Contribution of Renewable Energy to India's Southern Grid

There is publicly available data on the daily contribution of renewable energy to the southern grid from May 11, 2010. Almost all of the renewable energy contribution into the southern grid come from hydroelectric and wind generation. We are aware of some grid connected solar energy projects coming online, but the capacity is too tiny right now to consider and moreover SRLDC does not report solar generation separately for us to track easily.

If we plot the renewable energy generation against the total energy generation generation we get the following chart (Data from May 11, 2010 to July 12 2014).

Southern Grid: Contribution of Renewable Energy (Click for a larger version)

The light blue series is the percentage contribution of  renewable energy to the total energy generation. It is plotted against the secondary (right) axis.

The records for each of the series from the chart are:

• Maximum hydro generation - 201.99 GWh on Aug 8, 2013
• Maximum wind generation - 125.13 GWh on Jun 25, 2014
• Maximum total renewable generation - 274.63 GWh on Aug 8, 2013
• Maximum % of renewable generation - 38.5 % on Aug 7, 2013

It can be seen that there were instances in the monsoon season of 2011 and 2013 where renewable energy generation touched more than 30% the grid energy generation. Maximum renewable generation happens typically during the monsoon season of south India because it coincides with both the wind season and the rainy season when reservoirs typically are getting full and local electricity boards maximizes the generation of cheap hydroelectric power rather than let reservoirs reach max capacity. This  copious hydro power generation can be seen as peaks in the red line. This is not seen in 2012 - the red line representing hydro power generation stays low (in fact dips) during the monsoon months. The reason for this was that 2011 and 2013 were above average monsoons with +2% and +6% departures from normal while the monsoon of 2012 was a below average monsoon with -7% departure from normal.

This can be seen in the following rainfall maps from IMD.

Rainfall map for the monsoon of 2011

Rainfall map for the monsoon of 2012

Rainfall map for the monsoon of 2013

So far this year (2014) the monsoons had been deficient, but the rains during the last two weeks give a glimmer of hope for the currently dire hydro power situation in southern India. We will revisit this subject at the end of 2014 monsoon season later this year.

Sources:
[1] Generation Data : http://srldc.org/
[2] Rainfall Maps : IMD
      - 2011 - http://www.imd.gov.in/section/nhac/dynamic/mon2011.jpg
      - 2012 - http://www.imd.gov.in/section/nhac/dynamic/mon2012.jpg
      - 2013 - http://www.imd.gov.in/section/hydro/dynamic/rfmaps/seasonal/mon2013.jpg

BusinessLine Report on the Challenges of Utilizing the Full Potential of Wind Power in TN

There was an excellent article published in BusinessLine dated June 23rd, 2014 on the challenges faced by the grid managers in Tamil Nadu in accommodating the whole of the energy generated by wind power producers.

Inquiring minds may wish to read the article in full.

Handling wind power: TN faces many a challenge

Some important quotes:

Even now, 4-5 hours of wind power generation is not being taken, despite there being sufficient transmission infrastructure, says PP Gupta, Managing Director of Techno Electric, whose subsidiary, Simran Wind Project, owns 190 MW of capacity in the state.

You can handle infirm wind if you have sufficient ‘peaking capacity’, or power plants that can very quickly ramp up generation when required. Fortunately, Tamil Nadu has four such power plants – Basin Bridge (196 MW), Samalpatti (100 MW), Madurai Power (100 MW) and Pillaiperumal Nallur (330 MW).

These capacities can quickly come online. For instance, the GMR-owned Basin Bridge power plant can ramp up from zero to 20 MW at the rate of 2 MW a minute, and from 20 MW to 50 MW at one MW a minute. 

 Finally the article concludes with:

In the absence of peaking capacities, the wind power capacity in the state will continue to be under utilised, experts note.

Our previous post on wind energy must be read in the context of this report - that the wind energy generation capacity in TN is persistently underutilized because of grid management concerns .

Southern Grid: Wind Energy

The SRLDC daily reports started publishing daily wind energy generation as an entry separate from 'Others' starting from May-10, 2010. So now we have over 4 years of data of wind energy generation of the southern grid, which should be sufficient to show us the relevant trends. This is a very important data point because the southern grid connects to a large part (around 10GW)[2] of the grid connected wind farms in India.

Wind energy generation in south India follows a very clear seasonal pattern. There are quiet months (November to April) and busy months (May to October). During the lean months typical generation is less than 20 MUs per day and during the windy months the daily generation can exceed 100 MUs with the existing installed capacity.

This is the plot of the data as-is - from May-10, 2010 to July-10, 2014 :

Southern Grid: Wind Energy Generation 2010-2014
(click for a larger version)

The day to day generation data can be quite noisy and can be difficult to track and to observe trends. I prefer the 7-day moving average to smooth out the short term variations.

Southern Grid: Wind Energy Generation 2010-2014 7-day moving average
(click for a larger version)

It can be seen that the energy generation has increased substantially from the 2010 base. Generation for the years 2013 and 2014 had been approximately the same although 2014 had seen new daily energy generation records in excess of 120 MUs. Although there had been substantial recent efforts in Tamil Nadu at improving the grid infrastructure to improve the capacity to evacuate wind energy, more investment and effort seems to be needed to bring about observable difference. The installed capacity for 2013 and 2014 remain almost the same. The substantial improvements in 2011, 2012 were most likely due to new capacities coming online, although the evacuation infrastructure remained constrained.

Now we are almost half way through the wind season of 2014. So the grid improvements coming online later this year could probably only be seen only during the 2015 wind season.

Sources:
[1] Data: http://srldc.org/
[2] Wind Power in India (Wikipedia): http://en.wikipedia.org/wiki/Wind_power_in_India