Engineering the correct energy mix to produce electricity | Sunday Observer

Engineering the correct energy mix to produce electricity

An electric power system should consist of a group of generators that fulfil, to the best possible extent, the objectives of stability and affordability. File pic: Lake House Media Library
An electric power system should consist of a group of generators that fulfil, to the best possible extent, the objectives of stability and affordability. File pic: Lake House Media Library

The ‘correct’ mix should finally run a stable grid, delivering electricity at an affordable cost, resulting in affordable prices.

A stable grid is an engineering requirement; to the layman, instability is displayed by frequent power outages, brownouts and blackouts. To the engineer, instability has many different aspects to be analysed, involving a lot of calculations, scenario analyses, more calculations and informed judgements. For the layman, the grid is a group of generators, connected with wires, and he feels that any electrician can fix a generator and connect them with wires, and say “here is your grid”. The layman knows the electrician has no education, so the layman too thinks he can do it himself. So our society is full of such self-appointed electric power system experts.

To the engineer, an electric power system is an engineered grid, that has to provide every kilowatt the customer asks for (with no prior booking), right at the very moment the customer asks for it.

Name a commodity that you get at the same time you ask for it from the vendor? Petrol (five minutes), vegetables (two minutes), rice, dhal, a bus ride, a mobile reload? Hmm! none, but electricity, you ask for it by switching on, and there, it is.

Stability depends on the mix of generating plants and their features. For example, a country’s electricity supply cannot be run with one coal power plant, because if it trips, no one will have electricity. So, there must be a number of power plants, so that loss of one generator will allow others to pick-up. What if the country has only solar power and nothing else? When the sun goes down every evening, or hides behind clouds for days at a stretch, how can you get electricity?

Power system

An electric power system should consist of a group of generators that fulfil, to the best possible extent, the objectives of stability and affordability. There are other aspects, such as national energy security, for which diversity of sources is essential. It is essential that all types of power plants, should abide by the environmental regulations.

Coal and gas power plants have predictable performance but have emissions. Hydropower plants are clean but need reservoirs and end up confining streams to pipes.

Wind power plants have an unbearable noise, solar power plants cover a lot of land space, otherwise to be used for agriculture or forest. Each technology to produce electricity and each site to build power plants have their merits and demerits.

Thus what Sri Lanka should do is exactly what is stated above; build the correct mix of generation, to meet the objectives, and not be swayed by unquantified comments from unqualified people, including politicians, who know nothing about how to engineer an electric power system.

In that mix, there will be coal power plants (for stability and economy), gas power plants (for stability and mid-merit operations and to follow the variations of wind and solar plants, and as dry season backup to hydropower, large and small, for well-known reasons, and wind and solar power plants for their superior environmental credentials.

That’s precisely what our society is not doing; a President says, “I do not like coal power plants; when I went to India they showed me large solar power plants, so we too must do that”; a prime minister said “The gas terminal should be built by my chosen contractor”; at the end, nothing was built, not even wind and solar.

Disturb the long term plan, and then you have had it. Not a single large power plant has been built since Norochcholai was completed in 2014; it takes five years to build a large power plant, but takes one day to buy a diesel generator.

Other countries

What do other countries do? I present the generation mix of South and South-East Asian countries below, in terms of energy input to the grid for financial year 2018 or 2019 (based on data availability), without comment.

See for yourselves, how others are driving their economies with what, while Sri Lanka is lagging behind, one reason being the higher prices and lack of confidence on future electricity supplies.

One last word of advice to readers, politicians and journalists: if you think you can decide what should be the generation mix in the country, then do not encourage your children or grandchildren to study engineering. You can make those calculations and decisions yourselves. 

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