Energy from nature

12 Jul, 2015 - 00:07 0 Views
Energy from nature

The Sunday Mail

1007-1-1-SOLARTakaendesa Denhere

Energy is the most important element in the whole universe, particularly earth. It is what keeps the world going; powering vehicles, movement, cooking, lighting.

There are different sources of energy on earth and they are grouped into renewable and non-renewable energy. Non-renewable energy refers to energy that is generated from fossil fuels created millions of years ago such as coal, oil, gas and nuclear energy, this is the leading source of energy throughout the world for electricity. They are deemed non-renewable because they are depleting and soon enough the sources will be exhausted.

Renewable energy is the energy obtained from the continuing flows of energy from the natural environment such as biomass, tidal, wind, hydro-electric and solar energy. Both these sources of energy have their merits and demerits.

However, today we are going to focus on solar energy.

The first thing that we should know is that solar energy is the energy that comes from the sun and is converted into other forms of energy like heat and electricity. Solar energy, as already mentioned, is classified under renewable energy because its supply is constant, it is not depleted when used, compared to fossils which are gradually running out.

Coal deposits around the world are said to be continually supplying us with coal for the next 220 years, nuclear 260 years, oil 40 years and gas 60 years and after that they will be finished. Right now it seems to be a very long time but if we compare this period to the timespan of existence of earth or human civilisation it is a negligible fraction of time. Solar energy is sustainable, clean and friendly to the environment and we will have it as long as the world remains.

Early adoption

From time immemorial, man has successfully manipulated solar energy to his own benefit especially for heating and lighting purposes. In our ancient Shona and Ndebele states the sun was used to dry food, skins and also during constructing houses using earth. In the 5th Century the early Greeks started building structures which trapped heat during the day and it would be used throughout the night because charcoal, their main source of fuel had dwindled in supply.

In North America, especially in the south-western regions, houses were constructed oriented towards the south to capture as much sunlight as possible during winter. The solar energy industry made major strides in the 19th century when Augustan Mouchout built several steam engines that were powered by the sun. Frank Shuman was an inventor and solar engineer from Philadelphia who built the first commercial engine.

The Maadi solar thermal power station was built by Shuman in Egypt near the Nile River. However, the discovery of cheap fossil fuels like gas and oils discouraged the advancement of solar technology. The idea only resurfaced in the 1970s with a new wave of interest in solar energy and it came as a result of rise of energy costs as well as global warming and other environmental and health concerns.

In these modern times we trap sun radiation for the purposes of heating and electricity and I am going to start by explaining the generation of solar electricity. Solar electricity is generated in two ways: photovoltaic and solar thermal electricity.

They are said to be active solars because they use active mechanical equipment to work. Photovoltaic electricity is the electricity generated by capturing sunlight using photovoltaic panels and locally these are what are commonly known as solar panels. Photo means light and voltaic is an abbreviation of Alessandro Volta who pioneered the study of electricity.

Since a layman does not know the meaning of the word photovoltaics, a popular and common term to refer to PV solar energy is solar electricity. Electricity is produced when radiant energy from the sun strikes the solar cell on the panel made of silicon causing electrons to move around.

The action of the electrons starts an electric current which is then transmitted using electric cables.

Solar panels have an advantage in the sense that they can work without emission of gases, have minimal maintenance requirements, have a long lifetime of up to 30 years.

History has it that one of the earliest solar panels, originally installed in Phoenix in 1917, was reactivated, returning to service in 1980 and they worked perfectly.

Such solar systems are usable in any areas which are not connected to the power grid like rural areas and remote places. Households in towns can also be powered by the same. Solar energy is the solution to the power crisis in Zimbabwe.

Germany has no record of having sunny skies but right now she is the world leader of using solar panels with an overall installed capacity that amounted to 38 754MW by the end of May 2015 ahead of China, Japan Italy and the US.

If we have the sun everyday throughout the year then imagine how effective these systems are in Zimbabwe. Electricity generated from solar panels can be used to power up several electronic devices and appliances in our homes as well as lighting.

One of the weaknesses is that it cannot be used to power electrical devices like hot irons, water heaters or hot plate stoves. In Bangladesh there is a rural village called Aharkhandi which was transformed ever since installing solar panels, they now watch televisions and use mobile phones as well as enjoying energy security and entrepreneurs extend opening hours into the night thus increasing revenues.

Solar energy can also be to power businesses, hospitals, industries cutting off a significant figure of energy costs. Boarding schools can take advantage of solar by installing panels so that pupils can do their studies to late hours without power bills to worry about. Hospitals are not left behind because most of their equipment can be powered by solar panels.

In the past decade some of the local hospitals were complaining of patients loosing lives and mortuaries going bad because of power outages.

The second way of generating electricity is called solar thermal electricity or concentrated solar power (CSP). The thermal systems use solar energy to produce electricity but the energy is produced differently from solar panels.

Rather than using cells as in the case of solar panels, thermal systems use solar collectors with a mirrored surface to concentrate the rays onto a receiver generating tremendous heat that will heat a receiver thus heating up water.

The superheated water produces steam that will turn turbines to generate electricity in the same way that coal plants do, the difference is the source of heating that is different.

According to a report by the International Energy Agency titled Solar Energy Perspectives, in 2010 solar heat collectors covered a global surface of about 28 000ha of which 16 500 was from China alone. In Africa there are a few countries that have started constructing such systems; South Africa leads with a number of plants for example Redstone Solar Thermal Power and Ilanga in the Northern Cape Province, Khi Solar One and many more.

PVTech in its 2013 publication on Morocco mentioned that she started constructing a 160MW thermal plant which would be operable by this year and the project is being supported by the German government which has availed £115m.

One of the beautiful things about such systems is that it produces energy 24 hours a day and this is made possible by the fact that solar thermal plants store energy in the form of molten salts. During generation of power there is no greenhouse gas emissions neither are there any global warming effects.

However, it should be noted that solar panels are now gaining pre-eminence over thermal systems largely because thermal systems are very expensive to install while solar panels are cheaper.

As mentioned before, solar energy is used for heating and lighting and much of the time was spent on generation of electricity now let me take you to solar heating. This refers to heating buildings and water using energy from the sun. When using power from the grid anyone can testify that heating using conventional power is very expensive. Geysers, elements and even ovens boost the speed of our electricity meters.

Fortunately the sun can do the same and without any cost! Yes, I mean it, the sun heats for free. Solar water heaters are normally for domestic use rather than commercial.

The solar collector is mounted on an area of direct sunlight like rooftops where it traps sunlight and then convert it into heat which is trafficked to heat up water that is to be used. After the water in the tank has been heated, the hot water is piped through faucets throughout the house, just as it would be with a conventional water heater.

Heated water is usable in homes, clinics, schools for bathing, dish and laundry. In addition solar heat from the collector can be taken around warming up homes which is good news to those who dwell in cold areas like Nyanga.

Solar heating is very economical because it can cut your electricity bills by as much as 50-60 percent.

Fuel shortages in the 1950s forced Israel to turn to solar heating and right now she is the leading in this area with 85 percent of the households today using solar heating systems.

The Israeli parliament, the Knesset, passed a law requiring installation of solar water heaters in all new homes in 1980. In 2005, Spain followed suit by requiring new buildings to be installed with solar water heating systems.

Zimbabwe has not been left behind in this area, a glance at the economic blueprint the Zimbabwe Agenda of Sustainable Socio-Economic Transformation (Zim-Asset) will reveal that the government is taking steps to increase the usage of alternative forms of energy through different strategies like studying solar water heaters, formulating policy and regulatory measures on solar water heaters and then initiate the programme.

Solar energy is becoming more real than people might realise, in fact it is one that is holding the keys to energy in the ages to come. We are already in what might be termed “the Solar Era” where the future economies are powered by nature and energy costs are minimal.

Zimbabwe has started already taking the steps into the future: the solar powered street lights that are currently being installed along Joshua Mqabuko Nkomo and Enterprise Roads in Harare. Gweru is also enjoying the same technology. A lot of rural homesteads are lit with solar lamps sold by a local company which has actually improved a lot of lives.

The Deutsche bank has already declared in their report 2014 Outlook: Let the New Second Gold Rush Begin that solar energy is a “new second gold rush” and this has already started.

Entrepreneurship opportunities are opening up in this field and youths in Zimbabwe can take advantage of this by selling solar products, becoming product distributors, starting services like Solar Appraisals, Independent Solar Consultancy, Nutritional Advice, developing and owning Solar Projects and Panel Cleaning Services.

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