Micro hydro power plant in Nepal

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Negative consequences of renewable technology

A major advantage of renewable energy is that it can be regenerated, therefore it is sutainable and will never run out. More importantly, renewable energy is environment friendly and produces little or no waste products that may pollute or have harmful effects on the environment.

Some countries using renewable energy as an alternative source of energy are also showing increased economic benefits, especially in various regional areas. Most of these projects are location far away from metropolitan cities. They have been able to increase the use of local services as well as increase tourism.

One of the general disadvantages of using renewable energy is that it is difficult to generate huge quantities of electricity similar to that using conventional fossil fuel (as it case of PV). Another problem is with the reliability of its energy supply. Since it is naturally generated, renewable energy are dependent on the weather conditions at the time and in the region of use.

It also has another drawback. It is relatively more expensive to acquire and set up the equipments necessary for the generating electricity. However,  initial cost is generally offset by the long term benefit.

Negative consequences of renewable technology

To combat global warming and the other problems associated with fossil fuels, the all nations must switch to renewable energy sources like sunlight, wind, and biomass. However, all renewable energy technologies are not appropriate to all applications or locations. As with conventional energy production, there are environmental issues to be considered. Some of the key environmental impacts associated with renewable technologies especially hydropower is given below.

Hydropower
The development of hydropower has become increasingly problematic in the United States and other developed nations. And small-scale hydro development has not met expectations either.

Environmental regulations affect existing projects as well as new ones. For example, a series of large facilities on the Columbia River in Washington will probably be forced to reduce their peak output by 1,000 MW to save an endangered species of salmon. Salmon numbers have declined rapidly because the young are forced to make a long and arduous trip downstream through several power plants, risking death from turbine blades at each stage. To ease this trip, hydropower plants may be required to divert water around their turbines at those times of the year when the fish attempt the trip. And in New England and the Northwest, there is a growing popular movement to dismantle small hydropower plants in an attempt to restore native trout and salmon populations.

That environmental concerns would constrain hydropower development in Nepal is perhaps ironic, since these plants produce no air pollution or greenhouse gases. Yet, as the salmon example makes clear, they affect the environment. The impact of very large dams is so great that there is almost no chance that any more will be built in the United States, although large projects continue to be build in many developing countries. The reservoirs created by such projects frequently inundate/submerge large areas of forest, farmland, wildlife habitats, scenic areas, and even towns. In addition, the dams can cause radical changes in river ecosystems both upstream and downstream.

Small hydropower plants using reservoirs can cause similar types of damage, but on a smaller scale. Some of the impacts on fish can be mitigated by installing “ladders” or other devices to allow fish to migrate over dams, and by maintaining minimum river-flow rates; screens can also be installed to keep fish away from turbine blades. In one case, flashing underwater lights placed in the Susquehanna River in Pennsylvania direct night-migrating American shad around turbines at a hydroelectric station. As environmental regulations have become more stringent, developing cost-effective mitigation measures such as these is essential.

Despite these efforts, however, hydropower is almost certainly approaching the limit of its potential in the United States. Although existing hydro facilities can be upgraded with more efficient turbines, other plants can be refurbished, and some new small plants can be added, the total capacity and annual generation from hydro will probably not increase by more than 10 to 20 percent and may decline over the long term because of increased demand on water resources for agriculture and drinking water, declining rainfall (perhaps caused by global warming), and efforts to protect or restore endangered fish and wildlife.

In most of the developed countries like US , hydropower may decline over the long term because of increased demand on water resources for agriculture and drinking water, declining rainfall (perhaps caused by global warming), and efforts to protect or restore endangered fish and wildlife.

Fundamental of Solar Energy

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Wind Energy Lecture II

Lecture by Prof. S. Banerjee from Indian Institute of Technology (IIT) Kharagpur

Wind Energy Lecture I

Wind Energy

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conventional and non-conventional sources of renewable energy

What are the conventional and non-conventional sources of renewable energy?

Conventional : Energy that has been used from ancient times is known as conventional energy. Coal, natural gas, oil, and firewood are examples of conventional energy sources. (or usual) sources of energy (electricity) are coal, oil, wood, peat, uranium.

Non-conventional (or unusual) sources of energy include:
• Solar power
• Hydro-electric power (dams in rivers)
• Wind power
• Tidal power
• Ocean wave power
• Geothermal power (heat from deep under the ground)
• Ocean thermal power (the difference in heat between shallow and deep water)
• Biomass (burning of vegetation to stop it producing methane)
• Biofuel (producing ethanol (petroleum) from plants

We hope that all the conventional sources will become rare, endangered and extinct, as they produce lots of carbon dioxide that adds to the greenhouse effect in the atmosphere (uranium leaves different dangerous byproducts).

And we similarly hope that all the non-conventional sources will become conventional, common, and every day, as they are all free, green and emit no carbon dioxide (well, biomass does, but it prevents the production of methane which is a greenhouse gas 21 times more dangerous that CO2).

Renewable energy: Introduction

The energy crisis which began in 1973 caused petroleum supplies to decrease and prices to rise exorbitantly. This crisis forced developing countries to reduce or postpone important development programs, so they could purchase petroleum to keep their economies operating. It created the urgent necessity to find and develop alternative energy sources, such as other fossil fuels (coal, gas), nuclear energy, and renewable energy resources.

Coal is found primarily in industrialized countries, with Latin American and African reserves making up less than 1 percent of the world total. Thus, it is unlikely that this part of the Third World will be able to use large quantities of coal. The nuclear alternative is undesirable; the associated accident risks, waste disposal difficulties, nuclear terrorism, and nuclear weapon proliferation are dangerous in themselves, and make this form of energy excessively expensive (Brown et al, no date). Acquiring nuclear energy from the industrialized world could, moreover, result in greater technological and economic dependence on developed countries. A more feasible alternative to petroleum, coal, and nuclear reactors in developing countries is the direct and indirect use of solar energy, which is renewable, abundant, decentralized and non-polluting.

Climate change factors

Climate change is any long-term significant change in the expected patterns of average weather of a specific region (or, more relevantly to contemporary socio-political concerns, of the Earth as a whole) over an appropriately significant period of time. Climate change reflects abnormal variations to the expected climate within the Earth’s atmosphere and subsequent effects on other parts of the Earth, such as in the ice caps over durations ranging from decades to millions of years.

In recent usage, especially in the context of environmental policy, climate change usually refers to changes in modern climate (see global warming). For information on temperature measurements over various periods, and the data sources available, see temperature record. For attribution of climate change over the past century, see attribution of recent climate change.

Climate change factors

Climate change is the result of a great many factors including the dynamic processes of the Earth itself, external forces including variations in sunlight intensity, and more recently by human activities. External factors that can shape climate are often called climate forcings and include such processes as variations in solar radiation, deviations in the Earth’s orbit, and the level of greenhouse gas concentrations. There are a variety of climate change feedbacks that will either amplify or diminish the initial forcing.

Most forms of internal variability in the climate system can be recognized as a form of hysteresis, where the current state of climate does not immediately reflect the inputs. Because the Earth’s climate system is so large, it moves slowly and has time-lags in its reaction to inputs. For example, a year of dry conditions may do no more than to cause lakes to shrink slightly or plains to dry marginally. In the following year however, these conditions may result in less rainfall, possibly leading to a drier year the next. When a critical point is reached after “x” number of years, the entire system may be altered inexorably. In this case, resulting in no rainfall at all. It is this hysteresis that has been mooted to be the possible progenitor of rapid and irreversible climate change.

Human Influence on Climate Change

Human industrial activities are believed to be adding to the amount of “greenhouse gases” naturally present in the atmosphere. There are mounting proofs that following the industrial revolution of the 18th and 19th centuries, which commenced in Britain and has expanded to several parts of the world, the amounts of of carbon dioxide, methane and other greenhouse gases in the atmosphere has increased somewhat. this leaves room for the suspicion that humans could have been contributing to Global Warming.

Based on scientific results and day-to-day physical evidences, global warming is no longer in dispute. With the the verdict of the fourth assessment report on climate change just released by the Intergovernmental Panel on Climate Change (IPCC), there is also very little contention that man contributes to the heating up of the Earth. However, the question that remains is: how much of the warming is caused by man?

Human activities that lead to production of GHGs are:

Agriculture: During agricultural practices, methane gas (a GHG) is produced when bacteria decomposes organic matter. It has been estimated that close to a quarter of methane gas from human activities result from livestock and the decomposition of animal manure. Paddy rice farming, land use and wetland changes are also agricultural processes that could contribute to the release of methane to the atmosphere. Use of fertilizers for agricultural activities also lead to higherNO2 concentrations.

Deforestation: With the growth of industrial activities has been worldwide deforestation. As part of the photosynthetic process, trees abstract carbon dioxide from the air and release oxygen back to the atmosphere. with deforestation, the number of trees available to take in CO2 from the atmosphere has greatly reduced, leading to more available CO2 and increased greenhouse effect. When forests are cleared, most of the carbon in the burned or decomposing trees escape back into the atmosphere

Fossil Fuels: Fossil fuels is widely used to power our modern day engines and locomotives. The burning of coals, natural gas and oil yields most of the energy used to produce electricity, heat houses, run automobiles and power factories. The burning of fossil fuels to obtain energy to drive these engines lead to production of tremendous amount of CO2 which is released to our environment and increasers the concentration of CO2 in the atmosphere. It is believed that CO2 generated from the burning of fossil fuel accounts for about three-quarters of the total CO2 emissions from human activities.

Refrigeration/Fire Suppression/Manufacturing: Establishments and Industries used to use chlorofluorocarbons (CFCs) in refrigeration systems, and CFCs and halons in fire suppression systems and manufacturing processes.

Other human factors leading to release of GHGs (particularly methane) to the atmosphere include pipeline losses, landfill emissions and septic systems that enhance and target the fermentation process also are major sources of atmospheric methane;

Indicators of the Influence of Human Activities on Climate Change:

Measurements of the concentrations of CO2, CH4, NO2 and other GHGs in the atmosphere over time suggests that these concentrations have been on the increase since the beginning of the industrial revolution that began in the 18th century. A couple of the graphical data is presented on this page to illustrate that man’s activities are possibly contributory to the heating up of our Earth.