Exploring Renewable Energy (I)

Solar Energy

Recently, a group of friends and I were arguing about the advantages of solar power (because that’s what engineers do; sit around and talk about the sun!) and one told a joke that impressed me so much I have to share it:

An executive is giving an interview. The interviewer asks: "What about expanding oil production?"

A: "We own the oil."

Q: "What about natural gas?"
A: "We own the natural gas."

Q: "What about solar energy?"
A: "We own the su ... Solar energy isn't practical."

That executive speaks up for a lot of people because for all means and purposes, solar energy is not ‘practical’; the low output coupled with expensive panels and batteries make the fact that strong sunshine is not always predictable pale in comparison.

However, solar energy is growing technology-solar panels today produce twice as much electricity as earlier models-whose benefits cannot be ignored. The minimal cost of maintenance and low space requirements make a big difference in our power infrastructure; not to mention the benefits to the environment.

I say it’s time we ordinary citizens lead the way in exploring this clean, renewable energy source to power our homes and communities; after all the sun is an insatiable energy source-all we have to do is screw a solar panel onto the roof.

Think about this, in connected parts of the country, your household would not necessarily need batteries for nighttime as it is connected to the power grid; the concept is one of hybrid power whereby during the day you use solar power and at nighttime use grid power-slashing your electricity bill significantly; also, if your house produces more electricity than you need, it can go back to the grid for others to use and EWSA would give you credit for the excess power (using net metering) and consequently reduce your bill even more.

Let me break you out of your reverie with some bad news; it is not a cheap venture! In fact, this is unrealistic unless the government encourages this move by paying a fraction of the cost for the panels: to have the household system setup requires between Rwf 9-20 million in order to supply the 1-3kW of photovoltaic’s required of a normal house.

Since many of us don’t have that kind of money lying around, it is good to at least know that all hope is not lost! With our over 250-kilowatt solar plant, Rwanda is far ahead of the rest of continent in exploring green energy solutions and this should only be the beginning.

Given Rwanda’s location vis-à-vis the equator and the sun angle, even during ‘low’ months, solar panels can absorb about 85% of the sun’s energy-we are at clearly at an advantage compared to countries further away from the equator that have capitalized on solar energy.

But solar panels are not an exclusive way to exploit the sun’s riches; one other method is a solar thermal plant. Using parabo lic mirrors, the mirrors track with the movement of the sun to focus sunrays onto a glowing tube of synthetic oil; the hot oil tube passes through a water vat creating pressurized steam that turns turbines to generate electricity with no emissions! One caveat to this method in Rwanda is the fact that large open space is needed for each solar farm and that kind of land is not readily available in Rwanda.

With these grim prospects, it might seem like the interviewed executive was right on the money but solar energy is going to be around for a while (a $50 billion global industry) contributing to our energy solutions and for the critics, at the very least allowing your great grandchildren to inherit a sustainable environment.

Ends