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 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 uses

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.

Zena Fly- Feeding the World on Insect

Meeting an ever increasing demand for food/feed/energy and managing waste have become two of the major global challenges. The global world population is estimated to increase from 7.3 billion in 2015 to 9.7 billion in 2050. Approximately one third of the global food produced for human composition is wasted. Currently, approximately 1.3 billion metric tons of waste are disposed with significant environmental impact as far as greenhouse gases and economic footprints and the current waste management practices are not costly sustainable.


Increase in Global Energy Demand

Global energy demand is estimated to increase from 524 Quadrillion btu in 2010, to 820 Quadrillion btu by 2040 (a 56% increase). Similarly, global demand of food and animal products are projected to increase by 70-100% and 50-70%, respectively, by 2050. To cope up with the demand for animal products, a substantial increase in nutritious animal feed is needed.

On one hand, the production of conventional feedstuff such as soybean meal and fish meal is reported as the major contributor to land occupation, ocean depletion, climate change, water and energy consumption. Moreover, such conventional animal feedstuff are not only limited in supply but also are becoming more expensive over the years. Additionally, there is an already strong and increasing competition for resources such as food, feed and biofuel production.

Need for alternative non-conventional source of food, feed, and fuel

Thus there is a pressing need for identifying and exploring the potential of alternative non-conventional source of food, feed, and fuel, which are economically viable, environmentally friendly, and socially acceptable.

By 2030 the Bio-based Economy is expected to have grown significantly. A pillar of this is biorefining, the sustainable processing of biomass into a spectrum of marketable products and energy. To satisfy this demand biorefineries need to be better integrated, flexible and operating more substantially. This means that a major yield, more efficient use of nutrients and water and greater pest and disease resistance should be achieve.

Zena Fly: A Startup Worth Watching

In this context an Italian-based start-up, Zena Fly, designed an innovative process for the future integrated biorefinery by mimicking nature’s ability. In fact, Zena Fly utilizes the natural insect life cycle to manage large quantity of organic waste produced in urban and industrial context, in order to generate sustainable and valuable by-products. The project of three young entrepreneurs foresees a combined bio-refinery where waste is turned into high-quality by-products by the anaerobic insect digestion.

The Concept

The basic concept is to convert waste into high-valuable products utilizing the black soldier flies (H. illucens), a now globally distributed insect. With a modern technique, the typical insect life cycle of these insects can be utilized in order to manage urban and industrial waste. The voracious larvae can reduce by more than 40-70% (based on the nature of the substrate-waste) the substrate where reared (waste) within 12-14 days.

From the anaerobic waste digestion, large quantity of fine protein meal for feed composition (more than 50-60% in protein), fat, fertilizing oil and other by-products of great interest such as chitin, and high-quality biofuel are then extracted.

Since the adult fly do not feed, and do not fly around for feeding, these animals are exceptionally valuable from a sanitary perspective (larvae has been demonstrate to reduce/eliminate E.coli and Salmonella).

Business Model

Zena Fly business model foresees to replicate their integrated biorefineries next to any waste management companies or industrial production areas where large quantity of waste need to be reduced and transformed. This is a win/win operation, where the waste management cost would be cut in half and the process will generate appealing opportunities for investments in a market where the increasing demand is already way higher than the products availability.

Zena Fly is now seeking for the right partner-investor in order to scale up quickly. For more information, please visit or email us on

Why Biofuels Should Be a Key Part in America’s Future

Biofuels are one of the hottest environmental topics, but they aren’t anything new. When discussing these fuels, experts frequently refer to first, second-and third-generation biofuels to differentiate between more efficient and advanced ones currently in development and more traditional biofuels in use for decades.

Biofuels are increasingly being used to power vehicles around the world

First-generation biofuels are things like methanol, ethanol, biodiesel and vegetable oil, while second-generation biofuels are produced by transforming crops into liquid fuels using highly advanced chemical processes, such as mixed alcohols and biohydrogen. Third-generation, or “advanced” biofuels, are created using oil that is made from algae or closed reactors and then refined to produce conventional fuels such as ethanol, methane, biodiesel, etc.

Cleaner Air and Less Impact on Climate Change

As biofuels come from renewable materials, they have less of an impact on climate change as compared to gasoline, according to multiple studies. Ethanol in gasoline has been helping to decrease smog in major cities, keeping the air cleaner and safer to breathe.

Starch-based biofuels can reduce carbon dioxide emissions by around 30- to 60-percent, as compared to gasoline, while cellulosic ethanol can lessen emissions even further, as much as 90 percent.

Reduced Danger of Environmental Disaster

Can you imagine buying one of the oceanfront Jacksonville condos in Florida, looking forward to enjoying peaceful beach strolls every morning only to find injured or killed animals and globs of oil all over the sand? Not exactly the vision of paradise you dreamed of.

A major benefit of using biofuels is the risk of environmental disaster is dramatically reduced. The 2010 Deepwater Horizon Spill that occurred in the Gulf of Mexico released millions of gallons of oil. It not only cost BP nearly $62 billion but caused extensive damage to wildlife and the environment. Biofuels are much safer. For example, a corn field won’t poison the ocean.

More Jobs and an Economic Boom

Numerous studies, including one conducted by the Renewable Fuels Association (RFA), have found that biofuels lead to more jobs for Americans. In 2014, the ethanol industry was responsible for nearly 84,000 direct jobs and over 295,000 indirect and induced jobs – all jobs that pay well and are non-exportable. The biofuels industry in the USA also added nearly $53 billion to the national GDP, $27 billion to the national GDP and over $10 billion in taxes, stimulating local, state and national economies.

Many experts predict that these figures will increase with significant job creation potential in biorefinery construction, operation and biomass collection. If the potential for producing cellulosic ethanol from household waste and forestry residues were utilized at commercial scale, even more jobs are likely to be added.

Energy Independence

When a nation has the land resources to grow biofuel feedstock, it is able to produce its own energy, eliminating dependence on fossil fuel resources. Considering the significant amount of conflict that tends to happen over fuel prices and supplies, this brings a net positive effect.

Biorefinery Prospects in India

India has a tremendous biomass potential which could easily be relied upon to fulfil most of our energy needs. An estimated 50 MMT (million metric tonnes) of liquid fuels are consumed annually in India, but with the actual biomass potential and its full utilization, India is capable of generating almost double that amount per annum. These biomass estimates only constitute the crop residues available in the country and essentially the second-generation fuels since the use of first-generation crop bases fuels in such food-starved nations is a criminal thought.


Existing Technologies

Currently, there are various technologies available to process such crop residues and generate value products from them. However, essentially, they all revolve around two main kinds of processes, either biochemical or thermal.

The biochemical process involves application of aerobic/anaerobic digestion for the production of biogas; or fermentation, which results in the generation of ethanol. Both these products could be subsequently treated chemically and through trans-esterification process, leading to production of biodiesel.

Alternatively, the thermochemical processes involve either the combustion, gasification or pyrolysis techniques, which produces heat, energy-rich gas and liquid fuels respectively. These products can be used as such, or could be further processed to generate high quality biofuels or chemicals.

The Need

The estimated organized energy breakup for India is 40 percent each for domestic and transport sectors and 20 percent for the industrial sectors. The current share of crude oil and gases is nearly 90 percent for the primary and transport sectors and the remaining 10 percent for the generation of industrial chemicals.

The fluctuating prices of crude oil in the international market and the resulting concern over energy security, has lead developing nations to explore alternative and cheap sources of energy to meet the growing energy demand. One of the promising solution for agrarian economies is Biorefinery.

The Concept

Biorefinery is analogous to the traditional petroleum refineries employing fractional distillation process for obtaining different fractions or components from the same raw material, i.e. the crude oil. Biorefinery involve the integration of different biomass treatment and processing methods into one system, which results in the production of different components from the same biomass.  This makes the entire chain more viable economically and also reduces the waste generated.

Typical Model of a Biorefinery

The outcome ranges from high-volume, low-energy content liquid fuels, which could serve the transportation industry needs, to the low-volume but high-value chemicals, which could add to the feasibility of such a project.

Steam and heat generated in the process could be utilized for meeting process heat requirements. By-products like chemicals, fertilizers, pharmaceuticals, polymers etc are also obtained which provide additional revenue streams.


Biorefineries can help in utilizing the optimum energy potential of organic wastes and may also resolve the problems of waste management and GHGs emissions. Wastes can be converted, through appropriate enzymatic/chemical treatment, into either gaseous or liquid fuels.

The pre-treatment processes involved in biorefining generate products like paper-pulp, HFCS, solvents, acetate, resins, laminates, adhesives, flavour chemicals, activated carbon, fuel enhancers, undigested sugars etc. which generally remain untapped in the traditional processes. The suitability of this process is further enhanced from the fact that it can utilize a variety of biomass resources, whether plant-derived or animal-derived.


The concept of biorefinery is still in early stages at most places in the world. Problems like raw material availability, feasibility in product supply chain, scalability of the model are hampering its development at commercial-scales. The National Renewable Energy Laboratory (NREL) of USA is leading the front in biorefinery research with path-breaking discoveries and inventions.

Although the technology is still in nascent stages, but it holds the key to the optimum utilization of wastes and natural resources that humans have always tried to achieve. The onus now lies on governments and corporate to incentivize or finance the research and development in this field.

Everything You Should Know About An Algae Biorefinery

High oil prices, competing demands between foods and other biofuel sources, and the world food crisis, have ignited interest in algaculture (farming of algae) for making vegetable oil, biodiesel, bioethanol, biogasoline, biomethanol, biobutanol and other biofuels. Algae can be efficiently grown on land that is not suitable for agriculture and hold huge potential to provide a non-food, high-yield source of biodiesel, ethanol and hydrogen fuels.


Several recent studies have pointed out that biofuel from microalgae has the potential to become a renewable, cost-effective alternative for fossil fuel with reduced impact on the environment and the world supply of staple foods, such as wheat, maize and sugar.

What are Algae?

Algae are unicellular microorganisms, capable of photosynthesis. They are one of the world’s oldest forms of life, and it is strongly believed that fossil oil was largely formed by ancient microalgae. Microalgae (or microscopic algae) are considered as a potential oleo-feedstock, as they produce lipids through photosynthesis, i.e. using only carbon, water, sunlight, phosphates, nitrates and other (oligo) elements that can be found in residual waters.

Oils produced by diverse algae strains range in composition. For the most part are like vegetable oils, though some are chemically similar to the hydrocarbons in petroleum.

Advantages of Algae

Apart from lipids, algae also produce proteins, isoprenoids and polysaccharides. Some strains of algae ferment sugars to produce alcohols, under the right growing conditions. Their biomass can be processed to different sorts of chemicals and polymers (Polysaccharides, enzymes, pigments and minerals), biofuels (e.g. biodiesel, alkanes and alcohols), food and animal feed (PUFA, vitamins, etc.) as well as bioactive compounds (antibiotics, antioxidant and metabolites) through down-processing technology such as transesterification, pyrolysis and continuous catalysis using microspheres.

Algae can be grown on non-arable land (including deserts), most of them do not require fresh water, and their nutritional value is high. Extensive R&D is underway on algae as raw material worldwide, especially in North America and Europe with a high number of start-up companies developing different options.

Most scientific literature suggests an oil production potential of around 25-50 ton per hectare per year for relevant algae species. Microalgae contain, amongst other biochemical, neutral lipids (tri-, di-, monoglycerides free fatty acids), polar lipids (glycolipids, phospholipids), wax esters, sterols and pigments. The total lipid content in microalgae varies from 1 to 90 % of dry weight, depending on species, strain and growth conditions.

What is Algae Biorefinery

In order to develop a more sustainable and economically feasible process, all biomass components (e.g. proteins, lipids, carbohydrates) should be used and therefore biorefining of microalgae is very important for the selective separation and use of the functional biomass components.

The term algae biorefinery was coined to describe the production of a wide range of chemicals and biofuels from algal biomass by the integration of bio-processing and appropriate low environmental impact chemical technologies in a cost-effective and environmentally sustainable.

If biorefining of microalgae is applied, lipids should be fractionated into lipids for biodiesel, lipids as a feedstock for the chemical industry and essential fatty acids, proteins and carbohydrates for food, feed and bulk chemicals, and the oxygen produced can be recovered as well.

The potential for commercial algae production, also known as algaculture, is expected to come from growth in translucent tubes or containers called photo bioreactors or in open systems (e.g. raceways) particularly for industrial mass cultivation or more recently through a hybrid approach combining closed-system pre-cultivation with a subsequent open-system.

Advantages of Algae Biorefinery

The major advantages of an algae biorefinery include:

  • Use of industrial refusals as inputs ( CO2,wastewater and desalination plant rejects)
  • Large product basket with energy-derived (biodiesel, methane, ethanol and hydrogen) and non-energy derived (nutraceutical, fertilizers, animal feed and other bulk chemicals) products.
  • Not competing with food production (non-arable land and no freshwater requirements)
  • Better growth yield and lipid content than crops.

Indeed, after oil extraction the resulting algal biomass can be processed into ethanol, methane, livestock feed, used as organic fertilizer due to its high N:P ratio, or simply burned for energy cogeneration (electricity and heat). If, in addition, production of algae is done on residual nutrient feedstock and CO2, and production of microalgae is done on large scale in order to lower production costs, production of bulk chemicals and fuels from microalgae will become economically, environmentally and ethically extremely attractive.