Renewable Energy Sources

Renewable energy systems use resources that are constantly replaced and are usually less polluting. All renewable energy sources – solar energy, hydro power, biomass and wind energy have their origin in activity of the Sun. Geothermal energy which, because of its inexhaustible potential, is sometimes considered as renewable source is getting energy from the heat of the earth. In using each of renewable sources have advantages as well as disadvantages. Table below resume generally advantages and disadvantages of some renewable energy resources.

Renewable energy is a domestic resource that has the potential to contribute to or provide complete security of energy supply. Countries that depend on imports of fossil fuel resources are in danger due to the risk of sharp rise of the cost of imported energy (mainly oil). This is particularly so for developing countries, where the oil import bill adds every year to the problem of financing an already large external deficit.

Renewables are virtually uninterruptible and is of infinite availability because of its wide spread of complementary technologies - thus fitting well into a policy of diversification of energy supplies. Renewable resources are well-recognized as a good way to protect the economy against price fluctuations and against future environmental costs. Technologies based on renewables are largely pollution-free and make zero or little contribution to the greenhouse effect with its predicted drastic climatic changes. In addition, they produce no nuclear waste and are thus consistent with environmental protection policies, building towards a better environment and sustainable development.

Type of renewable energy	Advantages	Disadvantages
Solar	Always there; no pollution	Low efficiency (5-15%); very high initial costs; lack of adequate storage materials (batteries); high cost to the consumer
Hydro	No pollution; very high efficiency (80%);little waste heat; low cost per kWh; can adjust kWh output to peak loads.	Fish are endangered species; sediment build up and dam failure; changes watershed characteristics; alters hydrological cycle
Geothermal	Very high efficiency; low initial costs since already yields steam	Non-renewable (more is taken out than can be put in by nature); highly local resource
Ocean Thermal Energy Conversion	Enormous energy flows; steady flow for decades; can be used on large scale; exploits natural in the ocean	Enormous engineering effort; extremely high cost; damage to coastal environments
Tidal Energy	Steady source; energy extracted from the potential and kinetic energy of the earth-sun-moon system; can exploit bore tides for maximum efficiency	Low duty cycle due to intermittent tidal flow; huge modification of coastal environment; very high costs for low duty cycle source
Wind	None on large scale; supplemental power in windy areas; best alternative for individual homeowner	Highly variable source; relatively low efficiency (30%); more power than is needed is produced when the wind blows; efficient energy storage is thus required
Hydrogen Burning	No waste products; very high energy density; good for space heating	No naturally occurring sources of hydrogen; needs to be separated from water via electrolysis that takes a lot of energy; hydrogen needs to be liquefied for transport - takes more energy.
Biomass Burning	Biomass waste (wood products, sewage, paper, etc) are natural by products of our society; reuse as an energy source would be good. Definite co-generation possibilities. Maybe practical for individual landowner.	Particulate pollution from biomass burners; transport not possible due to moisture content; unclear if growing biomass just for burning use is energy efficient; large scale facilities are likely impractical.

Social Problems Related To Energy Use

Beside environmental problems associated with large-scale use of fossil and nuclear fuels and the problems with sustainability there are also social problems arising from present trends of energy utilization.

Political and economic problems; In the earlier stages of the industrial revolution, fuel sources were local and widely distributed. Industrial activity tended to grow in areas where local sources of coal were available. As the transport associated with industrialisation spread and developed, fuels began to be transported from more and more distant places. Now, with the most accessible sources of oil and gas depleted, fuels are transported around the world from small number of major producing areas. The result is that the major industrial nations have become dependent upon supplies from those producing nations, in particular oil from the Middle East, and are highly vulnerable to disruption of these supplies. This vulnerability and dependence has been a major factor shaping world politics. A series of major economic and political crises has resulted from Sues crisis in 1956 to the 1970s, oil crisis to the Gulf war in early 1990s. Since the producing nations are generally weak militarily and the consuming nations are generally stronger, latter are under pressure to dominate the former economically, politically and if necessary, militarily to maintain access to oil (most important fuel today).

Oil price depends on political situation and each conflict in oil sensitive region leads to higher energy prices. World economy is thus shaped with such conflicts.

Vulnerability due to centralisation; A related aspect of vulnerability in the present form of industrialisation is the centralized nature of fuel production and distribution. Electricity is generated in relatively few, very large power stations, and distributed through the country. Oil is imported in giant tankers, and converted to fuel in large refineries for further distribution. Concerns have been expressed that these large, vital installations offer potential target for terrorists or military opponents. As has been seen in recent years in the Middle East (Gulf War), the result can be massive ecological damage as well as economic devastation. The normal response to such vulnerability is to put greater resources into security and to increased level of protection. High level of centralisation leads also to problems with employment. Decentralized energy production and utilization which is the case of renewable energy sources can create much more new jobs than centralized fossil fuel installations.

Military dangers from nuclear proliferation; Nuclear weapon proliferation is one of the biggest threat to the world peace today with several countries already in or trying to be a member of “nuclear club”. In developed countries nuclear electricity industries grew out of nuclear weapons development. The earliest nuclear reactors were built to produce material for nuclear bombs. There has always been a close connection between the two terms of the technology used, so that military spending on research and development for nuclear weapons technology has in effect been a major subsidy for civilian nuclear electricity industries. Nuclear fuel is not directly useful for nuclear weapons. Much further processing is needed. However, for a country wishing to develop nuclear weapons without publicly revealing the fact, an obvious approach would seem to be combine weapons development with a nuclear electricity generation industry.