Role of Organisms:
Organisms
can be either
producers or consumers in terms of energy flow through an
ecosystem.
Producers convert energy from the environment into carbon
bonds, such as those found in the sugar glucose. Plants are the most
obvious examples of
Producers; plants take energy from sunlight and use
it to convert carbon dioxide into glucose (or other sugars). Algae and
cyanobacteria are also photosynthetic producers, like plants. Other
producers
include bacteria living around deep-sea vents. These bacteria
take energy from chemicals coming from the Earth's interior and use it
to make sugars. Other bacteria living deep underground can also
produce sugars from such inorganic sources. Another word for producers
is autotrophs.
Consumers get their energy from the carbon bonds made by
the producers. Another word for a consumer is a heterotroph. In the
flow of energy and inorganic nutrients through the ecosystem, a few
generalizations can be made: 1. The ultimate source of energy (for most
ecosystems) is the sun. 2. The ultimate fate of energy in ecosystems is
for it to be lost as heat. 3. Energy and nutrients are passed from
organism to organism through the food chain as one organism eats
another. 4. Decomposers remove the last energy from the remains of
organisms. 5. Only inorganic nutrients are cycled, energy is not.
Consequences of excess energy consumption:
Burning of fossil fuels for industrial, commercial and domestic energy
use, as well as transportation, is the primary human source of
greenhouse gases. This causes the greenhouse effect, wherein a layer of
gases suspended in the atmosphere around the earth prevents the sun’s
rays being reflected from the earth’s surface back in to space. This
means that the warmth of these rays is trapped within the earth’s
atmosphere, creating a layer of insulation that maintains warmth enough
for plants, animals and people to exist. Greenhouse Gases (GHGs)
enhance the heat retaining ability of this insulating layer, and hence
the average temperature on earth increases. Extreme weather events like
drought, torrential rain, hurricanes, floods, typhoons, monsoons and
forest fires are due to changing weather patterns brought about by global warming.
Excessive biomass burning causes domestic air pollution, which affects
the general health of the population. Water pollution affects marine
organisms and indirectly, humans.Human activity needs to adapt
to these conditions –which impact economic activity, food security,
rural and urban settlements, and freshwater supply. This shift also
affects biodiversity.Many species adapt to long term temperature
changes very gradually, and as such will be unable to adapt to more
rapid changes in climate conditions. There may be a number of
unpredictable feedback effects to natural systems, such as the
irreversible loss of key habitats and cities.
To create a
sustainable energy culture, two action areas are advocated:
1. Increased
energy efficiency: including efficient production and consumption and
use of cleaner fossil fuel technology.
2.
Diversification of the energy mix: The use of alternative fuels
(emitting low or no CO2) is growing . Initially these will help reduce
reliance on fossil fuels and eventually allow for cessation of all
fossil fuel combustion. These include:Substitution: Use of natural
gas is growing. This is relatively cleaner than coal or oil, and is
seen as an interim alternative until new technologies are more readily
available.
Fuel Cell Technology: Hydrogen is thought to be the
fuel of the future. Fuel cells use a reaction between hydrogen and
oxygen to release electricity, with only waste produced being water.
Leading technologies include the Proton Exchange Membrane Fuel Cell
(PEMFC), the Solid Oxide fuel cell and the Alkaline Fuel cell. In the
future, the fuel cell will primarily be used to replace the internal
combustion engine but may alsso suitable for local electric power
generation.
Renewable Fuels Technology: Renewable sources include
solar - thermal and photovoltaic, wind - on and off shore, tidal, wave,
hydro, geothermal, aqua-thermal, biomass and waste-to-energy -
agricultural waste, energy plantations, landfill gas, sewage sludge
digestion, municipal solid wastecombustion, and thermo-photovoltaic cells.
Nuclear:
The continued role of nuclear reactors for energy supply remains a
source of contention. Some argue that if reactor safety could be
assured, including the transport and disposal of radioactivewaste
and the non-proliferation of nuclear weapons technology assured, then
nuclear is a viable alternative as it is a relatively clean energy
producer. However, radioactive waste is a bi-product with a lifetime of
thousands of years.