analyse information from secondary sources to discuss and evaluate the potential uses of photosynthesis in replacing materials presently obtained from other non-renewable resources
Some sources of information are:
Biomass Program
US Department of Energy, Energy efficiency and renewable energy, Biomass program, USA.
Plant Oils
CNN, USA.
Sample information: Potential uses of photosynthesis in replacing materials presently obtained from other non-renewable resources.
Fuels
Fuels produced from biomass (a general term for carbon based matter from plants produced by photosynthesis) provide energy for use in cars in some parts of the world. Ethanol produced by the fermentation of sugars and starches is used alone or added to petrol. There is potential to develop this source of energy to replace or prolong the use of petrol made from non-renewable petroleum resources. At present large amounts of land would have to be used to support the production of sufficient biomass to meet the world’s current need for petroleum products. Large amounts of energy in farming methods (fertilisers, petrol for harvesting machinery) would be needed and the process is not viable at present.
Plastics
Plastics and various polymers are made from non-renewable petroleum resources. It is currently possible to produce plastics (PLA, PHAs and PHBs) from biomass materials using the action of micro-organisms. The development of these plastics has two advantages: the earth’s limited reserves of oil will be preserved and the plastics are biodegradable, reducing pollution and maintaining the cycle of raw materials.
Electricity
Most electricity used in homes and industries comes from burning fossils fuels. It could be possible in the future to harvest trees to replace fossils fuels. At the moment such large quantities would be required that this is not viable, except on a small scale. Problems associated with burning wood for energy (pollution from particulates, carbon dioxide and sufficiently rapid replacement of trees) are yet to be solved. In the USA biogas made from biomass by partial combustion, is used to produce electricity in a gas turbine. There is potential to develop this use of energy provided by photosynthesis on a larger scale.
Fibres
Fibres produced from plants could replace synthetic fibres produced from petroleum. Rayon is produced from the biopolymer cellulose (the main constituent of plant cells walls). Rayon is produced commercially at present and could replace other fabrics like nylon made from fossil fuels.
Ethene
Ethene is an important raw material for the manufacture of plastics, including polyethene and PVC, and halogenated hydrocarbons for refrigerants and solvents. If sufficient glucose could be produced by bacterial digestion from cellulose and then fermented to produce alcohol, it is chemically a simple process to produce ethene by dehydration. The same problems of land usage and energy inputs to produce the biomass by photosynthesis do not make this a viable process at present but it is a direction for future research.