Introduction to

Bioenergy

1

1. Global Warming and Carbon Cycle

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.

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.

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.

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.

Carbon cycle & biofuels

Biofuels & biorefinery

• Thermochemical conversion

- Pyrolysis

- Gasification

- Liquefaction

• Biological conversion

- Bioethanol

- Biogas

• Chemical conversion

- Chemicals

Conversion of biomass

2. Biomass and Bioenergy

Individual energy consumption

Population, food and energy

Population vs. Energy

U.S. energy consumption by source

Biomass

Solar energy

Geothermal energy

Wind velocity

Wave power

Tidal power

Ocean thermal energy

(Nuclear energy)

New & Renewable

energy

Electric power

- Electric power - Solid, gas, liquid fuels, and chemicals

New & Renewable energy

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.

Types and sources of biomass

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."

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.

3. Photosynthesis

Biomass & Photosynthesis

Classification of biomass for biofuels

Woody plants

Herbaceous plants

Water plants

Algae

Microalgae

Agricultural & Forest products wastes

Biomass

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