Biogas Generator

Biogas is a renewable, as well as a clean, source of energy. Gas generated through biodigestion is Biogas is a renewable, as well as a clean, source of energy. Gas generated through biodigestion is non-polluting; it actually reduces greenhouse emissions (i.e. reduces the greenhouse effect). No combustion takes place in the process, meaning there is zero emission of greenhouse gasses into the atmosphere; therefore, using gas from waste as a form of energy is a great way to combat global warming.

Unsurprisingly, concern for the environment is a major reason why the use of biogas has become more widespread. Biogas plants significantly curb the greenhouse effect: the plants lower methane emissions by capturing this harmful gas and using it as fuel. Biogas generation helps cut reliance on the use of fossil fuels, such as oil and coal.

Another biogas advantage is that unlike other types of renewable energies, the process to create the gas is natural, not requiring energy for the generation process. In addition, the raw materials used in the production of biogas are renewable, as trees and crops will continue to grow. Manure, food scraps, and crop residue are raw materials that will always be available, which makes it a highly sustainable option.

Overflowing landfills don’t only spread foul smells- they also allow toxic liquids to drain into underground water sources.

Subsequently, another advantage of biogas is that biogas generation may improve water quality. Moreover, anaerobic digestion deactivates pathogens and parasites; thus, it’s also quite effective in reducing the incidence of waterborne diseases. Similarly, waste collection and management significantly improve in areas with biogas plants. This in turn, leads to improvements in the environment, sanitation, and hygiene.

The by-product of the biogas generation process is enriched organic digestate, which is a perfect supplement to, or substitute for, chemical fertilizers. The fertilizer discharge from the digester can accelerate plant growth and resilience to diseases, whereas commercial fertilizers contain chemicals that have toxic effects and can cause food poisoning, among other things.

The technology used to produce biogas is quite cheap. It is easy to set up and needs little investment when used on a small scale. Small biodigesters can be used right at home, utilizing kitchen waste and animal manure. A household system pays for itself after a while and the materials used for generation are absolutely free. The gas produced can be used directly for cooking and generation of electricity. This is what allows the cost of biogas production to be relatively low.

Farms can make use of biogas plants and waste products produced by their livestock every day. The waste products of one cow can provide enough energy to power a lightbulb for an entire day.

In large plants, biogas can also be compressed to achieve the quality of natural gas and utilized to power automobiles. Building such plants requires relatively low capital investment and creates green jobs. For instance, in India, 10 million jobs were created, mostly in rural areas, in plants and in organic waste collection.

Biogas generators save women and children from the daunting task of firewood collection. As a result, more time is left for cooking and cleaning. More importantly, cooking on a gas stove, instead of over an open fire, prevents the family from being exposed to smoke in the kitchen. This helps prevent deadly respiratory diseases. Sadly, 4.3 million people a year die prematurely from illnesses attributed to the household air pollution caused by the inefficient use of solid fuels for cooking.

The application of biogas to electricity generation is the most common of all uses. Biogas made from plant material offers a renewable way to generate electricity. Unlike solar power available only during the day or wind power made only intermittently, biogas uses a reliable field crop grown and harvested by farmers.

Biogas possesses chemical energy, and therefore electricity from biogas comes as a result of converting this chemical energy to mechanical energy and finally into electricity. This is done by the use of transducers such as generators and turbines that convert energy from one form to another. This electricity can be used both domestically and commercially since it can be made in small and large scale.

Connect the biogas source to the inlet of the gas engine. The biogas source may be a cylinder that contains pressurized gas or directly from a digester, which is the means of decomposing the organic material. The gas engine is designed to work in a similar manner to that of a car, since it is composed of pistons within which the gas is burnt and used to rotate a shaft, converting the chemical energy in the biogas into mechanical energy through motion.

Connect the gas engine to the AC generator in such a way that the rotating shaft powers the AC generator. The motion transferred to the AC generator produces electricity through magnetism.

The application of biogas to produce combined heat and power should be as common as electricity generation, but the additional CHP plant requires additional investment, so the add-on equipment needed to use the waste heat may not be installed. Whenever that happens it should be seen as a missed opportunity. There is almost always a use to which the heat can be put, from electricity generation. Energy which would otherwise have to be wasted to the air around the cooling fans.

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.

Theoretically, biogas can be converted directly into electricity by using a fuel cell. However, this process requires very clean gas and expensive fuel cells. Therefore, this option is still a matter for research and is not currently a practical option. The conversion of biogas to electric power by a generator set is much more practical.

To understand the application of biogas as a fuel added into fossil fuel natural gas supply pipelines, needs to be explained.

When purified to a suitable extent to be injected in a natural gas pipeline, the pure gas is usually called “biomethane”. Biomethane injected in this way is in demand in many countries where the population is keen to comply with climate change reduction methods. The gas industry calls the compressed biomethane “Renewable Natural Gas” or RNG.

According to figures from the Coalition for Renewable Natural Gas, of more than 1,000 landfills that could be candidates for biogas production, only 42 high-BTU landfill gas-to-energy projects are producing RNG, biomethane, upgraded or pipeline-quality biogas.

Local gas distribution and transmission pipeline companies are increasingly being approached to purchase and/or take delivery of renewable natural gas (RNG) into their existing lines for general distribution. RNG is derived from anaerobic decomposition of a wide variety of organic materials, including dairy and agricultural waste and wastewater and landfill sources.

Within the natural gas industry, the term ‘biogas’ refers to gas produced directly from digesters or landfills; it is often burned on or off-site in generators for conversion to electricity or simply flared. Cleaned biogas or biomethane, more commonly referred to today as RNG, is the target product for inclusion in the natural gas pipeline grid.

If concentrated and compressed, and ideal application of biogas exists in vehicle transportation. Biogas powers automobiles. As early as 2007, an estimated 12,000 vehicles were being fueled with upgraded biogas worldwide, mostly in Europe. The big advantage for transport use can be that a fleet of trucks can be fueled by biogas very efficiently, if the vehicles are fueled at the same location as the biogas plant. If so, there is no cost for transporting the biogas to the point-of-use.