A Brief Colonial History Of Ceylon(SriLanka)
Sri Lanka: One Island Two Nations
A Brief Colonial History Of Ceylon(SriLanka)
Sri Lanka: One Island Two Nations
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Back to 500BC.
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Thiranjala Weerasinghe sj.- One Island Two Nations
?????????????????????????????????????????????????Monday, July 17, 2017
Don’t be fooled by obfuscations Dummies guide to solar, wind and grid power
Daily output variation of a large solar power plant in Spain (The messiness is due to passing cloud cover)
by Kumar David-July 15, 2017, 5:22 pm
Controversies
frequently erupt around renewable energy availability, prices and
incorporation in the grid. Much is couched in language opaque to the
newspaper reader. That’s a pity because the citizen eventually foots the
bill and suffers the power cuts. Since I have some slight familiarity
with electricity I am drafting a primer to help layman decode experts
and wag a finger at their obfuscations.
The starting point is an appreciation of the difference between power
and energy; in our context MW (power) and MWh (energy). One MWh =1000
kWh; kWh is a fancy name for a ‘unit’. If you have a 480 horse-power
Ferrari you sure have lots of power but if your petrol tank is near
empty you don’t have much energy to go places. A big MW solar plant is
not much good if there is frequent cloud cover like a Ferrari with an
empty tank. When people con you with solar and wind and talk in MW
(power), ask about energy, the MWh expected per year. Lanka has a
limited number of onshore wind sites and is nowhere near as prolific in
insolation (sunlight falling on the earth) as the Arabian, Thar or
Mohave desserts or the bright and cloudless Chilean Andes. We don’t have
vast uninhabited lands for photovoltaic or wind farms unlike China and
the US; no sites for large, say 500 MW, projects as in Pakistan or
India. The 100 MW first stage of Quad-e-Azam solar (final 1000 MW) in
Pakistan needed 500 acres! An average wind speed of 5m/sec at 50m height
is poor, over 7m/sec is good; few places in Lanka meet the requirement.
The technical catch is that coal, liquefied natural gas (LNG) or
nuclear, if well maintained and if fuel supply is not disrupted, can run
flat out say 85% of the time (capacity factor). There are 8,760 hours
in a year so a 1MW plant can generate 0.85x8760x1 = 7446 MWh average a
year. The story with wind and solar is different. The sun does not shine
at night and seasonal cloud cover bucks expectations. The wind blows
when and where it listeth. Solar and wind plant may provide full output,
absolutely no output, and much of the time partial output. The capacity
factor for solar and wind at a good site may reach 35%, humbler ones
may be constrained to 20%. Therefore, a solar or wind farm will provide
only 25% to 40% of the energy of a thermal plant of the same name plate
rating. A 1MW solar or wind plant at a location with capacity factor say
28% will provide an average annual energy of 0.28x8760x1 = 2453 MWh.
So, talking megawatts (MW) alone is a smokescreen.
The government foolishly dumped the proposed 500 MW coal station at
Sampur and recently turned its back on a 1200 MW Japanese LNG proposal
in the Western Province. Instead the Energy Ministry has opted for a 50
MW solar plant at Sampur. If we calculate as in the previous paragraph,
it has dumped 3.7 TWh of Sampuor energy, and has declined 8.9 TWh of
Japanese LNG energy for a mere 0.12 TWh of solar electric energy (1 TWh =
1 million MWh). Incredible! The silly sods in the line ministry, SEMA
and PUCSL have set us up for a massive shortage of future electric
energy. Pie in the sky talk of 2,600 MW of solar and wind power by 2037,
even in the MWs materialise, will not meet a fifth of the country’s
then electric energy needs.
The within-day, daily and seasonal energy availability of solar and wind
electricity fluctuates. When the sun shines effective costs are good
thanks to rapid technological and price advances. The best sites,
globally, are competitive with coal and LNG – say Rs 9 to 14 per kWh.
The problem is the capital cost of additional (reserve) plant needed
when solar/wind power is unavailable. This pushes the effective energy
cost up by say 30 to 50% depending on the assumptions made in
calculations.
Do the rich subsidise the poor?
There is a peculiarity about our tariffs. Services like state health and
education are paid out of national revenue into budget accounts and are
evenly priced for all. Similarly, at the retail store you do not pay a
different price for sugar, rice or thalana batu depending on your
consumption, income or social class. It’s different with CEB
electricity. Domestic premises consuming 90 units a month pay Rs 9.25
per unit averaged over all component charges; if consumption is 200
units this rises to about Rs 23 per unit and at 400 units a month it is a
shade over Rs 33 per unit. So, there is a commodity specific
cross-subsidy; bad in principle and bad in practice. People get the
municipality to provide different assessment numbers for upstairs and
downstairs and pay Rs 9.25 a unit on each bill instead of Rs 20+ or 30+
rupees a unit on a composite bill. This tariff system should be dumped.
The supply authority should divide revenue needed by units expected to
be sold and charge everyone at a uniform rate. It is mockery to attempt
social justice on a commodity by commodity basis.
The silliness does not stop there. The tariff on industrial and
commercial customers is complicated depending on time of day (this is
reasonable since generation cost at peak time is high), consumption and
type of industry. It varies from more than Rs 25 at peak time to less
than Rs 10 from late night to early morning. But it is irrational to
have so many classes of consumers.
The craziest is religious premises. The charge is less than Rs 2 per
unit for the first 30 units and even at 200 units (average middle-class
household consumption) it is less than Rs 10 a unit! There is a big
cross-subsidy. Subsidising less well-off households is one thing, but
why the devil should I pay to have the gullible misled with myths and
superstitions? Let the dayakayas and parishioners pay.
Net-metering
When the sun shines bright on your old Kadawatta home the electric
energy produced by a roof-top array may be more than needed at that
moment. The rating of plant of course is matched to the highest
insolation at midday. The thing to do is to store up the extra energy
for later. The wind and solar power injected into the Lankan grid in the
foreseeable future will be so small that the system can absorb it
without flinching (without storage). A few hundred MW when the sun is
blazing and wind howling is easy to absorb in a four thousand of MW
system. No special measures such as smart-grids or pumped storage are
needed. It is different in Holland, Denmark and Germany where the sudden
cessation or surge of huge amounts of wind power can panic system
controllers. Wind all over a country will only rarely shut down or surge
up all at the same time but to deal with big fluctuations the system
needs fast acting plant (gas turbines for example) that can kick in
quickly. These spinning and standby reserves have to be entered on the
cost side of a wind or solar balance sheet. Storage systems for
renewables, especially large grid connected plant are now receiving a
lot of attention.
The term net-metering is not used for grid level stuff but for consumer
premises. That solar panel on your roof may be yanking out full power at
midday when no one is home and only the fridge is running. In the
evening, your wife turns on the rice cooker, kids switch on study lights
and you relax in a brightly lit room with a well earned scotch after a
hard days work! (OK, call me an MCP!). Now you need lots of electricity.
The trick is a meter which keeps count of the energy injected into the
CEB and sets it off against consumption when demand is high – hence the
name net. You are billed for net consumption and a surplus can be
carried over as a credit (‘banked’) for months or years.
This is where the dispute about cross-subsidies arises. I said a big
consumer may pay an average of say Rs 30 a unit. If he sees the light
(poor pun) and goes solar maybe his net consumption can come down to 90
units, Hey presto, he pays at Rs 9.25 a unit! So, the argument goes that
the CEB loses lots of money and its ability to cross-subsidise poor
consumers is undercut. Is this correct? Well yes, revenue is top-sliced
and something will have to be raised to recoup it. The most expensive
plant is run at peak time but these rich solar types do not top-slice
their demand at these times. Hence the cost saving to the system from
their ‘returned’ energy is small.
This objection is invalid if time of day pricing (a more sophisticated
version is called ‘spot-pricing’) is used. Credit for energy returned
and charge for energy consumed depend on the utilities cost of
generation at the relevant moment. If you inject 100 units at noon when,
for example, the utilities’ marginal cost is Rs 12 a unit, your credit
is Rs 1200, but if 100 units in consumed during the evening peak when
the utility is running its plant flat out at a marginal cost of Rs 25
per unit, the debit side of your account will show an entry of Rs 2500.
You are in energy balance but not in money balance.
Since our solar and wind penetration will remain minuscule for a long
time it is unlikely to make much impact on overall generation costs. It
is good in principle to encourage renewable energy but not to rush in
like a bull in heat, create future energy shortages and fall prey to the
rapacious oil lobby – which is where we are heading. Trump is cuckoo to
spurn the environment; our half-baked experts and perplexed regulators
are dyslexic and foreswear a measured approach. A US Energy
Administration graph showing how coal usage gradually declined is
reproduced. Other forms of fossil fuel usage have not declined, but
that’s a story I should take up another time.