Industrial Application

Hi, welcome back. We just realized that we didn't update on the status of Greg and Lisa last week. Opps, sorry. Well, that happened because we were anticipating the appearance of Greg and Lisa's child (if you recalled the previous photo two weeks ago where Greg and Lisa were mating......).

Anyhow, we're still waiting........still waiting............

So, while doing so, why not let us show you how we created the terrarium for observation of Greg, Lisa, and their family members possible.

Step 1: Prepare a plastic aquarium. We used a 65 x 80 x 115 mm aquarium. Fill it with garden soil about one quarter of the aquarium, and not to forget, leaves. Greg and his families need them.

Step 2 : Invite the beetles into the temporary shelter.

Step 3: Make sure the beetles have food and water. There's plenty of leaves for them to chew on and we check on the soil to ensure the moisture is sufficient and water droplets are available for them.

Here's a video showing how Greg and his families and friends roaming around in the terrarium prepared specially for them.

Step 4 : Bring them out for some fresh air and keep them outside in the backyard where they were originally found.

Step 5 : Release them once observations are done. Yes, we will set them free at the end. After all, they belong to the nature.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

That's for the update, now back to business.

This week, we will propose a design for biogas generator specially tailored for residential use. This was inspired from the beetles as well as some industry applications. 

Buckle up as you ride through this long post. We will first introduce on the technology and usage of biomass before moving to the proposed design. 
To make things bearable, we will now reduce the font size........

As specified in our previous posts, different inspirations can be obtained from various types of beetles. One of these is the generation of biogas from beetles which have multiple uses in various industries. 

The bugs produce methane gas by that is generated through an anaerobic digestion process. This process involves the bugs to be oxygen deprived and as such they will break down biodegradable material to produce methane. After the biogas goes the removal of carbon dioxide or “biogas upgrading”, it can be used to run the “Bio-bug” Volkswagen vehicle.

What is biomass?

• Biological material obtained from living and recently living animals and plants.
• Carbon based and is made up of a mixture of organic molecules such as hydrogen, atoms of oxygen, nitrogen and small quantities of other atoms such as alkali, alkaline earth and heavy metals.
• Construction occurs by plant life absorption of carbon dioxide using energy from the sun.
• Plant materials are broken down and released carbon into the atmosphere, with carbon dioxide (CO₂) and methane (CH₄) mainly as the gases depending on the processes and conditions involved.

A wide range of materials are used in the biomass for energy. The largest biomass energy source is wood such as forest residue, yard clippings, wood chips and municipal solid waste. Other types of material include high yield energy crops, agriculture residues, food waste and industrial waste. Industrial biomass may be constructed from a wide variety of plants such as willow, sugarcane and bamboo as well as some tree species like eucalyptus and palm oil.

Biomass may be converted into methane gas and transportation fuels such as ethanol and biodiesel. These conversion processes can be classified into three different methods, namely thermal, chemical and biochemical.

Thermal conversion method of biomass

This process uses heat as its main basis to convert biomass into a chemical of another form. The types of combustion (gasification and pyrolysis) can be distinguished based on the amount of chemical reactions that occur. The main factors which dictate this are the oxygen availability and conversion temperature. This type of conversion is mostly suited for tropical countries since fuel wood needed for burning is more readily available. 

Direct combustion occurs if oxygen is actively present. Steam is produced by furnaces and boilers to help district heating and cooling system function or to drive turbines to produce electricity. In furnaces, biomass is converted to heat by burning in a combustion chamber. This heat is released in the form of hot air or water. In boilers heat of conversion may be converted into steam. Steam is then used to produce both electrical and mechanical energy, as well as for heating and cooling. 60-85% of energy in biomass fuel is present in a boiler’s steam.

Pyrolysis does not produce useful energy directly, yet it is able to convert biomass feedstocks into gas, oil or charcoal if the temperature and oxygen conditions are controlled. Since these energy products are denser than the original biomass, the cost of transport is reduced and they are able to be easily used in internal combustion engines and gas turbines since they possess more predictable and convenient combustion characteristics.

Gasification is a process in a which high temperatures and a controlled environment are used to  convert all the biomass into gas. Firstly, the biomass is partially combusted to produce gas and charcoal. Next, chemical reduction occurs. The gasifier separates these two stages and it works on temperatures of 800°C. Gasification is mainly used in power generation and in homes for cooking and lighting.

Chemical conversion method of biomass

The chemical conversion of biomass revolves around the chemical reactions that transform biomass into other types of useable energy. The most common type of chemical based conversion is known as transesterification. This conversion involves a chemical reaction through which alcohol binds itself with fatty acids from fats, oils and greases. During this process the viscosity of the fatty acids are reduced, therefore making them combustible. Biodiesel, glycerin and soap are the end products of transesterification. 

Image Source: http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.

Biochemical conversion method of biomass

Biochemical conversions involve the use of enzymes, bacteria and other microorganisms to turn biomass into liquid fuel. The two most important methods of biochemical conversion are anaerobic digestion and fermentation.

Anaerobic digestion involves the usage of microorganisms to break down organic material in environments lacking in oxygen. Anaerobic digestion of crop residues, food scraps and manure produce methane and carbon biogas. Anaerobic digestion starts with carbohydrates being broken down in hydrolysis. Hydrolysis is a chemical process water and a salt or weak acid is used to split molecules into parts. Next, the resulting amino acids and sugars are converted into carbon dioxide, ammonia and organic acids. Lastly, these products are converted into methane and carbon dioxide by the remaining bacteria. Under the right temperatures (between 0°C and 60°C), the bacteria are able to convert 90% of the biomass feedstock into biogas. The leftovers of the biomass may be used as fertilizer , animal bedding or low-grade building products such as fiberboard.

Fermentation uses yeast in the conversion of carbohydrates to ethanol and bioethanol. Firstly, a slurry is formed by grounding and combining crop materials with water. After that, the heat of the slurry is increased and enzymes are added to break down the ground materials while converting starch into glucose sugar and producing a more refined slurry. Yeasts are then added to the sugary slurry and they are both pumped into a fermentation chamber. Finally, after about 48-50 hours, alcohol is divided from the left over materials by distillation of the fermented liquid.

The application of biogas is not solely confined to the green car industry. Biogas is also used in the heating appliances industry. Biogas does not require any pre-treatment other than water removal for heating purposes. It can be used to heat buildings in conjuction with a biogas plant and district heating power production.

Biogas is also a major contributor to the electricity generation industry. A gas powered generator is able to produce heat and electricity. The design of the plant decides the amount of heat and electricity generated, with the percentages being 35% electricity and 65% heat respectively.

Image Source: http://formligdesign.se/project/illustration-vireo-energy-2/

The following section describes anaerobic process which converts organic wastes into biogas, turning these wastes into useful resource for us.

Anaerobic Digestion

Anaerobic digestion is a series of processes that breakdown biodegradable material into simpler forms of chemical compounds (digestion) in the absence of oxygen (anaerobic). There are four main processes in anaerobic digestion: 

1. Hydrolysis: Complex organic matters such as carbohydrates, proteins and fats broke down into soluble forms using water. 
2. Fermentation/ Acidification: Convert soluble molecules into acids by adding in acidogenic bacteria. Amino acids obtained from proteins gave sustainable amount of energy in the form of adenosine triphosphate (ATP) to breakdown organic matters in the process. In general, most sugars are converted directly into acetic acid.
   
   C₆H₁₂O₆ à 3 CH₃COOH
   
   Besides acetic acids, many other organic acids, alcohols, aldehydes, carbon dioxide, and hydrogen were formed from those organic matters. These products formed differently depending on the hydrogen concentration during fermentation process. In the formation of biogas, acetic acid, carbon dioxide and hydrogen gas are the most important product.
3. Acetogenesis: To fully utilise the resources to form biogas, the other acids formed from fermentation process will pass through acetogenesis process to convert those acids to acetic acid and hydrogen. This process uses acetate bacteria such as Syntrophomonas  and Syntrophobacter.
4. Methanogenesis: The final phase of anaerobic digestion is the production of methane gas which is the essential product for biogas. Methane gas can be formed via two ways using methanogenic bacteria.
   
   CH₃COOH à CH₄ + CO₂              CO₂ + 4 H₂ à CH₄ + 2 H₂O
   
   In the first chemical equation, acetic acid forms into methane and carbon dioxide. The carbon dioxide is reused along with hydrogen gas to form more methane gas and water as the by-product as depicted in the second chemical equation.

For more detail on anaerobic digestion, please refer to the journal titled 'Methane fermentation process as anaerobic digestion of biomass: Transformations, stages and microorganisms' by Ziemiński and Frąc.

The production of biogas through this process is used as the main source of power for the "Bio-bug". Biogas can be used to produce electricity as well with a biogas engine and generator.

In the following sections, we will further look into how biogas engine and generator work. 


What is a Gas Engine?

• An internal combustion engine which runs on a gas fuel such as coal gas, producer gas, biogas, landfill gas, or natural gas.
• Also known as gaseous-fueled engine, natural gas engine, or spark ignited. 
• Normally used for heavy-duty industrial engine.
• Can run continuously at full load for periods of 8760 hours per year, compared to gasoline automobile engine which runs for no more than 4000 hours in its working life. 
• Typical power ranges from 10 kW to 4000 kW.

How does a Gas Engine Works?

Gas engine actually uses the same working principles as any other internal combustion engine but using gaseous fuels such as biogas to produce electricity instead of the conventional gasoline. 

A gas engine applies venturi system to allow gas into the air flow. 

In brief, the total process consists of :

• Several digesters that produce biogas with biogas flowmeter attached to it. 
• The biogas is transferred into a low pressure gas holder, to act as a buffer in the system. 
• Four flares of gas occur once the low pressure gas holder achieved its upper limit. 
• Four gas blowers are used to increase the biogas pressure from 2.5 kPa to 45 kPa. This is to ensure optimum engine performance. 
• Gas is transmitted through pipe lines across the plant to be consumed by the engines. 
• Two engines are set up which can operate on natural gas or biogas. These are the primary engines for controlling. 
• All the engines have flowmeter for biogas and natural gas consumption flow measurements. 

What are the applications of gas engine?

There are generally two main applications of gas engine, which are the stationary and transport applications.  

Stationary Engine

Image source: https://www.clarke-energy.com/wp-content/uploads/Gas-engine-basic-components.png

Biogas engines are generally used for power production in industries where there are access to abundant of organic waste. For instance, the animal farms and large factories that produce significant amount of human, animal, and plant wastes. 

Stationary engines are used for baseload power, that combines heat and power for power supply plant. Some of the companies manufacture gas engines include GE Jenbacher, Caterpillar Inc., Cummins, Kawasaki Heavy Industries, and more. 

The popularity of biogas engine is mainly due to its ability to reutilize the unwanted organic waste to useful biological gaseous fuels. 

It is important to understand the energy content of the fuel gas, in this case the biogas in order to analyse on its power efficiency. In summary, the conversion efficiency of a combined heat and power plant can be defined as :

Efficiency of combined heat and power plant = (Electrical out put from an alternator + Themal output from gas engine ) ÷  Energy input to gas engine based on lower heating value (LHV) of the gas  x 100 

Gas engine energy balance.
Image source: https://www.clarke-energy.com/wp-content/uploads/Gas-engine-energy-balance.png

The LHV of a fuel is the amount of heat from a fuel after the latent heat of vaporisation. It determines the fuel flow required to go into the gas engine. Fuel LHV is normally stated in units of kWh/Nm³ .

Transport Engine

How about transportation engines? Compressed natural gas (CNG) engines is growing in the bus sector. Some of the users for such engine include Reading Buses. Here's some descriptions of the component involved (Misra Auto Gas - Leader in CNG - Gujarat, 2015)(Freepatentsonline.com, 2015). 

Compressed Natural Gas (CNG) engine components.
(Image source:http://www.actionalternativefuels.com/howdoescngwork.html)

CNG Components	Functions
CNG cylinder	A Storage tank for natural gases (methane)
Cylinder Value	A valve to manual closing/opening of gas flow
Injector Emulator	A control system which can stop either petrol or gas supply, when the driver using LPG/CNG, the Emulator shut off the petrol injector, stop petrol supply, meanwhile, it provides injector simulated signals and oxygen sensor simulated signals to OEM ECU, to facilitate it works as normal, or When using petrol, the Emulator wires to petrol injectors and O2 sensor are all under connection, no influence to original car ECU's normal function
Timing Advance Processor	TAP is the chip that used for advance an engine timing mainly to avoid back firing and to increase the engine pick up.
Gas-Air Mixer	A device that ensure the air-fuel mixing to its correct proportions.
Pressure Gauge	Device for measuring the pressure of the CNG.
CNG Reducer	Device that supplies sufficient gases to the engine.
Stepper Motor	A stepper-motor gas valve control is disclosed that includes a main diaphragm in a chamber that controllably displaces a valve relative to an opening in response to changes in pressure, to adjust fuel flow through the valve.
Filler Valve	A Valve to supplies gas to the CNG cylinder.
Changeover Switch	A switch to switch shut the petrol motor & convert car on gas.
Lambda Feedback System	A control system that give sufficient gas to engine by pressure & increases car pickup.

Why Biogas?

Let's take the case of dung beetle. 

Dung beetles have important role in the ecosystem and to the human society. They bury and consume dungs which then improve the soil structure and support nutrient recycling. 

Besides, removing animal faeces prevent pests at the cattle habitat. This in turn protect the livestock by reducing the population of pestilent bush flies. 

Equally important is the standards of hygience. In U.S. cattle industry, USD 390 million are saved just by having dung beetles to remove the animal manures. Emissions of nitrous oxide (a greenhouse gas) can also be reduced from agriculture. 

Similarly, biogas is inspired from the ability of bugs such as dung beetles which fully utilized the potential of animal wastes. Here are some of the advantages and disadvantages of the application of biogas. 

Advantages	Disadvantages
Renewable source of energy Biogas is created mainly by waste products and decays (Conserve-Energy-Future, 2013). Meets the energy demands of industry and replaces fossil resources	Lack of Technology Advancement Current systems used to create biogas are not very efficient  Not many investors.  Many researches are still going on
Environmental Friendly Biogas production does not require oxygen  Does not pollute the environment Uses waste materials in landfills and dump sites.  Reduces soil and water pollution	Impurities Contains a few impurities after the refining process The impurities may be corrosive to engines when it is used as fuel.  Sulphide and odor formation (Claassen et al., 1999).
Cheap Biogas can be used to produce electricity and heat Can be used as car fuels (Compressed Natural Gas) Production can be carried out in small plants or a large plant.	Not suitable for large scale Biogas production is not economically viable on a large scale. Difficult to increase the efficiency of biomass systems.
Reduce Greenhouse Effects Biogas is produced using the gasses in landfills as a form of energy. It recycles the biodegradable wastes.	Unstable Methane is flammable when it in contact with oxygen  Hence, it is prone to explosions.

Proposed Product

Here's a proposed design by us, inspired from the utilisation of biogas and convert it into usable energy. 

Project Title: Biogas Generator for Residential Use

Overview of Design Concept

The design uses a generator that is suitable as a replacement for the conventional natural gas tanks commonly found in residential areas for cooking purposes. This generator can be applied in communities near to farms where animal manures are easily available. Other than that, the generator can also be utilised in larger scale where the biogas sources will be from landfills and underground sewer pipes. In this study, the small-scale generator is described as follows.

This biological inspiration follows the way ecosystem works between animals and plants. 

Source: http://www.bbc.co.uk/staticarchive/e50a5444d22ff5e17097934e8c0a428b4c2a9629.gif

Design Illustration

Proposed sketch of biogas generator system.

Design of biogas generator system using CAD.

Material List

Item	Description	QTY	Unit
1	High-Density Polyethylene (HDPE) Tank	2	pcs
2	Vinyl Braided Tubing 1 in. x ¾ in.	5	ft
3	Pressure Safety Relief Valve SFA 15 T	1	pcs
4	Ball Valve, Brass PFFP600, 200PSI	2	pcs
5	T adapter Brass ½” female x ½” male x 3/8” male	1	pcs
6	Compression Nuts (for T Adapter)	3	pcs
7	Brass Inserts (for T Adapter)	3	pcs
8	Hose Barb Fitiing ¾ In, ½ In MNPT, Brass	2	pcs

The digester and gas holder size is dependent on the amount of waste added. The required digester volume (V_D) can be calculated through (Design, construction and maintenance of a biogas generator, n.d.) :

V_D = V_B x HRT

 where:

 V_D = Volume of the digester (m³)

 V_B = Volume of biomass added per day (m³ / day)

 HRT = Retention time required (days)

Similarly, the volume of the gas holder (V_G) is dependent on the relative rates of gas production and consumption. To calculate the daily gas production, the following equations can be used. An additional 20 % safety margin is recommended.

   G = V_B x G_{y (moist mass)}

G = LSU x G_{y (species)}

where:

G = Daily gas production rate (m³/ day)

M_B = Mass of biomass added per day (kg/day)

LSU = Number of live stock units (number)

G_{y (moist mass)} = Gas yield per kg of excrete per day (m³/kg/day)

G_{y (species)} = Gas yield per kg of live stock unit per day (m³/kg/day)

How it works?

The Biogas Collection System

Step 1: To prepare the manure mixture

1. Placing manure pellets into the digester bottle which is made of plastic.
2. Adding water to the level close to the top of the bottle.
3. Stirring the manure and water mixture to release trapped air bubbles. 

Step 2: To store the manure mixture

1. Lock the cap and ensure the ball valve is closed so that gas accumulated until it reached certain pressure before transferring to the biogas storage tank.
2. Set the biogas generator digester into a warm location such as sunlit window.

Step 3: The biogas storage tank

1. Use vinyl tubing, T-adapter, and ball valves to connect the digester and biogas storage tank.

2. Attach pressure valve to monitor on the level of biogas generated for safety purposes.

3. Close the ball valve connecting the biogas storage tank and tubing to the stove to allow biogas passing freely in the system without reaching to the stove.

Step 4: To utilize the biogas.

1. Open the ball valve to allow biogas flows towards the tubing connected to the stove.

2. Ball valve can be controlled to adjust the amount of biogas transferred. 

Reflection

1. Do you think the biogas generator would work if manufactured?

Biogas generator is a green technology which converts waste into useful energy that is used for heating and cooking. In India, there are many families living in the rural areas use dry cow manure in place of firewood to cook. Farmers usually dry the manure under the sun and shape it into cake-size for storage. Similar to the firewood, the manure can be easily burned and retains heat for a long period of time. This concept is identical to the biogas generator except that the fuel is stored in the form of methane gas instead of dry manure. Besides, it has been proven that biogas (usually methane gas) can be used as the fuel for combustion applications.

2. Do you think that you could raise funds to pay for manufacturing?

This generator has great marketing potential due to its cost-effectiveness. The system uses waste as the fuel to perform the same task as the conventional cooking gas in our house. We believe that this concept will attract many environmentalist knowing that the conventional natural gas is a limited resource whereas the cow manure is seen as wastage. The initial cost of installation might be expensive due to newness of the technology but this can be mitigated when the generator is being mass produced. Besides, the production of manure pallet for the generator opens a business opportunity for the farmers.


3. Do you think that many engineers explore solutions from nature into their inventions?

Energy has always been an issue to look into when it comes to sustainable developments. Various types of renewable energy sources are seek after to ensure there will be continuous supply of power for generations to come. Thus, biomimetics come into the picture for designing products and systems around the world. It is known that nature knows best and each design in nature is unique and useful in one way or another. There is an increasing amount of engineers search for inspiration from the nature. The previous post about the bioinspiration from beetles are just some of the examples for integrating nature into inventions. There are many other more for us to explore on. 

That's all for this week. Hope you enjoy reading it as much as we enjoy writing it. We'll see you again next week. *cheers*
Oh, and please share with us your thoughts and comments below. It's always fun to connect with our readers. 
Till then. :)

Reference:

Claassen, P., van Lier, J., Lopez Contreras, A., van Niel, E., Sijtsma, L., & Stams, A. et al. (1999). Utilisation of biomass for the supply of energy carriers. Applied Microbiology And Biotechnology, 52(6), 741-755. doi:10.1007/s002530051586

Conserve-Energy-Future,. (2013). Advantages and Disadvantages of Biogas - Conserve Energy Future. Retrieved 16 May 2015, from http://www.conserve-energy-future.com/advantages-and-disadvantages-of-biogas.php

Design, construction and maintenance of a biogas generator. (n.d.). 1st ed. Oxfam.

Freepatentsonline.com,. (2015). STEPPER MOTOR VALVE AND METHOD OF CONTROL - Santinanavat, Mike C.. Retrieved 15 May 2015, from http://www.freepatentsonline.com/y2010/0009303.html

Misra Auto Gas - Leader in CNG - Gujarat,. (2015). Function of CNG-LPG Kit Components. Retrieved 15 May 2015, from http://www.cngkitprices.in/function-cng-lpg-kit-components/

Ziemiński, K., Frąc, M. (2012). Methane Fermentation Process as Anaerobic Digestion of Biomass: Transformations, Stages and Microorganisms. African Journal of Biotechnology, 11(8), 4127-4139.