From sun light we get the basic type of renewable energy which we call as solar energy.
Apart from sunlight there are other sources of renewable energy, which are water, wind, geothermal and biomass.
These are the renewable energy sources that are currently generating a lot of interest in the minds of different groups of people like scientists, politicians, administrators, media groups, environmentalists and the general public.
This is due to the fact that most of the power that is generated currently is from fossil fuels like coal, oil and natural gas which emit greenhouse gases like Carbon Dioxide (CO2) and cause global warming.
They have been used as the main resources for generating power for several decades due to the fact that they were cheap and were available in huge quantities.
But the scene has changed over the recent years in that their availability has been found to be restricted only for a few more decades.
Oil prices have been going up steadily over the years since the 1970’s oil shocks and had also become a political tool in the hands of the oil suppliers.
Hence people all over the world have been looking for alternative energy sources, which are :
Available in huge quantities;
Available locally or
Within the same region as the consumers,
so that they can be sure about overcoming dependence on foreign suppliers and at reasonable prices.
Let us have a brief look at these energy sources :
Solar Energy Type Of Renewable Energy : Source - Sun light
From sun light, we get solar energy producing heat and light. Sun light gets directly converted into electricity by means of solar cells or photovoltaic (PV) cells made from silicon.
Such PV cells vary from the smallest sizes being used in wrist watches and calculators to big sizes used in large PV arrays made up of several trays containing large sections of them for generating power for residences, commercial complexes, factories, hospitals, colleges, clubs and other various community based structures.
Solar power plants are the devices, which have thermal collectors in different formats to collect the sun's light and energy and concentrate it on to tubes containing water or some other fluid, converting it into steam to drive turbines thus generating electricity.
Solar Power Tower
are different types of solar power plants to generate energy for large applications.
All these devices concentrate the incoming sun's energy and turn it into much higher intensity for producing high pressure high temperature steam.
The typical concentration ranges being :
30 to 100 times in parabolic troughs achieving temperatures up to 400 degrees celcius,
2000 in the case of solar dish to achieve temperature of 750 degrees celcius and
1500 in the case of solar power tower.
Tidal Power Type Of Renewable Energy : Source - Water
It is generated from ocean currents due to the constant changing of ocean water levels. This is due to the rotation of the earth, its gravitational pull, its relative motion with respect to the sun and the moon.
These motions cause ocean tides, which can be utilized to generate power.
There are two methods of generating tidal power.
By utilizing Kinetic Energy : that is, the velocity of moving water, we can generate tidal power in water turbines. Water flow in horizontal direction is utilized in this application.
By utilizing Potential Energy : that is, the difference in the heights of water. Water flow in vertical direction is utilized for this application in a barrage or dam or in a tidal lagoon.
Geothermal Type Of Renewable Energy : Source - Hot Water or Steam
It is power generated from the heat stored under the earth’s surface from times immemorial due to factors such as absorption of solar energy and radioactive decay of minerals.
There are several “Hot Spots” across the world known as tectonic plates, which contain such hot spots. There are eight major and minor tectonic plates on earth.
Geothermal electric plants have been built around these tectonic plates where high temperature geothermal resources are available near the surface.
High pressure steam taken from these spots is used to drive turbines to generate power.
Three types of plants which have been developed so far are
Dry Steam Plants;
Flash Steam Plants;
Binary Cycle Power Plants.
Wind Power Type Of Renewable Energy : Source - Wind
It is the conversion of wind energy into a useful form, such as electricity, using wind turbines.
Biomass Type Of Renewable Energy : Source - Biomass
Wood, MSW (municipal solid waste), crops, alcohol fuels etc form biomass, which act as the sources for generating heat or electricity.
When wood and other biomass elements are burned we get heat, which is used to produce steam, which in turn drives turbines to generate energy.
People throwing their waste into their garbage bins (solid waste mass) gets collected at source by the municipality, transported to nearby open land and used as land fills.
This can be used as a resource in a Waste-To-Energy plants by burning it.
Alternatively due to the decomposition or rotting of the biomass, a gas - Methane is released, which is known as Biogas, sometimes also called Landfill Gas.
Where there is a shortage of open land, the waste is not used as land fills but burned and power is generated.
Whatever may be the type of renewable energy, all these sources satisfy the conditions mentioned above but they are subject to :
among others, which will restrict their wide applications in the immediate future.
All these sources do not give out constant and predictable output as needed.
Sun light is bright when there are no clouds but during cloudy days or during monsoon time sun light intensity is much reduced.
Solar energy plants require large land areas where sun light is available through most part of the year in high intensity so that solar arrays or parabolic troughs or dishes can be set up in the required quantities to generate large scale power to meet the requirement of the community.
Where land availability is not certain there are bound to be conflicts between interested parties.
Wind force is not constant at all times and locations. They are high at high altitudes and off shore locations. They tend to occur at short bursts.
Large scale wind power plants are possible by the setting up of Wind Farms.
Since wind force is high on hills or on off shore locations, to set up such wind farms on these locations and distribute the power generated to the end users over long distances, the utilities will have to make high investments which may be act as a dampener.
Whatever may be the type of renewable energy, we need to do much more work to make it feasible to distribute it to the common folks at affordable costs on a sustainable basis.
Looking at the financial constraints one can understand a few factors as follows :
Renewable energy is fast becoming today's technology from being an academic curiosity a few decades ago.
From theory to lab models to pilot plants to commercial scale models it has reached a stage where many renewable energy plants of varying power outputs have been set up and operating in different spots in the world.
In any field yesterday's technology is always cheap since it has already recouped the initial research and development costs several times over.
When a new technology becomes a practical possibility it will need :
Huge financial outlay;
Favorable terms of loan arrangements as also tax incentives;
Land requirements at less than market rates at least in the initial stages;
Ability to find :
Consultants and business management professionals to market the technology to the end users;
Entrepreneurs to set up small to medium scale business enterprises in addition to corporate entities to carry out the installation, operation and service of the plants;
Institutes to train people for these operations, for each type of renewable energy plants selected etc.
It is quite encouraging to note that many governments are becoming interested in giving a push to the renewable energy technologies by enacting suitable legislation addressing the above parameters and various other challenges so that the people will get the ultimate benefit of renewable energy in the near future.
Social conflicts may raise their heads whenever a new technology becomes ready to take the place of the old technologies.
Here as we have seen, land requirement being huge for setting up the power plants suitable to the particular type of renewable energy, whether solar power plants or wind farms or biomass plants, there will be pressures and counter pressures for the particular piece of land.
One particular land area may become the bone of contention between industrialists wanting to set up power plants and others interested in preserving nature or heritage structures or objecting to the installation of biomass power plant since it may cause health problems etc as the case may be.
It will require deep study and the ability to take the interests of all the stake holders in proper perspective to achieve success.
Then it will only be a selection of the correct type of renewable energy suitable for a particular locality.
2] Energy Information Administration, DOE, US Govt.