Miscanthus: Reducing the Establishment Costs

Miscanthus-Elephant-GrassMiscanthus has been lauded as a dynamic high potential biomass crop for some time now due to its high yields, low input requirements and perennial nature. Miscanthus is commonly used as a biomass fuel to produce heat and electricity through combustion, but studies have found that miscanthus can produce similar biogas yields to maize when harvested at certain times of the year.  Miscanthus is a C4 grass closely related to maize and sugarcane, it can grow to heights of three metres in a single growing season.

High Establishment Costs

However, high establishment costs have impeded the popularity of the crop. High establishment costs of miscanthus are as a result of the sterile nature of the crop, which means that miscanthus cannot be propagated from seed and instead must be propagated from vegetative material. The vegetative material commonly used is taken from the root structure known as rhizomes; rhizome harvesting is a laborious process and when combined with low multiplication rates, results in a high cost for miscanthus rhizomes. The current figure based on Irish figures is €1,900 ha for rhizomes.

Promising Breakthrough

Research conducted in Teagasc Oak Park Carlow Ireland, suggests that there may be a cost effective of method of propagating miscanthus by using the stem as the vegetative material rather than having to dig up expensive rhizomes. The system has been proven in a field setting over two growing seasons and plants have been shown to be perennial.

A prototype planter suitable for commercial up scaling has been developed to sow stem segments of miscanthus. Initial costs are predicted at €130 ha for plant material. The image below shows the initial stem that was planted in a field setting and the shoots, roots, and rhizome developed by the stem at the end of the first growing season.

miscanthus-stem

Feedstock for AD Plants

Switching from maize to miscanthus as a feedstock for anaerobic digestion plants would increase profitability and boost the GHG abatement credentials of the systems. Miscanthus is a perennial crop which would provide a harvest every year once established for 20 years in a row without having to be replanted compared to maize which is replanted every year. This would provide an obvious economic saving as well as allowing carbon sequestration in the undisturbed soil.

There would be further GHG savings from the reduced diesel consumption required for the single planting as opposed to carrying out heavy seedbed cultivation each year for maize. Miscanthus harvested as an AD feedstock would also alleviate soil compaction problems associated with maize production through an earlier harvest in more favourable conditions.

Future Perspectives

Miscanthus is a nutrient efficient crop due to nutrient cycling. With the onset of senescence nutrients in the stem are transferred back to the rhizome and over-wintered for the following year’s growth. However the optimum date to harvest biomass to produce biogas is before senescence. This would mean that a significant proportion of the plants nutrient stores would be removed which would need to be replaced. Fertiliser in the form of digestate generated from a biogas plant could be land spread to bridge nutrient deficiencies. However additional more readily available chemical N fertiliser may have to be applied.

Some work at Oak Park on September harvested miscanthus crops has seen significant responses from a range of N application rates. With dwindling subsidies to support anaerobic digestion finding a low cost perennial high yielding feedstock could be key to ensuring economic viability.

Energy Access to Refugees

refugee-camp-energyThere is a strong link between the serious humanitarian situation of refugees and lack of access to sustainable energy resources. According to a 2015 UNCHR report, there are more than 65.3 million displaced people around the world, the highest level of human displacement ever documented. Access to clean and affordable energy is a prerequisite for sustainable development of mankind, and refugees are no exception. Needless to say, almost all refugee camps are plagued by fuel poverty and urgent measure are required to make camps livable.

Usually the tragedy of displaced people doesn’t end at the refugee camp, rather it is a continuous exercise where securing clean, affordable and sustainable energy is a major concern. Although humanitarian agencies are providing food like grains, rice and wheat; yet food must be cooked before serving. Severe lack of modern cook stoves and access to clean fuel is a daily struggle for displaced people around the world. This article will shed some light on the current situation of energy access challenges being faced by displaced people in refugee camps.

Why Energy Access Matters?

Energy is the lifeline of our modern society and an enabler for economic development and advancement. Without safe and reliable access to energy, it is really difficult to meet basic human needs. Energy access is a challenge that touches every aspect of the lives of refugees and negatively impacts health, limits educational and economic opportunities, degrades the environment and promotes gender discrimination issues. Lack of energy access in refugee camps areas leads to energy poverty and worsen humanitarian conditions for vulnerable communities and groups.

Energy Access for Cooking

Refugee camps receive food aid from humanitarian agencies yet this food needs to be cooked before consumption. Thus, displaced people especially women and children take the responsibility of collecting firewood, biomass from areas around the camp. However, this expose women and minors to threats like sexual harassments, danger, death and children miss their opportunity for education. Moreover, depleting woods resources cause environmental degradation and spread deforestation which contributes to climate change. Moreover, cooking with wood affects the health of displaced people.

Access to efficient and modern cook stove is a primary solution to prevent health risks, save time and money, reduce human labour and combat climate change. However, humanitarian agencies and host countries can aid camp refugees in providing clean fuel for cooking because displaced people usually live below poverty level and often host countries can’t afford connecting the camp to the main grid. So, the issue of energy access is a challenge that requires immediate and practical solutions. A transition to sustainable energy is an advantage that will help displaced people, host countries and the environment.

Energy Access for Lighting

Lighting is considered as a major concern among refugees in their temporary homes or camps. In the camps life almost stops completely after sunset which delays activities, work and studying only during day time hours. Talking about two vulnerable groups in the refugees’ camps “women and children” for example, children’s right of education is reduced as they have fewer time to study and do homework. For women and girls, not having light means that they are subject to sexual violence and kidnapped especially when they go to public restrooms or collect fire woods away from their accommodations.

Rationale For Sustainable Solutions

Temporary solutions won’t yield results for displaced people as their reallocation, often described as “temporary”, often exceeds 20 years. Sustainable energy access for refugees is the answer to alleviate their dire humanitarian situation. It will have huge positive impacts on displaced people’s lives and well-being, preserve the environment and support host communities in saving fuel costs.  Also, humanitarian agencies should work away a way from business as usual approach in providing aid, to be more innovative and work for practical sustainable solutions when tackling energy access challenge for refugee camps.

UN SDG 7 – Energy Access

The new UN SDG7 aims to “ensure access to affordable, reliable, sustainable and modern energy for all”. SDG 7 is a powerful tool to ensure that displaced people are not left behind when it comes to energy access rights. SDG7 implies on four dimensions: affordability, reliability, sustainability and modernity. They support and complete the aim of SDG7 to bring energy and lightening to empower all human around the world. All the four dimensions of the SDG7 are the day to day challenges facing displaced people. The lack of modern fuels and heavy reliance on primitive sources, such as wood and animal dung leads to indoor air pollution.

Energy access touches every aspect of life in refugee camps

Energy access touches every aspect of life in refugee camps

For millions of people worldwide, life in refugee camps is a stark reality. Affordability is of concern for displaced people as most people flee their home countries with minimum possessions and belongings so they rely on host countries and international humanitarian agencies on providing subsidized fuel for cooking and lightening. In some places, host countries are itself on a natural resources stress to provide electricity for people and refugees are left behind with no energy access resources. However, affordability is of no use if the energy provision is not reliable (means energy supply is intermittent).

Parting Shot

Displaced people need a steady supply of energy for their sustenance and economic development. As for the sustainability provision, energy should produce a consistent stream of power to satisfy basic needs of the displaced people. The sustained power stream should be greater than the resulted waste and pollution which means that upgrading the primitive fuel sources used inside the camp area to the one of modern energy sources like solar energy, wind power, biogas and other off-grid technologies.

For more insights please read this article Renewable Energy in Refugee Camps 

Renewable Energy in Refugee Camps

dabaab-refugee-campAccess to clean and affordable energy is a prerequisite for sustainable development of mankind, and refugees are no exception. Refugee camps across the world house more than 65 million people, and almost all refugee camps are plagued by fuel poverty. Needless to say, urgent measure are required to make camps livable and sustainable.

Rapid advancements in renewable energy technologies have made it possible to deploy such systems on various scales.  The scalability potential of renewable energy systems makes them well-suited for refugee camps, especially in conflict-afflicted areas of the Middle East, Asia and Africa.

Renewable energy in refugee camps can be made available in the form of solar energy, biomass energy and wind energy. Solar panels, solar cooking units, solar lanterns, biomass cookstoves and biogas plants are some of the popular renewable energy technologies that can improve living standards in refugee camps. It is important to focus on specific needs of refugees and customization of technology towards local conditions. For example, solar technologies are better understood than biogas systems in Jordan.

Solar Energy

Solar energy can provide long-term resilience to people living in refugee camps. With many camps effectively transformed into full-fledged towns and cities, it is essential to harness the power of sun to run these camps smoothly. Solar cookers, solar lanterns and solar water heaters are already being used in several refugee camps, and focus has now shifted to grid-connected solar power projects. The 5MW Azraq solar project is the world’s first grid-connected renewable energy project to be established in a refugee camp. The project is being funded entirely by Ikea through the Brighter Lives for Refugees campaign. The program, now in its third year, seeks to improve the lives of refugees around the world by providing access to sustainable energy supplies.

Biomass Energy

Due to lack of land and resources, refugee camps puts tremendous pressure on natural vegetation, especially supply of fuel wood to camp-dwellers. Replacement of traditional stoves with efficient biomass-fired cook stoves can save as much as 80% of cooking fuel. Instead of wood, it would be also be a good option to use agricultural wastes, like husk and straw. Another interesting proposition for refugee camps is to set up small-scale DIY biogas plants, based on human wastes and food residuals. The biogas produced can be used as a cooking medium as well as for power/heat generation.

Wind Energy

Small wind turbines can also play a key role in providing energy to dwellers of refugee camps. Such turbines are used for micro-generation and can provide power from 1kW to 300kW. Majority of small wind turbines are traditional horizontal axis wind turbines but vertical axis wind turbines are a growing type of wind turbine in the small wind market. Small wind turbines are usually mounted on a tower to raise them above any nearby obstacles, and can sited in refugee camps experiencing wind speeds of 4m/s or more.

Solar lights in Azraq Refugee Camp (Jordan)

Solar lights in Azraq Refugee Camp (Jordan)

Conclusions

Renewable energy systems have the potential to improve living standards in refugee camps and ease the sufferings of displaced and impoverished communities. Solar panels, biogas system, biomass stoves and micro wind turbines are some of the renewable energy systems that can be customized for refugee camps and transform them into a less harsh place for displaced people.

Role of Biomass Energy in Rural Development

biomass-balesBiomass energy systems not only offer significant possibilities for clean energy production and agricultural waste management but also foster sustainable development in rural areas. The increased utilization of biomass wastes will be instrumental in safeguarding the environment, generation of new job opportunities, sustainable development and health improvements in rural areas.

Biomass energy has the potential to modernize the agricultural economy and catalyze rural development. The development of efficient biomass handling technology, improvement of agro-forestry systems and establishment of small, medium and large-scale biomass-based power plants can play a major role in rural development.

Sustainable harvesting practices remove only a small portion of branches and tops leaving sufficient biomass to conserve organic matter and nutrients. Moreover, the ash obtained after combustion of biomass compensates for nutrient losses by fertilizing the soil periodically in natural forests as well as fields.

Planting of energy crops on abandoned agricultural lands will lead to an increase in species diversity. The creation of structurally and species diverse forests helps in reducing the impacts of insects, diseases and weeds. Similarly the artificial creation of diversity is essential when genetically modified or genetically identical species are being planted.

Improvements in agricultural practices promises to increased biomass yields, reductions in cultivation costs, and improved environmental quality. Extensive research in the fields of plant genetics, analytical techniques, remote sensing and geographic information systems (GIS) will immensely help in increasing the energy potential of biomass feedstock.

Rural areas are the preferred hunting ground for the development of biomass sector worldwide. By making use of various biological and thermal processes (anaerobic digestion, combustion, gasification, pyrolysis), agricultural wastes can be converted into biofuels, heat or electricity, and thus catalyzing sustainable development of rural areas economically, socially and environmentally.

Biomass energy can reduce 'fuel poverty' in remote and isolated communities

Biomass energy can reduce ‘fuel poverty’ in remote and isolated communities

A large amount of energy is utilized in the cultivation and processing of crops like sugarcane, wheat and rice which can met by utilizing energy-rich residues for electricity production. The integration of biomass-fueled gasifiers in coal-fired power stations would be advantageous in terms of improved flexibility in response to fluctuations in biomass availability and lower investment costs.

There are many areas in India where people still lack access to electricity and thus face enormous hardship in day-to-day lives. Biomass energy promises to reduce ‘fuel poverty’ commonly prevalent among remote and isolated communities.  Obviously, when a remote area is able to access reliable and cheap energy, it will lead to economic development and youth empowerment.

Waste Management Perspectives for Military

waste-management-militaryWaste management has a profound impact on all sections of the society, and military is no exception. With increasing militarization, more wars and frequent armed conflicts, protection of the environment has assumed greater significance for military in armed conflicts as well as peacetime operations. Tremendous amount of waste is generated by military bases and deployed forces in the form of food waste, papers, plastics, metals, tires, batteries, chemicals, e-waste, packaging etc.

War on Waste

Sustainable management of waste is a good opportunity for armed forces to promote environmental stewardship, foster sustainable development and generate goodwill among the local population and beyond. Infact, top military bases in the Western world, like Fort Hood and Fort Meade, have an effective strategy to counter the huge amount of solid waste, hazardous waste and other wastes generated at these facilities.

Waste management at military bases demands an integrated framework based on the conventional waste management hierarchy of 4Rs – reduction, reuse, recycling and recovery (of energy). Waste reduction (or waste minimization) is the top-most solution to reduce waste generation at military bases which demands close cooperation among different departments, including procurement, technical services, housing, food service, personnel. Typical waste reduction strategies for armed forces includes

  • making training manuals and personnel information available electronically
  • reducing all forms of packaging waste
  • purchasing products, such as food items, in bulk
  • purchasing repairable, long-lasting and reusable items

Due to large fraction of recyclables in the waste stream, recycling is an attractive proposition for the armed forces. However, environmental awareness, waste collection infrastructure, and modern equipment are essential for the success of any waste management strategy in a military installation. Food waste and yard waste (or green waste) can be subjected to anaerobic digestion or composting to increase landfill diversion rates and obtain energy-rich biogas (for cooking/heating) and nutrient-rich fertilizer (for landscaping and gardening). For deployed forces, small-scale waste-to-energy systems, based on thermal technologies, can be an effective solution for disposal of combustible wastes, and for harnessing energy potential of wastes.

Key Aspect

Management options for military installations is dependent on size of the population, location, local regulations, budgetary constraints and many other factors. It is imperative on base commanders to evaluate all possible options and develop a cost-effective and efficient waste management plan. The key factors in the success of waste management plan in military bases are development of new technologies/practices, infrastructure building, participation of all departments, basic environmental education for personnel and development of a quality recycling program.

Military installations are unique due to more than one factor including strict discipline, high degree of motivation, good financial resources and skilled personnel. Usually military installations are one of the largest employers in and around the region where they are based and have a very good influence of the surrounding community, which is bound to have a positive impact on overall waste management strategies in the concerned region.

Description of a Biogas Power Plant

A biogas plant is a decentralized energy system, which can lead to self-sufficiency in heat and power needs, and at the same time reduces environmental pollution. The components of a modern biogas (or anaerobic digestion) plant include: manure collection, anaerobic digester, effluent treatment, gas storage, and gas use/electricity generating equipment. The fresh animal manure is stored in a collection tank before its processing to the homogenization tank which is equipped with a mixer to facilitate homogenization of the waste stream. The uniformly mixed waste is passed through a macerator to obtain uniform particle size of 5-10 mm and pumped into suitable-capacity anaerobic digesters where stabilization of organic waste takes place.

In anaerobic digestion, organic material is converted to biogas by a series of bacteria groups into methane and carbon dioxide. The majority of commercially operating digesters are plug flow and complete-mix reactors operating at mesophilic temperatures. The type of digester used varies with the consistency and solids content of the feedstock, with capital investment factors and with the primary purpose of digestion.

Biogas contain significant amount of hydrogen sulfide (H2S) gas which needs to be stripped off due to its highly corrosive nature. The removal of H2S takes place in a biological desulphurization unit in which a limited quantity of air is added to biogas in the presence of specialized aerobic bacteria which oxidizes H2S into elemental sulfur.

Gas is dried and vented into a CHP unit to a generator to produce electricity and heat. The size of the CHP system depends on the amount of biogas produced daily. The digested substrate is passed through screw presses for dewatering and then subjected to solar drying and conditioning to give high-quality organic fertilizer. The press water is treated in an effluent treatment plant based on activated sludge process which consists of an aeration tank and a secondary clarifier. The treated wastewater is recycled to meet in-house plant requirements. A chemical laboratory is necessary to continuously monitor important environmental parameters such as BOD, COD, VFA, pH, ammonia, C:N ratio at different locations for efficient and proper functioning of the process.

The continuous monitoring of the biogas plant is achieved by using a remote control system such as Supervisory Control and Data Acquisition (SCADA) system. This remote system facilitates immediate feedback and adjustment, which can result in energy savings.

Waste to Energy Conversion Routes

Teesside-WTE-plantWaste-to-energy is the use of modern combustion and biological technologies to recover energy from urban wastes. There are three major waste to energy pathways – thermochemical, biochemical and physico-chemical. Thermochemical conversion, characterized by higher temperature and conversion rates, is best suited for lower moisture feedstock and is generally less selective for products. On the other hand, biochemical technologies are more suitable for wet wastes which are rich in organic matter.

Thermochemical Conversion

The three principal methods of thermochemical conversion are combustion in excess air, gasification in reduced air, and pyrolysis in the absence of air. The most common technique for producing both heat and electrical energy from wastes is direct combustion. Combined heat and power (CHP) or cogeneration systems, ranging from small-scale technology to large grid-connected facilities, provide significantly higher efficiencies than systems that only generate electricity.

WTE_Pathways

Combustion technology is the controlled combustion of waste with the recovery of heat to produce steam which in turn produces power through steam turbines. Pyrolysis and gasification represent refined thermal treatment methods as alternatives to incineration and are characterized by the transformation of the waste into product gas as energy carrier for later combustion in, for example, a boiler or a gas engine. Plasma gasification, which takes place at extremely high temperature, is also hogging limelight nowadays.

Biochemical Conversion

Biochemical processes, like anaerobic digestion, can also produce clean energy in the form of biogas which can be converted to power and heat using a gas engine. Anaerobic digestion is the natural biological process which stabilizes organic waste in the absence of air and transforms it into biofertilizer and biogas. Anaerobic digestion is a reliable technology for the treatment of wet, organic waste.  Organic waste from various sources is biochemically degraded in highly controlled, oxygen-free conditions circumstances resulting in the production of biogas which can be used to produce both electricity and heat.

In addition, a variety of fuels can be produced from waste resources including liquid fuels, such as ethanol, methanol, biodiesel, Fischer-Tropsch diesel, and gaseous fuels, such as hydrogen and methane. The resource base for biofuel production is composed of a wide variety of forestry and agricultural resources, industrial processing residues, and municipal solid and urban wood residues. Globally, biofuels are most commonly used to power vehicles, heat homes, and for cooking.

Physico-chemical Conversion

The physico-chemical technology involves various processes to improve physical and chemical properties of solid waste. The combustible fraction of the waste is converted into high-energy fuel pellets which may be used in steam generation. The waste is first dried to bring down the high moisture levels. Sand, grit, and other incombustible matter are then mechanically separated before the waste is compacted and converted into pellets or RDF. Fuel pellets have several distinct advantages over coal and wood because it is cleaner, free from incombustibles, has lower ash and moisture contents, is of uniform size, cost-effective, and eco-friendly.

Food Waste Management – Consumer Behavior and FWDs

food-waste-managementFood waste is a global issue that begins at home and as such, it is an ideal contender for testing out new approaches to behaviour change. The behavioural drivers that lead to food being wasted are complex and often inter-related, but predominantly centre around purchasing habits, and the way in which we store, cook, eat and celebrate food.

Consumer Behavior – A Top Priority

Consumer behaviour is a huge priority area in particular for industrialised nations – it is estimated that some western societies might be throwing away up to a third of all food purchased. The rise of cheap food and convenience culture in recent years has compounded this problem, with few incentives or disincentives in place at producer, retail or consumer level to address this.

While it is likely that a number of structural levers – such as price, regulation, enabling measures and public benefits – will need to be pulled together in a coherent way to drive progress on this agenda, at a deeper level there is a pressing argument to explore the psycho-social perspectives of behaviour change.

Individual or collective behaviours often exist within a broader cultural context of values and attitudes that are hard to measure and influence. Simple one-off actions such as freezing leftovers or buying less during a weekly food shop do not necessarily translate into daily behaviour patterns. For such motivations to have staying power, they must become instinctive acts, aligned with an immediate sense of purpose. The need to consider more broadly our behaviours and how they are implicated in such issues must not stop at individual consumers, but extend to governments, businesses and NGOs if effective strategies are to be drawn up.

Emergence of Food Waste Disposers

Food waste disposer (FWDs), devices invented and adopted as a tool of convenience may now represent a unique new front in the fight against climate change. These devices, commonplace in North America, Australia and New Zealand work by shredding household or commercial food waste into small pieces that pass through a municipal sewer system without difficulty. The shredded food particles are then conveyed by existing wastewater infrastructure to wastewater treatment plants where they can contribute to the generation of biogas via anaerobic digestion. This displaces the need for generation of the same amount of biogas using traditional fossil fuels, thereby averting a net addition of greenhouse gases (GHG) to the atmosphere.

The use of anaerobic digesters is more common in the treatment of sewage sludge, as implemented in the U.K., but not as much in the treatment of food waste. In addition to this, food waste can also replace methanol (produced from fossil fuels) and citric acid used in advanced wastewater treatment processes which are generally carbon limited.

Despite an ample number of studies pointing to the evidence of positive impacts of FWDs, concerns regarding its use still exist, notably in Europe. Scotland for example has passed legislation that bans use of FWDs, stating instead that customers must segregate their waste and make it available curbside for pickup. This makes it especially difficult for the hospitality industry, to which the use of disposer is well suited. The U.S. however has seen larger scale adoption of the technology due to the big sales push it received in the 1950s and 60s. In addition to being just kitchen convenience appliances, FWDs are yet to be widely accepted as a tool for positive environmental impact.

Note: Note: This excerpt is being published with the permission of our collaborative partner Be Waste Wise. The original excerpt and its video recording can be found at this link

Biogas Plants at Akshaya Patra Kitchens

Akshaya-Patra-Kitchen-BioGasThe Akshaya Patra Foundation, a not-for-profit organization, is focused on addressing two of the most important challenges in India – hunger and education. Established in year 2000, the Foundation began its work by providing quality mid-day meals to 1500 children in 5 schools in Bangalore with the understanding that the meal would attract children to schools, after which it would be easier to retain them and focus on their holistic development. 14 years later, the Foundation has expanded its footprint to cover over 1.4 million children in 10 states and 24 locations across India.

The Foundation has centralised, automated kitchens that can cook close to 6,000 kilos of rice, 4.5 to 5 tonnes of vegetables and 6,000 litres of sambar, in only 4 hours. In order to make sustainable use of organic waste generated in their kitchens, Akshaya Patra Foundation has set up anaerobic digestion plants to produce biogas which is then used as a cooking fuel. The primary equipment used in the biogas plants includes size reduction equipment, feed preparation tank for hydrolysis of waste stream, anaerobic digester, H2S scrubber and biogas holder.

Working Principle

Vegetable peels, rejects and cooked food waste are shredded and soaked with cooked rice water (also known as ganji) in a feed preparation tank for preparation of homogeneous slurry and fermentative intermediates. The hydrolyzed products are then utilized by the microbial culture, anaerobically in the next stage. This pre-digestion step enables faster and better digestion of organics, making our process highly efficient.

The hydrolyzed organic slurry is fed to the anaerobic digester, exclusively for the high rate biomethanation of organic substrates like food waste. The digester is equipped with slurry distribution mechanism for uniform distribution of slurry over the bacterial culture. Optimum solids are retailed in the digester to maintain the required food-to-microorganism ratio in the digester with the help of a unique baffle arrangement. Mechanical slurry mixing and gas mixing provisions are also included in the AD design to felicitate maximum degradation of organic material for efficient biogas production. After trapping moisture and scrubbing off hydrogen sulphide from the biogas, it is collected in a gas-holder and a pressurized gas tank. This biogas is piped to the kitchen to be used as a cooking fuel, replacing LPG.

Basic Design Data and Performance Projections

Waste handling capacity 1 ton per day cooked and uncooked food waste with 1 ton per day ganji water

Input Parameters                      

Amount of solid organic waste 1000 Kg/day
Amount of organic wastewater ~ 1000 liters/day ganji (cooked rice water)

Biogas Production

Biogas production ~ 120 – 135 m3/day

Output Parameters

Equivalent LPG to replace 50 – 55 Kg/day (> 2.5 commercial LPG cylinders)
Fertilizer (digested leachate) ~ 1500 – 2000 liters/day

Major Benefits

Modern biogas installations are providing Akshaya Patra, an ideal platform for managing organic waste on a daily basis. The major benefits are:

  • Solid waste disposal at kitchen site avoiding waste management costs
  • Immediate waste processing overcomes problems of flies, mosquitos etc.
  • Avoiding instances when the municipality does not pick up waste, creating nuisance, smell, spillage etc.
  • Anaerobic digestion of Ganji water instead of directly treating it in ETP, therefore reducing organic load on the ETPs and also contributing to additional biogas production.

The decentralized model of biogas based waste-to-energy plants at Akshaya Patra kitchens ensure waste destruction at source and also reduce the cost incurred by municipalities on waste collection and disposal.

akshayapatra-kitchen

An on-site system, converting food and vegetable waste into green energy is improving our operations and profits by delivering the heat needed to replace cooking LPG while supplying a rich liquid fertilizer as a by-product.  Replacement of fossil fuel with LPG highlights our organization’s commitment towards sustainable development and environment protection.

The typical ROI of a plug and play system (without considering waste disposal costs, subsidies and tax benifts) is around three years.

Future Plans

Our future strategy for kitchen-based biogas plant revolves around two major points:

  • Utilization of surplus biogas – After consumption of biogas for cooking purposes, Akshaya Patra will consider utilizing surplus biogas for other thermal applications. Additional biogas may be used to heat water before boiler operations, thereby reducing our briquette consumption.
  • Digested slurry to be used as a fertilizer – the digested slurry from biogas plant is a good soil amendment for landscaping purposes and we plan to use it in order to reduce the consumption of water for irrigation as well as consumption of chemical fertilizers.

Trends in Utilization of Biogas

The valuable component of biogas is methane (CH4) which typically makes up 60%, with the balance being carbon dioxide (CO2) and small percentages of other gases. The proportion of methane depends on the feedstock and the efficiency of the process, with the range for methane content being 40% to 70%. Biogas is saturated and contains H2S, and the simplest use is in a boiler to produce hot water or steam.

The most common use is where the biogas fuels an internal combustion gas engine in a Combined Heat and Power (CHP) unit to produce electricity and heat. In Sweden the compressed gas is used as a vehicle fuel and there are a number of biogas filling stations for cars and buses. The gas can also be upgraded and used in gas supply networks. The use of biogas in solid oxide fuel cells is also being researched.

Biogas can be combusted directly to produce heat. In this case, there is no need to scrub the hydrogen sulphide in the biogas. Usually the process utilize dual-fuel burner and the conversion efficiency is 80 to 90%. The main components of the system are anaerobic digester, biogas holder, pressure switch, booster fan, solenoid valve, dual fuel burner and combustion air blower.

The most common method for utilization of biogas in developing countries is for cooking and lighting. Conventional gas burners and gas lamps can easily be adjusted to biogas by changing the air to gas ratio. In more industrialized countries boilers are present only in a small number of plants where biogas is used as fuel only without additional CHP. In a number of industrial applications biogas is used for steam production.

Burning biogas in a boiler is an established and reliable technology. Low demands are set on the biogas quality for this application. Pressure usually has to be around 8 to 25 mbar. Furthermore it is recommended to reduce the level of hydrogen sulphide to below 1 000 ppm, this allows to maintain the dew point around 150 °C.

CHP Applications

Biogas is the ideal fuel for generation of electric power or combined heat and power. A number of different technologies are available and applied. The most common technology for power generation is internal combustion. Engines are available in sizes from a few kilowatts up to several megawatts. Gas engines can either be SI-engines (spark ignition) or dual fuel engines. Dual fuel engines with injection of diesel (10% and up) or sometimes plant oil are very popular in smaller scales because they have good electric efficiencies up to guaranteed 43%.

The biogas pressure is turbo-charged and after-cooled and has a high compression ratio in the gas engines. The cooling tower provides cooling water for the gas engines. The main component of the system required for utilizing the technology are anaerobic digester, moisture remover, flame arrester, waste gas burner, scrubber, compressor, storage, receiver, regulator, pressure switch and switch board.

Gas turbines are an established technology in sizes above 500 kW. In recent years also small scale engines, so called micro-turbines in the range of 25 to 100kW have been successfully introduced in biogas applications. They have efficiencies comparable to small SI-engines with low emissions and allow recovery of low pressure steam which is interesting for industrial applications. Micro turbines are small, high-speed, integrated power plants that include a turbine, compressor, generator and power electronics to produce power.

New Trends

The benefit of the anaerobic treatment will depend on the improvement of the process regarding a higher biogas yield per m3 of biomass and an increase in the degree of degradation. Furthermore, the benefit of the process can be multiplied by the conversion of the effluent from the process into a valuable product. In order to improve the economical benefit of biogas production, the future trend will go to integrated concepts of different conversion processes, where biogas production will still be a significant part. In a so-called biorefinery concept, close to 100% of the biomass is converted into energy or valuable by-products, making the whole concept more economically profitable and increasing the value in terms of sustainability.

Typical layout of a modern biogas facility

One example of such biorefinery concept is the Danish Bioethanol Concept that combines the production of bioethanol from lignocellulosic biomass with biogas production of the residue stream. Another example is the combination of biogas production from manure with manure separation into a liquid and a solid fraction for separation of nutrients. One of the most promising concepts is the treatment of the liquid fraction on the farm-site in a UASB reactor while the solid fraction is transported to the centralized biogas plant where wet-oxidation can be implemented to increase the biogas yield of the fiber fraction. Integration of the wet oxidation pre-treatment of the solid fraction leads to a high degradation efficiency of the lignocellulosic solid fraction.