The environmental impacts of energy production
One of the main differences between renewable and non-renewable sources of energy is thier impact on the environment. Renewable sources of energy on the whole are 'cleaner' and less harmful to the atmosphere than non-renewables. However, renewables can have some environmental impacts. Some people think that wind farms are visually polluting, and burning biomass can have a serious environmental consquences in terms of deforestation and the release of carbon dioxide. In less developed countries clearing trees for fuel often damages an areas ecological balance and can lead to desertification.
Non-renewable sources of energy release harmful pollutants, such as carbon and sulfur compounds, into the atmosphere when they are burnt. Transporting fuels from the area of productionto the area of consumptionhas environmental impacts. An obvious example is the movement of crude oil from one part of the world to another by means of tanker or pipeline. There is a danger of an oil spill contaminating the environment where it occurs and transport by tanker uses fuel, which release carbon dioxide and other pollutants into the atmosphere.
Another difference between renewables and non-renewables lies in the scale at which they are used. Renewables resources can often be exploited on a smaller, more localised scale than non-renewable resources. An example, is the mini-hydro systems used for electricity generation in remote Himalayan villages in Nepal. However, this is a generalisation; most hydroelectric power and tidal barrage schemes are as large scale as oil-fired power stations.
In developing countries, particularly in rural areas, 2.5 billion people rely on biomass such as fuel wood to meet thier energy needs for cooking. This figure is projected to increase to over 2.6 billion by 2015 and to 2.7 billion by 2030 because of population growth. In most less developed countries use of fuel for cooking accounts for over 90% of housegold energy consumption because most rural dwellers have no access to electricity.
The use of biomass is not in itself a concern unless fuel is harvested unsustainably. In many countries reliant on biomass, such as those in east Africa, women and children bear the burden of fuel-wood collection - a time consuming exhausting task. In Tanzania the average distance travelled to collect wood is between 5 and 10 km per day. Many children, especially girls, are withdrawn from school to attend this task.
In addition to the human cost of fuel-wood gathering in less developed countries, there are also environmental factors to consider. Increased population pressure in relation to the carrying capacity of the land has led to overuse of the land through a combination of activities, including fuel-wood gathering, over-cultivation and overgrazing. The scarcity of fuel supplies has led to the widespread removal of woodland for firewood. This results in less interception of rainfall, reduced infiltration, faster runoff and greater soil erosion by water and wind.
Nuclear power and its management - Disposal
Nuclear power stations produce high levels of radioactive waste in the form of used fuel rods which have been removed from reactors. In the UK, these are taken to the Thorp nuclear reprocessing plant at Sellafield in Cumbria. Here, reusable uranium and plutonium are seperated out to leave unusable radioactive waste. Thi is currently stored at Sellafield in steel-clad or lead-lined glass containers.
Disposal of Nuclear waste
Nuclear waste has a long half-life (the measure of how long it takes to lose half its radioactivity). The half-life of uranium is measured in millions of years. The material will therefore remain highly radioactive for a very long time and this has to be borne in mind when disposing of it safely. Transport of waste from one part of the country to another is also a problem. Specially designed railway containers have also been constructed and extensively tested.
In the UK, the Nuclear Decomissioning Authority (NDA) formerly Nirex, has responsibilty for disposing of all forms of nuclear waste, some of which does not orginate in this country. It has tried unsuccessfully to find enough sites for disposal.
Disposal of nuclear waste
When examining the potential of a site it is necessary to consider the following factors:
- the geology of the area - the ground must be geologically stable so that there is little chance of underground displacement.
- unemployment figures in that area - jobs will be created by the activity.
- the availabilty of land, which has to be bought for the site.
- transport links to the site, both locally and for transporting waste long distances from nuclear power stations and ports.
- the potential strength of local pressure groups.
- the design features that will be necessary to make the site safe for many years.
- the technology that will be necessary to ensure safe transport, storage and security.
The construction of the site for safe storage of nuclear waste raises a number of issues which include:
- noise and disruption during contruction
- short-term and long-term safety concerns, with particular emphasis on leukaemia and cancer
Disposal of nuclear waste - 2
- potential contamination of water supplies, again both short and longer term
- the effect on farming activites - will crops be safe to consume in the area and will animals become contaminated by grazing on grass, which may be affected by the waste?
- the potential risk of accidents and the worry that the site may become the target of terrorism
- the effects on tourism - will the site destroy the tourist industry of the area or increase visitor potential?
- the 'hiding and forgetting' syndrome - what future problems may arise, which are difficult to predict and plan ahead for?
- if it is located in Cumbria, will the area become too economically dependent on the nuclear industry?
The use of fossil fuels - Climate change
The continued rise in the consumption of oil means a predicted 60% rise in carbon dioxide emissions between 2004 and 2030, mostly from cars, trucks and power stations. More than two-thirds of the increase will come from developing countries as a consquence of fast economic growth and a massive rise in car ownership. The rise will be in addition to thaht which has already taken place over the last 50years.
Views still differ over the degree to which human activity has contributed to global warming. However, there is a growing international consensus that human-induced emissions of carbon dioxide and other gases, for example methane and nitrous oxide, are a major factor causing climate change. These emissions come from, among other sources, burning ever-greater quantities of oil, coall and petrol. The gases trap the suns energyin the atmosphere and cause what is known as the Greenhouse effect. Carbon
The use of fossil fuels - Climate change 2
dioxide occurs naturally and the greenhouse effect keeps temperatures on the planet at a level that makes it habitable, but current carbon dioxide levels are about 40% higher than they were before the Industrial Revolution.
Most observers agree that the less developed world is mroe susceptible to the effects of climate change than the more developed world. This is because poorer countries do not always have the infastructure and resources to counter the effects of climate change. It is not uncommon for single weather events, such as tropical cyclones and floods, to kill thousands of people in regions such as south Asia, southern China and central America. In Africa the UN reports a 40-60% decrease in total water in the large catchement basins of Niger, lake Chad amd Senegal. In a continent already struggling with poverty and famine, climate change is a matter of life and death.
The use of fossil fuels - Climate change 2
As the risks of manmade climate change became better known, the international community began to negotiate a treaty that would define mandatory limits for greenhouse gas emissions. The Kyoto Protocol, adopted in 1997, required that by 2008-12 developed countries should have reduced carbon emissions by 5% from 1990 levels. This was concidered minimal because many scientists claimed that a 50% reduction wuold be needed to achieve climate stabilisation.
When the Kyoto Protocol was developed, poorer countries felt that the rich countries should take responsibilty for solving problems of which they had been the primary cause. Reductions in emissions for developing countries were, therefore, to be phased in over time; targets for richer countries were to be imposed sooner. At the insistence of the US government, several 'flexibility mechanisms' were added to the treaty. These measures included trading carbon emissions credits between nations so that some could emit more if
they helped other emit less. Different countries were given different emission-reduction targets, for example 8% for the EU countries and 6% for Japan.
Although carbon dioxide emissions from developing countries such as China and India are rising rapidly, developed countries are still the biggest emitters. For example, the USA puts nearly 25% of global greenhouse gases into the atmospher. The US decision to drop out of the Kyoto treaty in 2001 was therefore a major setback. When leaving the treaty, the Bush administration claimed it would take its own steps to reduce greenhouse gases. It was worried that meeting its target of a 7% reduction in emissions would affect economic growth.
The use of fossil fuels - Climate change 3
US absence aside, the Kyoto Protocol came into force in February 2005, after Russias accession to the treaty. Meeting with the commitments to reduce carbon dioxide emissions will not be easy because emissions in most countries have risen since 1990.
In December 2007 the UN held a climate-changing convention in Indonesia. The main outcome was the 'Bali roadmap' which started a 2-year process of negotiations on a new set of emission targets. Other points agreed where:
- the transfer of clean technology to developing countries
- aims to halt deforestation
- halping less developed nations to protect themselves against the impacts of climate change, such as falling crop yeilds and rising sea levels
- a framework for developed nations and transnational companies to earn 'carbon credits' by paying for forest portection in less developed countries.
The final text of the 'Bali roadmap' acknowledged that 'deep cuts in global emissions will be required to achieve the ultimate objective of avoiding dangerous climate change'. It was seen as the first step towards a binding deal to be finalised in Copenhagen 2009.
The major causes of acid deposition are the burning of fossil fuels in power stations, the smelting of metals in older industrial plants and exhaust fumes from motor vehicles. Acid deposition consists of the dry deposition of pollutants released by these activities: sulphur dioxide and nitrogen oxide. These chemicals mix with percipiatation, mist and cloud to produce wet deposits of sulphuric acid, nitric acid and compounds of ammonia (acid rain).
Acid deposition causes damage to trees, particularly conifers. It produces a yellowing of the needles and strange branching patterns. It also leads to the leaching of toxic metals (aluminium) from soils, and their accumulation in rivers and lakes, which in turn kills fish. Acid deposition is blamed for damage to building particularly those built of limestone. It can also cause health problems in people, such as Bronchitis and other respirartory complaints. Various ways of reducing acid depostion exist:
- the use of catalytic convertors on cars to reduce the amount of nitrogen oxide emitted in exhaust fumes
- burning fossil fuels with a lower suphur content
- replacing coal-fired power stations with nuclear power stations
- the use of flue-gas desulphurisation schemes and other methods of removing sulphur either before or after coal is burnt
- reducing the overall demand for electricity and car travel