The Biogas Production Worldwide Environmental Sciences Essay

Energy is a necessary concomitant of human existence. Basically, there exist various sources of energy like coal and other petroleum products that are commercially exploited for many useful reasons. These fossil fuels have become a strong pillar of the economy and it has penetrated so deep in the mechanism of human living that it has become almost impossible to think of a world running without fossil fuel. Yet it is a fact that this source of energy will not last forever. Once, fossil fuels were available abundantly and at low prices. However, nowadays its price is high rocketing on the international market and it is also becoming very scarce. The immediate effect of this is that the world is facing the phenomena of inflation and rising prices. Moreover, today there is an energy crisis that has arisen due to the fear that the boons of fossil fuel may turn into a bane with its disappearance. In addition, the burning of fossil fuels releases carbon dioxide and other toxic gases in the atmosphere and a direct consequence of this is global warming.

1.1 Background

Energy and energy resources can be known to be the backbone for survival on earth. People are heavily dependent on various energy sources like coal or fossil fuels so as to meet up with their daily needs whether it is in the power sector, the transportation sector or for cooking and heating purposes and about 88% of this demand is met by fossil fuels (Peter Weiland, 2009). It is predicted that the use of fossil fossils will come close to surpassing oil consumption by 2017 (IEA, 2012). On the other hand, greenhouse gases (GHGs) emissions in the environment are also increasing rapidly, with carbon dioxide being the highest contributor. Another global energy challenge is the depletion of fossil fuels. Due to the increasing demand, the availability of the fuel is decreasing. In addition, conventional oil and gas reserves are mostly found in politically unstable countries, making its ease of use less accessible.

In this context, biogas can be derived from wastes, animal manure or energy crops so as to meet with the increasing energy demand in the future. Biogas can be defined as a versatile renewable energy source which can replace fossil fuels in the power and heat production sector and in the transportation sector. It has the capacity to replace natural gas also for producing chemicals and liquefied petroleum gas for cooking purposes.

Table .1: comparison of heat values and efficiency of commonly used fuels with biogas (Nabard, 2007)

Commonly used fuels

Calorific values in kilo calories

Thermal efficiency

Biogas

4713/M3

60%

Firewood

2093/kg

11%

Diesel

10550/kg

66%

Kerosene

10850/kg

50%

Petrol

11100/kg

–

Biogas production through anaerobic digestion (AD) process has many advantages over other bioenergy forms. It is one of the most energy- efficient and environmentally friendly bioenergy technologies. It not only reduces the emission of greenhouse gases drastically compared to fossil fuels, but it also produces high grade fertilizer as by- product.

1.1.1 Biogas production worldwide

In the field of biogas, Germany has built itself a world top leading position. In 2006, it built 826 biogas systems to a total increased production unit of 3700, hence making Germany the number one biogas- based energy producer (Energy solutions, 2012).

Figure .1: various substrates available in Germany having the potential energy accumulated for biogas production (Baltic Biogas Bus Project, 2012)

The world’s biogas market is predicted to reach $8.98 billion by the year 2017, with the desire to reduce dependency on fossil fuels and to focus on eco- friendliness biogas programs (GIA, 2012).

Latin America is also well known for its biogas technology in municipal raw sewage treatment and landfill gas technology. It has identified 25 types of wastes for biogas production. The country has 33 R&D projects and since 1977, five projects have already been implemented to produce biogas from sanitary landfills. Latin America produces around 217 million m3 per year which is mostly used for cooking, lighting, vehicle fuel and town gas. (H.Naveau, 1993)

Moreover, the biogas market has grown rapidly in the recent years for the cogeneration of heat and power and for the production of bio- methane to be used as vehicle fuel. In the European Union (EU), 17% of all the energy will have to be produced from renewable sources, and in the transport sector it has to reach 10% of the total according to the European Directive 2009/28/EC, thus making biogas the viable solution to reach this target.

The reasons for having a spread out on the biogas energy market includes an increase in demand for distributed generation, severe environmental rules arising due to lots of pollution and an accelerating increase in infrastructure and vehicle build out adapting with natural gas. According to Pike Research, this fast- growing market reached $17.3 billion in global revenue in 2011, and this will almost double by 2022 to an amount of $33.1 billion (Globe- Net, 2012).

biogas_640x383.jpg

Figure 1.: Biogas market value by regions (Pike Research, 2012)

1.1.2 Energy sector in Mauritius

Mauritius is an island having no oil, coal reserves or natural gas. It is heavily dependent on imported energy resources. The Ministry of Renewable Energy and Public Utilities (MPU) is responsible for the energy policy including energy, water and wastewater in the island. The Central Board of Electricity (CEB) occupies the generation, transmission, distribution and sale of electricity and the State Trading Corporation (STC) import petroleum products like gasoil, fuel oil and LPG.

With the increase in standard of living, industrialization, population growth and more development in the transportation sector, the energy demand is climbing at an exponential rate in Mauritius. We are becoming an energy dependant society and as per the graph below, the exportation of gas oil will be more than doubled by the year 2025.

Table 1.: Imports of energy sources in Mauritius in 2011 (Energy and water statistics, 2011)

Energy source

2011 (Ktoe)

Gasoline

126.0

Diesel oil

313.0

Kerosene

4.5

LPG

71.6

Coal

409.3

Figure1.3: Forecast of petroleumn product imports in Mauritius (Outline Energy Policy, 2007)

Moreover, with the depletion of the energy sources, the price of the fuel are augmenting, hence making it more difficult to afford. Hence, to avoid an energy crisis in the future, other forms of energy resources need to be exploited which is environmentally friendly and has an infinite reserve.

Figure 1.4: Trend in price of exported fuel from 2002 to 2011 (Energy and water statistics, 2011)

The figures above demonstrate how Mauritius depends greatly onto fossil fuels, and this trend is going to increase in the years to come. Hence, new alternatives need to be found so as to match with this increasing demand. However, the alternate options should be in line with the Maurice Ile Durable (MID) concept; a renewable and environmentally friendly source.

In each and every home in the Mauritian society, one makes use of LPG for cooking purposes. The actual price of the gas cylinder is Rs540. If the government maintains the price at Rs330 for consumers, the STC will have to look for Rs 820 million for subsidy. This is due to the increasing price of butane and propane in the global market. Hence, to remedy this, cooking gas can be obtained locally from anaerobic digestion of organic waste to produce biogas. It fits in the MID, whereby according to Pr de Rosnay, 37% of electricity will come from biomass/biogas by 2028.

1.2 Rationale

In Mauritius, we are already a fossil fuel dependant society. Hence, to reduce this problem of dependency on the already depleting resource, we can focus on the use of biogas at our home itself. Moreover, with the concept of the MID, we are adopting a renewable energy source, which in the course of time can expand to the production of electricity.

Also, we already have the problem of overfilling of our landfill at Mare- Chicose. Thus, by using our household organic waste, we not only produce useful cooking gas, but we also has as by- product a high grade fertilizer and we are alleviating the problem of our landfill.

In addition, by converting the gas into methane to be used for cooking purposes, large amounts of carbon dioxide are not emitted in the environment, thus protecting our planet from global warming. And also, we are discarding much of the waste from the surrounding into useful products.

Lastly, with the expansion of the biogas energy system in our country, more jobs can be created in the field of energy, whereby Mauritius can later be self- sufficient in the production of cooking gas and eventually in the production of electricity, thus reducing on imports.

1.3 Aims and Objectives

The aim of this project is to produce an improved biogas system that can be adopted in a household for cooking purposes along with implementing its safety processes. To achieve this, the objectives identified are:

To have an understanding of the functioning of the process to produce adequate biogas for cooking.

To improve the biogas system by modifying the previous set- up

To optimize the system by focusing on:

Design of the system

Ratio of substrate to be used

Conditions to consider to favor biogas production

To modify a cooking stove so as it can operate on biogas.

To make laboratory testing to determine the methane composition in the biogas and the heating value.

To study the risks and safety processes associated with the digester and to implement it.

To make an assessment of the amount of gas produced for cooking purposes

1.4 Structure of report

Chapter one- Introduction

This chapter introduces the project title and gives an overview of energy trend in Mauritius and worldwide and the aim and objectives of the project.

Chapter Two- Literature Review

The types of anaerobic digestion process to produce biogas and the factors affecting the process are discussed, along with the production of biogas in the island. Also, the safety and risks associated with the system are identified.

Chapter Three- Methodology

The methods undertaken to construct the reactor and analytical testing of the feed and product of the biogas system are considered.

Chapter Four- Design and Construction

The materials of construction and cost analysis are assessed.

Chapter Five- Results and Discussions

The economic analysis and findings from analytical tests are observed and discussed.

Chapter Six- Safety Implementation

The safety precautions that need to be applied to the biogas system are discussed.

Chapter Seven- Conclusion, Recommendation, Future works

A summary of the aims of the project is made and some recommendations and future work are mentioned for improvements.