Introduction to Bioenergy

Transcription

1 1 Introduction to Bioenergy

2 1. Global Warming and Carbon Cycle

3 Carbon Cycle Carbon cycle Carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that are key to making the Earth capable of sustaining life: it describes the movement of carbon as it is recycled and reused throughout the biosphere. The global carbon budget is the balance of the exchanges of carbon between the carbon reservoirs or between one specific loop of the carbon cycle.

4 Carbon Cycle Carbon cycle An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir in functioning as a source or sink for carbon dioxide. Carbon-based molecules are crucial for life on earth, as it is the main component of biological compounds. Carbon is also a major component of many minerals. Carbon also exists in various forms in the atmosphere. Carbon dioxide is partly responsible for the greenhouse effect and is the most important human-contributed GHG. In the past two centuries, human activities have seriously altered the global carbon cycle, most significantly in the atmosphere.

5 Global warming Global warming: Causes and effects Earth s temperature has resin about 1 degree Fahrenheit in the last century. The past 50 years of warming has been attributed to human activity. GHGs are emissions that rise into the atmosphere and trap the sun s energy, keeping heat from escaping. During the past 100 years global sea levels have risen 4-8 inches. Damaging storms, droughts and related weather phenomena cause an increase in economic and health problems. Warmer weather provides breeding grounds from insects such as malaria-carrying mosquitoes.

6 Global warming Global warming: Causes and effects Burning fuels such as coal, natural gas and oil produce GHGs in excessive amounts. Most of the world s emissions are attributed to the large-scale use of fuels in vehicles and factories. Some predictions for local changes include increasingly hot summers and intense thunderstorms. The US was responsible for 20% of the global GHGs emitted in 1997.

7 Carbon cycle & biofuels

8 Biofuels & biorefinery

9 Conversion of biomass Thermochemical conversion - Pyrolysis - Gasification - Liquefaction Biological conversion - Bioethanol - Biogas Chemical conversion - Chemicals

10 2. Biomass and Bioenergy

11 Individual energy consumption

12 Population, food and energy

13 Population vs. Energy

14 U.S. energy consumption by source

15 New & Renewable energy New & Renewable energy Biomass Solar energy Geothermal energy Wind velocity Wave power Tidal power Ocean thermal energy (Nuclear energy) - Electric power - Solid, gas, liquid fuels, and chemicals Electric power

16 Biomass Biomass? Biomass is organic material made from plants and animals. Biomass contains stored energy from the sun. Plants absorb the sun's energy in a process called photosynthesis. The chemical energy in plants gets passed on to animals and people that eat them. Biomass is a renewable energy source because we can always grow more trees and crops, and waste will always exist. Some examples of biomass fuels are wood, crops, manure, and some garbage.

17 Types and sources of biomass

18 Biomass fuels When burned, the chemical energy in biomass is released as heat. If you have a fireplace, the wood you burn in it is a biomass fuel. Wood waste or garbage can be burned to produce steam for making electricity, or to provide heat to industries and homes. Burning biomass is not the only way to release its energy. Biomass can be converted to other usable forms of energy like methane gas or transportation fuels like ethanol and biodiesel. Methane gas is the main ingredient of natural gas. Smelly stuff, like rotting garbage, and agricultural and human waste, release methane gas - also called "landfill gas" or "biogas."

19 Biomass fuels Crops like corn and sugar cane can be fermented to produce the transportation fuel, ethanol. Biodiesel, another transportation fuel, can be produced from left-over food products like vegetable oils and animal fats. Biomass fuels provide about 3 percent of the energy used in the United States. People are trying to develop ways to burn more biomass and less fossil fuels. Using biomass for energy can cut back on waste and support agricultural products. Biomass fuels also have a number of environmental benefits.

20 3. Photosynthesis

21 Biomass & Photosynthesis

22 Classification of biomass for biofuels Woody plants Biomass Herbaceous plants Water plants Algae Microalgae Agricultural & Forest products wastes

23 Characteristics of biomass resources Advantages Renewable and sustainable resources Environmentally friendly clean energy resources Carbon neutral Uniform distribution worldwide Multipurpose resources and easy utilization Disadvantages High gathering cost (huge distribution area & volume) Pretreatment needed in its utilization Low energy level Variable production yield according to the environments