Tutor HuntResources Engineering Resources

Design Cycle For Biogas Technology

Date : 08/11/2016

Author Information

Gholamhossein

Uploaded by : Gholamhossein
Uploaded on : 08/11/2016
Subject : Engineering

Bangladesh lies in the southeast part of Asia. Bangladesh as a country is known to be one of the largest exporters of agricultural goods and to have a large number of fertile lands. However, most of these lands are not properly utilized due to lack to electricity. Electricity is required for processes of farming such as irrigation, fertilization or harvesting. This problem arises as 26% of the population lives under a dollar a day and only 62% of the population has access to electricity with an availability of 321 kWh per capita per annum.

Therefore, if we could provide the residences of the village in Bangladesh with a renewable source of energy, electricity can be produced leading the Bangladeshis to use their rich and fertile lands. This will reduce the percentage of people living in poverty, increasing the standing of living, improving the infrastructures and reducing the crime rates.

Not only will this solution improve the standards of living, providing cheaper options of producing electricity will also lower their costs of production which in turn will increase the total production of agricultural goods, which is their main source of exports. This will increase Bangladesh s exports while keeping their imports constant improving their current account in the balance of payments.

Conceive

As energy is a necessity and is vital for survival, us humans have gone through dire straits and have done whatever it takes to get access to it. This includes destroying our very own earth. Energy has been extracted from several sources in the past such as from fossil fuels. However, we have reached a time where the environment is in large concern. Therefore, alternate sources of energy which have less implications to the environment have been introduced.

It would be a dream come true if, we, Vitamin M, could convert something we consider redundant into something as essential as energy. A growing problem for our entire planet is waste and more importantly, what to do with it.

As years go by, our population is known to be increasing exponentially. With that, our daily consumption, waste, and demand for electricity and energy is also increasing at a similar rate.

A method to tie all of those concerns together is through the process of producing energy from biomass using Biogas technology. This technology enables us to recycle waste more efficiently, and also to generate more energy for the future. Not only is Biogas technology efficient and does not harm the environment, but it is also appropriate, affordable and culturally acceptable in the villages of Bangladesh. The biomass needed for the biogas technology to produce energy will simply be extracted from wood and general waste, such as animal or infrastructural residues. This creates an essentially constant infinite supply in energy, while also using an environmentally friendly alternative.

As in Bangladesh, this Bio gas technology can be replicated to be used around the world. With this technology, we can make a cleaner, greener, healthier and technologically advanced world a reality.

Brief

Our solution to creating a renewable source of energy for a remote village in Bangladesh is the processing of Biomass to Bio fuels. There are certain specifications and constraints that our design must follow.

As mentioned above, the solution is meant to create a renewable source of energy for a remote village. Therefore, one of our most important constraints is the retail price (cost) of the design. It must be made affordable for the residents of the village. The GDP per capita of Bangladesh is $ 957.8, meaning that the cost must be below this for each family.

The Biofuel design must be able to produce at least 321 kWh of energy per capita for most if not all of the residences. This is because the per capita energy at the current moment is already 321 kWh but only available to 62% of the residences. Our vision is to increase this number to at least 80%.

Biomass energy generally has a power (CHP) efficiency of approximately 75 to 80%. It is vital that our design strives for the highest efficiency rate possible, although a value in that range is more than satisfactory.

The energy produced from the biomass must be able to be transported about a 1 km radius as the village itself has an area of approximately 30 km2. It is extremely irrational to provide our design for each and every family as not only is it doubtful that each and every family will be able to afford it, but creating thousands of our design will undoubtedly affect us as well.

The Biogas technology must be a stable source of energy through both day and night such that no small external forces (storms, etc.) will be able to reduce or completely stop the production.

Details and Choices of Renewable or Future Fuel

Details and choice

Initially, there were several choices in which our group was interested in. These included solar energy, tidal energy, wind energy and biomass.

Solar, tidal and wind energy all had similar drawbacks in that the energy produced cannot be provided in an infinite constant manner. For example, solar energy is only available when there is a substantial amount of sunlight, i.e., day time when it s not raining, while wind energy is available when there is a substantial amount of wind. However, for biogas technology, there is always a certain amount of waste and thus also energy.

Biogas technology is feasible from three different aspects: technical, economical, and social.

Technical

Initially, sources of biomass like animal and industrial residues are gathered. They are then mixed with water and are heated as the preparation process in order to increase the contact between the biomass and the bacteria. The waste is then mixed with enzymes (macromolecular biological catalyst which can increase the efficiency of bacteria) in a reactor in order to speed up the process. The bacteria of the biomass thrive under controlled temperatures (around 100-200 degrees Celsius by electric heater powered by solar panels) which ensures the effectiveness of the enzyme. During the process, methane is being continuously collected from the reactor. After completing the process, the bio liquid (substance in the reactor) can be distillated to extract the biogas. The biogas may also contain CO2 (29%), H2S(1%), CH4(70%). CH4 is our useful product, also known as methane and natural gas. Methane can be refined by being collected from the top. If methane with high concentration are required, it can be further refined by reacting with hydrogen (CO2+2H2=CH4+O2).

The other gases are recycled and the methane is taken out from the process and fed into a compressor. The compressor compresses the methane to increase the pressure, also known as CNG (Compressed Natural Gas) so that it can be fed into a internal combustion engine. The high pressure is required as natural gas to does not easily combust at low pressures.

The process of an internal combustion engine run by CNG is similar to an internal combustion engine run by gasoline, only difference being CNG is mixed with oxygen from air in the carburetor instead of gasoline. Now this engine powered by renewable fuel is used for irrigation to help farming in remote locations.l

Waste collection can be easily done by humans and pipe system. The heat needed in the preparation can be achieved by electric heater powered by solar energy. The temperature required is relatively easy to reach and zero pollution or waste by solar. Temperature controlling in the reactor is harder, computed mechanism will be needed, but is still feasible. Building the reactor and distillation chamber are technically easy but they will cost a lot. Some of the biogas can be gained are directly collected from the reactor. Therefore, the scale of the distillation process is actually small.

Methane takes 70 percent of the biogas, but CO2 is a lot denser, so methane can be refined by being collected from the top. And afire that, the percentage will be more than 90.

Economical

Only a few things are perhaps less affordable by the residences: the reactor, the distillation chamber, compressor for the methane and solar panels.

However, this will be providing energy for the entire village and thus is worth when the cost is averaged out for each residence.

In the long run, after the crude oil and coal recourses are exhausted, the supply will increase rapidly, reducing costs to the villagers.

Social desirability

It is socially desirable as mentioned in the introduction due to its lack of consequences to the environment. Water only takes less than 1%, making it even more environmentally friendly. As mentioned above, the cost will definitely drop in the future as other non-renewable energy sources like fossil fuels are expended.

This resource was uploaded by: Gholamhossein