Bioenergy- Introduction.pptx

energy engineering

1. BIOENERGY

2. WORLD ENERGY CONTEXT GHGs AND CLIMATE CHANGE CARBON CIRCLE ORIGIN OF BIOMASS

3. INTRODUCTION Biomass is  organic material that comes from plants and animals Biomass is considered a renewable source of energy because: There is no net carbon dioxide emissions Carbon dioxide released when biomass is used as a fuel is balanced by carbon dioxide captured when the biomass is grown Bioenergy is renewable energy derived from recently living biological material , or biomass . Bioenergy is a form of renewable energy because: the energy contained in biomass is energy from the sun captured through natural processes of photosynthesis , and so long as the quantity of biomass used is equal to or less than the amount that can be regrown it is potentially renewable indefinitely .

4. INTRODUCTION Bio power- is electricity generated from combustion of biomass . Biofuel is commonly used to refer to biomass-derived liquid fuels and gases most typically used in transportation Heat and steam, or a combination of both, may also be produced through combustion of biomass.

5. INTRODUCTION WORLD ENERGY CONTEXT

6. INTRODUCTION

7. INTRODUCTION Biomass resources are potentially the world's largest and most sustainable energy source. The annual bio-energy potential is about 2900 EJ, though only 270 EJ could be considered available on a sustainable basis and at competitive prices . The expected increase of biomass energy, particularly in its modern forms, could have a significant impact not only in the energy sector, but also in the drive to modernize agriculture , and on rural development. The share of biomass in the total final energy demand is betwe7% and 27%. Source : http://www.worldenergy.org/wec-geis

8. INTRODUCTION-GHGs

9. INTRODUCTION-GHS GASESS AND CLIMATE CHANGE Greenhouse gases (GHGs)-are gases in the atmosphere that absorb emit and absorb thermal radiation in a process known as Greenhouse effect Greenhouse effect- a mechanism by which solar radiation is captured and earth is warmed to an extent necessary for supporting life ( Natural Greenhouse Effect) Primary GHGs are: water vapor, carbon dioxide, methane, nitrous oxide and ozone These gases differ in their abundances in the atmosphere as well as their warming power. The science of global climate change indicates an overall warming trend for the earth as a whole in association with rising levels of GHGs. (Global Warming) While natural sources contribute to GHGs and changes in their concentrations over time , global scientific consensus indicates that anthropogenic (i.e., human) sources of GHGs contribute to global climate change (Human Enhanced Greenhouse Effect) Human activity has enhanced the warming of the Earth

10. INTRODUCTION-GREENHUOSE EFFECT

11. INTRODUCTION-GREENHOUSE EFFECT

12. INTRODUCTION-GHGs In 2020 power plants were the biggest contributor to annual GHG emissions. Industrial process and transportation fuels were ranked second and third overall, respectively The contributions of power plants, industrial processes and transportation fuels to annual GHG emissions are a result of combustion of fossil fuels, most notably coal, natural gas and petroleum. These releases the carbon that was once stored in these non-renewable energy sources into the atmosphere as carbon dioxide and thereby enriches the greenhouse effect.

13. INTRODUCTION-THE CARBON CIRCLE Bioenergy has the potential to be carbon-neutral by balancing the amount of carbon released in use of bioenergy products with an equivalent amount put into and stored in soils, plant and animal tissues, or other material such as the ocean floor. That is, bioenergy is part of a global carbon cycle where plants take up atmospheric carbon dioxide and convert it into plant tissue (i.e., they sequester carbon). Carbon is released back to the atmosphere when the plant biomass is burned directly or after it has been converted into a fuel and used (i.e., carbon emissions), and from there it is available again for plant up-take (i.e., sequestration ). However , when taking a life-cycle assessment approach, bioenergy may or may not prove to be carbon neutral. The neutrality of bioenergy with regard to other GHGs such as methane and nitrous oxide is also questionable. Of importance in evaluating the carbon-neutrality of a bioenergy crop are land use change and feedstock production systems.

14. INTRODUCTION-THE CARBON CIRCLE

15. INTRODUCTION-CARBON CIRCLE AND BIOFUELS The carbon dioxide (CO 2 ) from the atmosphere is taken up by plants and converted into plant tissues. Plants are harvested and converted into fuels which are burned , releasing CO 2 into the atmosphere where it becomes available again for plants. However , instead of a “closed loop,” as depicted here, emissions of CO 2 from conversion of untilled soil and emissions from use of fossil fuels in fertilizer production and diesel use in farm equipment can increase the amount of atmospheric carbon dioxide from bioenergy systems rather reduce it.

16. INTRODUCTION-THE CARBON CIRCLE AND BIOFUELS The carbon dioxide (CO 2 ) emitted on combustion of biomass is taken up by new plant growth , resulting in zero net emissions of CO 2 . However , it should be remembered that there are some net CO 2 emissions associated with bioenergy when looked at on a life-cycle basis – emissions from fossil fuels used in the cultivation, harvesting and transport of the biomass. These are generally small compared to the CO 2 avoided by displacing fossil fuels with energy from biomass. Consequently , bioenergy is a renewable energy resource with the added benefit of being CO 2 neutral.

17. THE ORIGIN OF BIOMASS Biomass is biological organic matter derived from living or recently-living organisms Biomass encompasses a large variety of materials, including: - Grassy and woody plants - Residues from agriculture or forestry - Animal/human waste - Food crops - Organic component of municipal and industrial wastes Bioenergy is the renewable energy derived from recently living biological materials called biomass

18. BENEFITS OF BIOMASS Benefits of Biomass : Renewable energy, transportation fuels, and bio-based products Domestic source of energy Provides baseload electricity Healthy forests/reduce wildfire danger Turning a waste into a product Air quality benefits Greenhouse gas reduction Rural economic development Promoted by policy

19. INTRODUCTION-ORIGIN OF BIOMASS

20. ORIGIN OF BIOMASS Photosynthesis produces “carbohydrates” such as sugar, starch and cellulose from water and carbon dioxide. Efficiency of sunlight absorption/conversion during photosynthesis is 0.1-3%, but a fraction of it is lost in other products. Carbohydrates are also called saccharides. Carbohydrates in plants are sugars and polymers of sugar: starch, hemicellulose and cellulose . Sugars (oxygenated hydrocarbons) in fruit juices can be fermented (digested biologically) into alcohols. Starch is granular polysaccharide found in seed, tubers, roots and stem pith; corn, potato, rice, tapioca. Dry wood is 66% holocellulosic (combination of cellulosic and hemicellulsic ) and 25% lignin , and the rest is resins, gums, tannins and waxes. About 25% of the holocellulose is hemicellulose , the rest is cellulose and some lignin.

21. ORIGIN OF BIOMASS

22. THE ORIGIN OF BIOMAS Cellulose is made of fibrous polysaccharides, the main constituent of the plant cell wall which helps plants maintain their structure and form The cellulose fibrils are stabilized by hydrogen bonding among different strands, which also determines the crystalline or amorphous nature of cellulose such as cotton, wood , hemp and straw. They are insoluble and chemically inert, and resist acidic or enzymatic hydrolysis. Hemicellulose is made of polysaccharides, but they are more soluble than cellulose. It is amorphous, is dissolved by dilute alkaline solutions, and can be hydrolyzed to fermentable sugars . Lignin is not a carbohydrate. It is a polymer of single benzene rings linked with aliphatic chains (mostly phenolic compounds). Lignin is an important constituent of the walls of woody plants, providing the plant with glue and strength. It is amorphous and more soluble, but completely resists hydrolysis and is resistant to microbial degradation. It is removable by steaming or by

23. THE ORIGIN OF BIOMASS Lignocellulosic biomass (LB) is a common phrase used for all plant-based materials with the composition of cellulose, hemicellulose, lignin, proteins, and other phenolic components . General structure of LB present in biomass and its chemistry

24. THE ORIGIN OF BIOMASS

25. THE ORIGIN OF BIOMASS

26. Assignment-Presentation Explain the social, economic and environmental impacts of bioenergy