Chapter 4 Natural Resources. Natural resources (economically referred to as land or raw materials) occur naturally within environments that exist relatively

绿色化学电子教案


Chapter 4 Natural Resources Chapter 4 Natural Resources



Natural resources (economically referred to as land or

raw materials) occur naturally within environments that

exist relatively undisturbed by mankind, in a natural form.

A natural resource is often characterized by amounts of

biodiversity existent in various ecosystems. Natural

resources are derived from the environment. This is

currently restricted to the environment of Earth yet the

theoretical possibility remains of extracting them from

outside the planet, such as the asteroid belt. Many of

them are essential for our survival while others are used

for satisfying our wants. Natural resources may be further

classified in different ways.

5.1 Natural resources



On the basis of origin, resources may be divided into:Considering their stage of development, natural

resources may be referred to in the following ways: Biotic - Biotic resources are obtained from the

biosphere, such as forests and their products, animals, birds and their products, fish and other marine organisms. Mineral fuels such as coal and petroleum are also included in this category because they are formed from decayed organic matter.

Abiotic - Abiotic resources include non-living things. Examples include land, water, air and ores such as gold, iron, copper, silver etc.

Classification



Considering their stage of development, natural resources may be referred to in the following ways:Potential Resources - Potential resources are those that exist in a region and may be used in the future. For example, petroleum may exist in many parts of India, having sedimentary rocks but until the time it is actually drilled out and put into use, it remains a potential resource.Actual Resources are those that have been surveyed, their quantity and quality determined and are being used in present times. The development of an actual resource, such as wood processing depends upon the technology available and the cost involved. That part of the actual resource that can be developed profitably with available technology is called a reserve.



With respect to renewability, natural resources can be categorized as follows:Renewable resources are ones that can be replenished or reproduced easily. Some of them, like sunlight, air, wind, etc., are continuously available and their quantity is not affected by human consumption. Many renewable resources can be depleted by human use, but may also be replenished, thus maintaining a flow. Some of these, like agricultural crops, take a short time for renewal; others, like water, take a comparatively longer time, while still others, like forests, take even longer.Non-renewable resources are formed over very long geological periods. Minerals and fossil fuels are included in this category. Since their rate of formation is extremely slow, they cannot be replenished once they get depleted. Of these, the metallic minerals can be re-used by recycling them. But coal and petroleum cannot be recycled.



Some examples of natural resources include the following:Air, wind and atmosphere

Animals Coal, fossil fuels, rock and mineral resources

SoilsWater, oceans, lakes, groundwater and rivers



In recent years, the depletion of natural resources and attempts

to move to sustainable development has been a major focus of

development agencies. This is a particular concern in rainforest

regions, which hold most of the Earth's natural biodiversity -

irreplaceable genetic natural capital. Conservation of natural

resources is the major focus of natural capitalism,

environmentalism, the ecology movement, and green politics.

Some view this depletion as a major source of social unrest and

conflicts in developing nations.

Depletion



Mining, petroleum extraction, fishing, hunting, and forestry

are generally considered natural-resource industries.

Agriculture is considered a man-made resource. Theodore

Roosevelt, a well-known conservationist and former

United States president, was opposed to unregulated

natural resource extraction. The term is defined by the

United States Geological Survey as "The Nation's natural

resources include its minerals, energy, land, water, and

biota.



5.2 Energy resources and consumption

Despite advances in efficiency and sustainability, of all the

energy harnessed since the industrial revolution, more than

half has been consumed in the last two decades.However,

when considering this fact, it should not be overlooked that

this is primarily the result of global increases in the standard

of living and of the increase in world population, and not as a

failing of energy management as a whole.

Most of the world's energy resources are from the sun's rays

hitting earth. Some of that energy has been preserved as fossil

energy, some is directly or indirectly usable; for example, via

wind, hydro- or wave power.



Fossil fuels The twentieth century saw a rapid twentyfold increase in the use of fossil fuels. Between 1980 and 2006, the worldwide annual growth rate was 2%.According to the US Energy Information Administration's 2006 estimate, the estimated 471.8 EJ total consumption in 2004 was divided as follows, with fossil fuels supplying 86% of the world's energy:



Coal fueled the industrial revolution in the 18th and 19th century.

With the advent of the automobile, airplanes and the spreading

use of electricity, oil became the dominant fuel during the

twentieth century. The growth of oil as the largest fossil fuel was

further enabled by steadily dropping prices from 1920 until 1973.

From 2003 to 2008, coal, which is one of the dirtiest sources of energy, was the fastest growing fossil fuel..



Coal is the most abundant and burned fossil fuel. This was the

fuel that launched the industrial revolution and has continued to

grow in use; China, which already has many of the world's most

polluted cities, was in 2007 building about two coal fired power

plants every week. Coal is the fastest growing fossil fuel and its

large reserves would make it a popular candidate to meet the

energy demand of the global community, short of global

warming concerns and other pollutants.

Coal



According to the International Energy Agency the proven

reserves of coal are around 909 billion tonnes, which could

sustain the current production rate for 155 years, although at a

5% growth per annum this would be reduced to 45 years, or until

2051. With the Fischer-Tropsch process it is possible to make

liquid fuels such as diesel and jet fuel from coal. In the United

States, 49% of electricity generation comes from burning coal.



It is estimated that there may be 57 ZJ of oil reserves on Earth

(although estimates vary from a low of 8 ZJ, consisting of

currently proven and recoverable reserves, to a maximum of

110 ZJ) consisting of available, but not necessarily recoverable

reserves, and including optimistic estimates for unconventional

sources such as tar sands and oil shale. Current consensus

among the 18 recognized estimates of supply profiles is that the

peak of extraction will occur in 2020 at the rate of 93-million

barrels per day (mbd). Current oil consumption is at the rate of

0.18 ZJ per year (31.1 billion barrels) or 85-mbd.

Oil



There is growing concern that peak oil production may be reached in the near future, resulting in severe oil price increases. A 2005 French Economics, Industry and Finance Ministry report suggested a worst-case scenario that could occur as early as 2013. There are also theories that peak of the global oil production may occur in as little as 2–3 years. The ASPO predicts peak year to be in 2010. Some other theories present the view that it has already taken place in 2005. World crude oil production (including lease condensates) according to US EIA data decreased from a peak of 73.720 mbd in 2005 to 73.437 in 2006, 72.981 in 2007, and 73.697 in 2008. According to peak oil theory, increasing production will lead to a more rapid collapse of production in the future, while decreasing production will lead to a slower decrease, as the bell-shaped curve will be spread out over more years.



As of December 2009, the world had 436 reactors. Since

commercial nuclear energy began in the mid 1950s, 2008

was the first year that no new nuclear power plant was

connected to the grid, although two were connected in

2009.

Annual generation of nuclear power has been on a slight

downward trend since 2007, decreasing 1.8% in 2009 to

2558 TWh with nuclear power meeting 13–14% of the

world's electricity demand.

Nuclear power



The International Atomic Energy Agency estimates the

remaining uranium resources to be equal to 2500 ZJ. This

assumes the use of breeder reactors which are able to create

more fissile material than they consume. IPCC estimated

currently proved economically recoverable uranium deposits

for once-through fuel cycles reactors to be only 2 ZJ. The

ultimately recoverable uranium is estimated to be 17 ZJ for

once-through reactors and 1000 ZJ with reprocessing and fast

breeder reactors.

Nuclear fission



Resources and technology do not constrain the capacity of

nuclear power to contribute to meeting the energy demand for

the 21st century. However, political and environmental

concerns about nuclear safety and radioactive waste started to

limit the growth of this energy supply at the end of last

century, particularly due to a number of nuclear accidents.

Concerns about nuclear proliferation (especially with

plutonium produced by breeder reactors) mean that the

development of nuclear power by countries such as Iran and

Syria is being actively discouraged by the international

community.



Fusion power is the process driving the sun and other stars. It generates large quantities of heat by fusing the nuclei of hydrogen or helium isotopes, which may be derived from seawater. The heat can theoretically be harnessed to generate electricity. The temperatures and pressures needed to sustain fusion make it a very difficult process to control. Fusion is theoretically able to supply vast quantities of energy, with relatively little pollution. Although both the United States and the European Union, along with other countries, are supporting fusion research (such as investing in the ITER facility), according to one report, inadequate research has stalled progress in fusion research for the past 20 years.

Nuclear fusion





In 2008, renewable energy supplied around 19% of the

world's energy consumption. The renewables sector

has been growing significantly since the last years of

the 20th century, and in 2009 the total new investment

was estimated to have been 150 billion US dollars.

This resulted in an additional 80 GW of capacity

during the year.

Renewable energy



Renewable energy sources are even larger than the traditional

fossil fuels and in theory can easily supply the world's energy

needs. 89 PW of solar power falls on the planet's surface.

While it is not possible to capture all, or even most, of this

energy, capturing less than 0.02% would be enough to meet

the current energy needs. Barriers to further solar generation

include the high price of making solar cells and reliance on

weather patterns to generate electricity.

Solar energy



Current solar generation does not produce electricity at night,

which is a particular problem in high northern and southern

latitude countries; energy demand is highest in winter, while

availability of solar energy is lowest. This could be overcome

by buying power from countries closer to the equator during

winter months, and may also be addressed with technological

developments like Infrared Solar Panel systems which can

capture energy in cloudy conditions and even at night.

Globally, solar generation is the fastest growing source of

energy, seeing an annual average growth of 35% over the past

few years. Japan, Europe, China, U.S. and India are the major

growing investors in solar energy.



The available wind energy estimates range from 300 TW to

870 TW. Using the lower estimate, just 5% of the available

wind energy would supply the current worldwide energy needs.

Most of this wind energy is available over the open ocean. The

oceans cover 71% of the planet and wind tends to blow more

strongly over open water because there are fewer obstructions.

Wind power



At the end of 2005, 0.3 GW of electricity was produced by tidal power. Due to the tidal forces created by the Moon (68%) and the Sun (32%), and the Earth's relative rotation with respect to Moon and Sun, there are fluctuating tides. These tidal fluctuations result in dissipation at an average rate of about 3.7 TW.

Another physical limitation is the energy available in the tidal fluctuations of the oceans, which is about 0.6 EJ. Therefore, this limits the available tidal energy to around 0.8 TW (20% of the dissipation rate) in order not to disturb the tidal dynamics too much. Waves are derived from wind, which is in turn derived from solar energy, and at each conversion there is a drop of about two orders of magnitude in available energy. The total power of waves that wash against our shores add up to 3 TW.

Wave and tidal power



Waves are derived from wind,

which is in turn derived from

solar energy, and at each

conversion there is a drop of

about two orders of magnitude in

available energy. The total power

of waves that wash against our

shores add up to 3 TW.



Worldwide hydroelectricity installed capacity reached 816 GW in 2005, consisting of 750 GW of large plants, and 66 GW of small hydro installations. Large hydro capacity totaling 10.9 GW was added by China, Brazil, and India during the year, but there was a much faster growth (8%) small hydro, with 5 GW added, mostly in China where some 58% of the world's small hydro plants are now located. China is the largest hydropower producer in the world, and continues to add capacity. In the Western world, although Canada is the largest producer of hydroelectricity in the world, the construction of large hydro plants has stagnated due to environmental concerns. The trend in both Canada and the United States has been to micro hydro because it has negligible environmental impacts and opens up many more locations for power generation.

Hydropower



Until the beginning of the nineteenth century biomass was the predominant fuel, today it has only a small share of the overall energy supply. Electricity produced from biomass sources was estimated at 44 GW for 2005. Biomass electricity generation increased by over 100% in Germany, Hungary, the Netherlands, Poland, and Spain. A further 220 GW was used for heating (in 2004), bringing the total energy consumed from biomass to around 264 GW. The use of biomass fires for cooking is excluded. World production of bioethanol increased by 8% in 2005 to reach 33 billion litres (8.72 billion US gallons), with most of the increase in the United States, bringing it level to the levels of consumption in Brazil. Biodiesel increased by 85% to 3.9 billion litres (1.03 billion US gallons), making it the fastest growing renewable energy source in 2005. Over 50% is produced in Germany.

Biomass and biofuels



Geothermal energy is used commercially in over 70

countries.In the year 2004, 200 PJ (57 TWh) of electricity

was generated from geothermal resources, and an additional

270 PJ of geothermal energy was used directly, mostly for

space heating. In 2007, the world had a global capacity for

10 GW of electricity generation and an additional 28 GW of

direct heating, including extraction by geothermal heat

pumps. Heat pumps are small and widely distributed, so

estimates of their total capacity are uncertain and range up to

100 GW.

Geothermal

Documents

Chapter 4 Natural Resources. Natural resources (economically referred to as land or raw materials) occur naturally within environments that exist relatively