to yield negligible biogas in various runs by researchers at various levels.

 

B.      Pressmud Production trends and Present usage

The Indian avg sugar production in recent past is about 30-32 MMT and Our sugar cane crushing is about 350-400 MMT on about 500 sugar factories across India. The values could vary here and there a bit but the trend will prevail mostly. The Indian in house sugar consumption is about 25-26 MMT and by an average we used to have roughly 6-7 MMT of sugar is in excess every year in recent past till govt allowed the production of Ethanol under EBP and farmer cane arrear issues built-up apart from cash outflow on export subsidy.

The average pressmud production as per production at 3.5 to 4% w/w of the crushing will stand at 12 to14 MMT per annum.

The most prominent use of pressmud in the history and at present is for bio-composting distillery spent wash which limited the Ethanol production over the years and NGT actions leading to push for ZLD in distillery which is one of the most polluting red category industry.

India has more than 350 distilleries producing about 5-6 Billion liters of Ethanol from sugar bearing feedstock which lead to about 50-60 Billion liters of effluent for disposal.

In recent past Ethanol production has grown mainly on account of incineration boiler for ZLD which reduced requirement of pressmud for composting. Roughly 1-1.5-Billion-liter capacity has Incineration boiler and balance are having Biomethanation route of ZLD with Composting. The effluent disposal of about 4 to 4.5 billion liters worth production literally needs about 10-11 billion liter effluent disposal and at 1-1.5 composting ratio it demands 8-11 MMT pressmud. Which is largely equal to total production in India.

As most of the distilleries shifting to non-composting sustainable route of effluent Managment due PCB pressure and need for increased production due to push from Govt for EBP the pressmud is gradually freeing up. There is slight stagnancy in the plant going for incineration boiler in recent past due to drastic reduction in effluent generation due to use of high sugar bearing fractions from sugar mill for production of Ethanol. This situation lead to impact on economic viability of incineration boiler as a mode of ZLD and exploration of other mode of ZLD a need of the hour.

At the same time spent wash nutrients must go back to sugar cane fields because major nutrient is Potassium which is in abundance in spent wash. Unfortunately India has 100% import of potassium in the tune of 2.5 to 3 million Mt. We have about 5.3 million hectors of Area under cane plantation. The avg. potassium requirement of plant is about 90 to 100 kg/Ha which translate to about 0.53 million Mt i.e. about 20% of the import could be saved by effective use of spent wash as a fertilizer via bio-compost or any other rout of recycling spent wash to cane fields.

As most of the consumption is for composting in their own distillery or offtake by some standalone distillery unit in some cases never ever stressed / posed press mud as a disposal issue and if some small quantity demand disposal then storage in yard for 20-30 days reduces its volume by 1/3^rd which reduced the scale of issue as off now.

So with this back ground whosoever speaks to sugar industry they will not project pressmud as issue due to in-house consumption avenues and excess if any at location could be used for building relation with farmer by giving it to them as Fertlizer.

However, spent wash bio-composting is still a mode of spent wash disposal than fertilizer production facility. The profitable ways of fertilizer offtake and marketing is still a challenge to address to the greater extent.

As the mud portion is coming from Farm and anyways goes back to farm as humus after composting.  The bagasilo portion which is Actually part of bagasse has organic which could be converted to biogas which slightly difficult ways than selling it as fuel in local brick kilns in UP and other part of India was a regular affair for disposal as offtake was always been issue for bulk quantities until NGT crackdown on such kilns on pollution aspect in northern India.

As more and more distillery will shift to non-composting based ZLD routes pressmud will gradually open up and build as issue for disposal if not converted to Biogas in coming time.

The surplus sugar has potential to produce about 3.5 to 4.5 Billion liter of Ethanol as of now where as our requirement based on NITI Aayog projection will be over 10 Billion liters which need a serious after though about feedstock’s and technology if our internal sugar consumption not gone down to free up the extra sugar or innovative farming technology which will increase the sugar cane yield for EBP in near future which looks one of the major challenge and hurdle in the Ethanol boom to sustain in near future.

 

C.      Future usage of Pressmud and facts

EBP is been significant part of Indian energy dashboard in recent part and industries along with technology suppliers looking out to various feedstock which could be potentially converted to Ethanol or liquid biofuel economically.

Pressmud could be converted to pellets for combustion after drying by small sugar factories is near future due to restriction on composting and unviability of CBG plant due to viable capacity. Pressmud like high ash fuels will pose its own challenges in disposal for sure but due to disproportionate increase in coal prices use of pressmud for fuel gained lot of traction in recent past. How sustainable way of utilizing pressmud is to be seen in near future with overall impact of environment.

Bagasse could be one of the potential product moving forward can be converted to CBG as Power PPA has seen downward trends in recent past and no significant upward movement is expected in time to come. However existing investment in co-generation plants will largely limit this shift considering majority of investment in cogeneration plants is on BOOT basis. The avg available free bagasse in today’s scenario is about 10-20 MMT which is mostly used as fuel, paper and board manufacturing India at on date.

As paper and board are value selling products can afford cost variations apart from fuel application at some locations so overall project economics will drive its conversion to various byproducts in near future. The is possibility of conversion of bagasse to 2G ethanol at prohibitive price for private investor as on date and any update moving forward will be interesting to watch out. These value are really good indicator for industry to chalk out the business goals in near and immediate future.

I personally feel use of pressmud and bagasse to extract maximum value by converting it to CBG for mills would be potential option to evaluate.

 

D.      Conclusion and Recommendations moving forward

a.       Pressmud will pose major disposal issue in near future if not converted to value added co-product such as CBG by sugar industry.

b.       Pressmud  and bagasse to Ethanol using 2G Biomass to Ethanol technology being lignocellulose based substrate and overall process will be distance possibility and troublesome due to handling and investment number in such technology.

c.       Pressmud will be available more and more in coming future as NGT will tight grip on red category industry looking at present ZLD technology credentials apart from Slop fired boilers which is largely a known devil in ethanol industry. 

UTTAR PRADESH STATE BIOENERGY POLICY 2022: CATALYST IN ENERGY SUSTAINABILITY

 

Uttar Pradesh was one of the flag bearers in the Indian Bioenergy sector. The government has always extended its helping hand to bioenergy entrepreneurs over the year. Most prominent is its bioenergy policy in 2014 which was eventually updated in 2018. Now in 2022 Govt. of UP has issued its latest Bioenergy policy focusing on businesses around the agriculture industry which will eventually contribute to farmer income enhancement and employment to the locals apart from encouraging entrepreneurship development.

This policy will benefit proposed / upcoming units along with the capacity expansion of existing units. The policy covers the entire value chain from the development of feedstock to product utilization. The assured feedstock is one of the key imperatives for any CBG plant addressed in this policy via entire supply chain development using barren land utilization for the production of energy crops which would be used as feedstock for CBG production. The subsidy provision for mechanization of feedstock production, collection, and storage via Farmer Producer companies will eventually ensure a steady supply of feedstock to CBG plants and also ensure steady income to farmers in that area with periodic cash flow as against other agricultural products but not limited to. The assured support for evacuation of biofertilizers to farmers via the existing fertilizer value chain of the government of UP.

The govt is committed to offering financial support of total 700 cars over the next 5 years which will suppose to build CBG's production capacity of appx. 1000 TPD. This support is apart from expenditure on approach road and supply chain development efforts.

Major Highlights of the UP State Bioenergy policy are as below,

1.       Subsidy benefits

a.       Capex Subsidy for plant based on the production of CBG is offered for plant developers who have LOI and EOI for the development of the plant. As per policy about 75 lakhs per ton of CBG production for plant and machinery, basic infrastructure, and utility-related investments. This subsidy does not cover expenditures on land and administrative investments. The max subsidy per plant is limited to 20 Cr.

b.       Feedstock aggregator will get an additional 30% subsidy up to 20 lakhs over and above the subsidy of the central government mission for agricultural mechanization scheme. As per the central scheme, all aggregators can get up to 50% of the Capex subsidy.

c.       All subsidies shall be deposited to the plant/unit bank account after COD ( Date of Commercial operation of the plant).

2.       Duty Benefits

a.       Electricity duty benefit – All CBg projects shall get 100% exemption in electricity duty for 10 years from the date of COD.

b.       Stamp Duty – All Stamp duty expenses on rent, lease, and sales of land for plant and feedstock storage, etc.

c.       Development charges exemption as applicable by respective development authorities.

3.       Other Benefits – All units over 50 Cr investment will be offered the facility of approach road up to 5 KM from the plant as applicable by Govt.

UPNEDA will be the noddle agency for these projects all related matters for the policy duration. All units with LOI and EOI from OMC can register themselves under this scheme and the required documents are as below,

a.       Application form

b.       Company registration certificate/documents as applicable

c.       Share the certificate of the company

d.       Last three financial year balance sheet. For startup companies financial credentials of the mother/parent group to be submitted.

e.       Detailed Pre-feasibility report of the project

f.        Non-refundable Registration fees of INR 10,000/- per plant in the form of a demand draft.

The plant developer shall provide the following documents within three months of registration for authority approval.

a.       Detailed Project Report (DPR)

b.       Biomass / Feedstock assessment report

c.       Land documents

d.       Project planning report with timelines of critical milestones.

e.       Water availability/allotment documents as applicable.

f.        NOC of local development authority as applicable.

All developers shall submit performance security for about 3% of the investment of the plant as per DPR estimates. The implementation agreement shall be done after depositing the performance security. The plant construction shall be completed within 2 years from the implementation agreement. Any extension to this  shall be a maximum of 2 months if the said delay is due to reasons beyond the control of the developer and duly certified by the noddle agency.

The developer will be allotted up to 10 acres of the land for the processing plant and up to 25 acres of the land for feedstock storage and handling for a period up to 30 years. All duties regarding land shall be exempted during the policy tenure.

Noddle agency will facilitate the CBG plant value chain from feedstock allotment to infrastructural support for Bio-fertilizer sale apart for the local dispensing station for CBG evacuation. For more details kindly refer to detailed UP Bioenergy Policy 2022 document at http://upneda.org.in/

Press Mud is a potential fuel of the future and sustainable Fertilizer.

 

The Indian sugar industry is like the Kalpvriksha as during its processing yields products and co-products which has significant values in the market. Over the year utilization pattern of these products has undergone significant change due to various reasons in and around the sugar industry. The prices of sugar can been traditionally decided by the Indian sugar policy and as of now its is FRP based system which effectively linked to sugar recovery via various means / products like sugar, sugar syrup, molasses B-heavy grade etc but not limited to. As per Indian sugar policy latest edition the revenue from sugar and its co-products such as bagasse, Molasses, and Pressmud shall be shared with farmers. The Indian biofuel policy 2018 and its subsequent amendment / update enabled Indian sugar industry to use its products and co-product in more productive ways than before . This collectively contributed to increase in farmers income in quite significant way in recent past.
Almost all the co-product from sugar mill are used quite innovatively which somehow linked to the national interest of energy requirement at one end and the farmers income enhancement on other. Sugar, Molasses and Bagasse added significant value to Indian sugar industry over the years. Whereas another co-product which is slightly underutilized so far in content to extent of value other product added.
Pressmud which is commonly known as filter cake or press cake in sugar industry. It is residue of juice clarification process where main product is clear juice and impurities settled at bottom then filtered traditionally using rotary vacuum filter. In rotary vacuum filter all best possible efforts for recovery of sugar is made and final filtered residue is called filter cake or press cake. Typical generation of pressmud is about 3-5 to 4+% w/w of the cane crushing capacity of the mill. During this filtration process bagasilo is added as filter aid which is nothing but fine bagasse particle made this method of filtration very popular in the sugar mill due to no additional expenses of filter aid. In recent past there are some mills who tried using centrifugal decanter for separation of mud /cake from juice clarification process but due to multiple reasons it fail to impress the industry.
Press mud is basically a mud i.e. dirt and good amount of bagasilo and inorganic impurity courtesy to clarification process in sugar mill. Way back when distilleries were only used for potable alcohol production majority of pressmud was distributed to farmers who used it as organic fertilizer in sugar cane fields. When the when Ethanol was projected as Biofuel and various schemes to push to enhance production Ethanol then bio-composting using press mud as prominent substrate is gain boost as method of zero liquid discharge apart from other measure to ensure the zero pollution from distilleries. Evacuation of bio-fertilizers was one the major challenge in this method of spent wash treatment which in most of the cases became expense to such industries rather than became value added co-product. It might have solved the sugar mill press mud evacuation issue but it just got shifted to distilleries. The multifold increase in sugar mill capacities changed the dynamics of the press mud utilization in recent past. As a result which was supposed to be one of the potential co-product confined to as intermediate which generally transferred from sugar mill to some way of utilization or treatment at either unsold value or notional value.
As govt of India drafted a biofuel policy in 2018 for both liquid and gaseous fraction of green, clean and indigenous biofuel which will significantly contribute to countries energy security. Compressed biogas was seen one of the major gaseous biofuel which will solve multiple national issues and convert them to opportunity. The government of India has launched the SATAT ( Sustainable alternative toward affordable transportation) program which will target setting up about 5000 Compressed Biogas plant which potentially suffice the natural gas requirement to the greater extent while solving pollution issue of country.
The SATAT program enabled Indian entrepreneur to come up with innovative ways of extracting biogas from low value raw materials and covert them to value added co-products like fuel and fertilizers. As mentioned in my previous article ( link- https://www.linkedin.com/pulse/feedstocks-compressed-natural-gas-production-bharat-kadu/) the best possible feedstock for biogas / Compressed biogas Gas (CBG) Production shall have following attribute but not limited to.
1.      Higher Window of availability
2.      Ease of Access and assured supply
3.      Minimal Transport and handling requirement
4.      Decent Yield of product and by-product
5.      Relatively Ease of conversion
6.      Benefit to society and their involvement in the process
Looking at feedstock under consideration press mud became one the most popular choice of the project developers even though there is huge push for rice straw and other agri residue.
At present sugar industry encashed Pressmud whenever opportunity is there on an average value of 100-400 Rs/MT which is about 4 to 16 Rs/MT of cane crushed. IF this Pressmud is used in bio-composting with Pressmud then Pressmud contribution of fertilizer is appx. 200-250 kg per MT of press mud used and average Bio-Composting selling price is 700-1000 Rs/MT which results in appx value realization of about 140 to 400 Rs/MT excluding cost of production which is generally higher than the selling price as prime objective manufacturing such biofertilizers is compliance to Zero liquid discharge requirement of distillery effluent not the production of fertilizer.
In recent past due to exponential increase in coal prices the cheaper alternative demand has gone up significantly. The Pressmud in some cases is sun dried and converted to pellets which can substitute some of the high cost fuel in short term resulted in demand for Pressmud for the application other than bio-composting.
One ton of average specification of press mud if converted to CBG then appx. 40 kg or CBG is produced along with about 110-130 kg of solid biofertilizers and 500-700 lit of liquid fertilizer. The Solid fertilizer market selling price is about 2.5 to 3.0 Rs/Kg and as per latest CBG pricing & Retail selling prices of CNG one can expect min 65 Rs/kg for CBG as safe bet. The Revenues from such conversion adds up to about 3000 Rs/MT of Pressmud. The potential revenue from press mud to CBG could be about 120 Rs/MT of Cane crushing which is significantly higher than what we are getting as on of now.
The better value utilization of Pressmud will definitely resulting in significant increase in farmer’s income if the benefits passed on to farmer ensuring sustainable CBG manufacturing business which will result in win-win for all the stockholder of the value chain.
Please note these are just estimated number which moving forward needs to be evaluated for specific case which will largely cover the situation in most of the mills of India.
This will enable all sugar mills to become a true bio-refinery which will be significant pillar of Indian food and energy security apart from connecting millions of farmers to building nation which is self-sufficient and making India the Next Super power.