My Recent Involvements Regarding Renewable Energy in India
by Dr.-Ing. Indradip Mitra, India (PPRE 2003/04)
India has very high targets (e.g. 100 GW of solar, 60 GW of wind by the year 2022 etc) of renewable energy share in the overall generation capacity mix. Accordingly several initiatives had been taken by various authorities in India since past few years. At the moment the grid connected solar of about 13 GW and wind of about 32 GW are installed in India and ongoing continuous drives are existing for reaching the installation targets. Meanwhile the authorities realized that it is not enough to only install RE plants. In order to have a real meaningful existence of high share of RE in the energy mix, various kinds of complex barriers need to be overcome. In a nutshell it is known as the grid integration challenge. Along with several organizations GIZ also started working for mainstreaming the renewables into Indian electricity system since last 8 years or so and recently the large scale integration of renewable energy in the power system is one of the major focus areas of GIZ in India. In this article I am highlighting a few key initiatives related to renewable energy where I was directly involved with GIZ.
(A) Establishment of a large nationwide solar radiation measurement infrastructure
The availability of reliable and accurate solar radiation data is crucial for achieving very high solar installation targets. Similarly, it is also important that project developers, operators and investors can evaluate the real life performance of the solar plants commissioned and actually operating. GIZ, through its SolMap project funded by German federal Ministry BMUB, supported the Ministry of New and Renewable Energy (MNRE) in establishing a network of solar radiation data monitoring units around India, as part of the countrywide Solar Radiation Resource Assessment (SRRA) initiative. The units measure solar and other relevant meteorological parameters. To this end, the project enhanced the exchanges and cooperation between relevant institutions and experts to transfer German experience and know-how in the field of solar resource assessment. GIZ supported the National Institute of Wind Energy (NIWE) in the development of an accurate and enhanced-value database for information on solar radiation and other weather parameters. Such a precise and bankable database is essential for designing and planning for solar power deployment in India. The project also introduced a mechanism for the systematic evaluation and benchmarking of the technical performance of large grid-connected PV plants. A performance benchmarking scheme is developed that enables an easy overview of the performance of solar power plants in different climatic zones, using different technologies, tracking options etc. In this way, a substantial knowledge pool will develop, with which to estimate yields under real operating conditions, during the planning stage as well as to provide valuable feedback for individual plants to enhance their operating effectiveness. In this project along with me Mr. Kaushal Chhatbar, another alumnus of PPRE also worked significantly.
There were several interesting outcomes from this initiative. Some of are mentioned below:
· 121 solar radiation measuring stations have been set up throughout India covering each State by MNRE/NIWE with support from GIZ. This is the world’s largest pyrheliometric measurement network with high precision data logging.
· Sophisticated procedures have been introduced for the quality control, processing and dissemination of data. Quality controlled time series data streams have been generated for all the measuring stations, and monthly reports are also published.
· The Solar Data Sharing and Accessibility Policy (2013) of MNRE was introduced. Data products have been made available to the public, and these are being used increasingly by the solar power industry. By the end of 2014, almost 230 such solar data products had been procured by the users. In 2017 entire data from the measurements stations were made freely accessible for public.
· The typical meteorological years (TMY) for a few locations, with particular emphasis of direct solar radiation for CSP technologies, have been established by combining data gained from the SRRA with satellite-based models.
· Four advanced monitoring stations have been set up, with facilities to measure aerosol optical depth, long-wave radiation, albedo levels and other more specialised parameters.
· Those four advanced monitoring stations have been selected to be the part of prestigious BSRN (Baseline Surface Radiation Network) network of WMO (World Meteorological Organization). This is first time when Indian measurement stations got accredited by BSRN network.
· Calibration laboratory for solar radiation sensors was built and made operational in 2 locations
· Ground measurements were combined with satellite-derived data and a precise 3km x 3km resolution Solar Radiation Atlas of India was launched in 2015. The atlas has several kinds of maps including GHI, DNI and DHI information for last 16 years.
· A procedure for undertaking PV performance benchmarking has been developed. Further testing concluded with samples of monitored data streams from 119 PV plants provided by MNRE. These were located across 12 of India’s federal states and, at the outset of 2014, comprised approximately 25% of the country’s total grid-connected PV capacity. A working PV benchmarking analysis tool, with robust analytical features, has been demonstrated.
· Additional scientific focus was given on the following areas: (a) influence of soiling on radiation sensors (b) advanced methods for gap filling of radiation data and (c) concept for CSP performance benchmarking.
· SRRA data are being used by several other projects like Green Energy Corridors project in the domain of forecasting, balancing and grid integration of solar power
· About 70 academic/research institutions are hosting the SRRA measurement stations. Significant progress have been made concerning the awareness creation and usage of the solar radiation data among the academia in India. Several scholarly studies, thesis works and recent research initiatives have used SRRA database.
You will get more information from the references , , , , , , , .
(B) Initiative on systematic approach towards smooth integration of large scale renewable energy into Indian electricity networks under Green Energy Corridors framework
While the increasing share of variable Renewable Energy (vRE) in the overall generation portfolio is very welcome, the move also poses complex challenges for grid operators and planners. Variable nature of solar and wind power output has significant impacts for the operation and management of power system. In this context the Green Energy Corridors (GEC) project of GIZ seeks to design and develop a concise set of recommendations for decision makers and implementing agencies in India for a better integration of vRE. This is the first major initiative in India to address the issues on vRE grid integration. GIZ is implementing Technical Cooperation with Indian authorities in this field in a very close cooperation with KfW Development Bank who is in charge of Financial Cooperation. KfW is providing concessional loans of more than 1.4 billion Euro for strengthening the central and state transmission infrastructure for evacuating renewable energy.
A large consortium consisting of Ernst and Young, Fraunhofer IWES, University of Oldenburg and Fichtner worked for GIZ in identifying the areas to improve and also provided recommendations with possible solutions. Some of the major areas of focus were:
· Short term Forecasting of vRE generation from solar and wind plants; Designing renewable energy management centres (REMCs)
· Balancing options
· Market mechanisms and designs including ancillary services and capacity markets
· Regulatory measures, grid codes and technical standards
· Human and institutional capacity development related to better grid integration of vRE
You can read some of the reports out of GEC project which are in public domain. Please refer to ref  for them.
Under the framework of this project REMC concept was developed where forecasting and scheduling of renewable energy plants will be coordinated in the near future in India. You may read references  and  for more details.
Another interesting effort was to try to assess the extent and nature of variability power coming from solar and wind installations. This effort was divided into two specific studies. In the first study, the work introduced the concept of short term solar resource variability in general and focusses on its’ quantification and impact in Rajasthan in particular. For the first time, such an attempt has been made for any state in India by using ground-measured global horizontal irradiance (GHI) and direct normal irradiance (DNI) datasets, recorded at ten time-synchronized solar radiation resource assessment (SRRA) sites in Rajasthan. Also, the effect of spatial smoothing and its’ role in minimizing the fluctuations induced by solar variability was investigated in detail. The methodologies, employed during the study, included the calculation of clear sky indexes of GHI and of its’DNI component, the computation of site-pair correlation parameters for GHI, DNI, variability analysis, the evaluation of ‘Percentage change in generation’ and ‘Diversity Filter’ parameters to observe and quantify Dispersion-Smoothing effect. Results suggested that the site-pair correlation is an important parameter to calculate for the estimation of solar power variability. The paper also presents that the event of spatial smoothing results in suppression of minimum 60% percentage of PV power variability in Rajasthan for time intervals ranging from 1 minute to 15 minute. Conclusively, the study shows that in Rajasthan, considerable smoothing exists, which can support large-scale integration of solar power into electricity networks. You can read about this study in reference .
The other study used time series of wind and solar resource data in order to quantify the correlation, smoothing effect, simultaneity and seasonality at various spatial scales over the whole country. Additionally, a simplified load dispatch simulation of the state of Rajasthan has been done, for specific future scenarios. Results of the smoothing effect analysis show that both wind and solar PV output exhibit seasonality and vary with region. Wind outputs exhibits loose correlation as distance between the sites increase, while solar PV output exhibits strong correlation all over the country. So, it makes more sense to distribute the vRE capacity all over the country. Simultaneity factor, a measure of geographical smoothing, is higher and more uniform for solar PV output compared to wind. Combined simultaneity values are even lower than the simultaneity values for wind output and show a large bandwidth for 18 of the Indian States, implying that some states have greater benefits of combining the two sources than others. Results of the dispatch simulation analysis for the state of Rajasthan show high seasonal variability in wind output and considerably less in solar PV output. Daily profile of the solar PV output requires a higher integration effort in terms of backing-down conventional generation on a daily basis, when employed on a large scale. With increased vRE capacity, Negative Residual load occurs frequently, necessitating power export to other states. Plant Load Factor (PLF) of the conventional generating units decreases due to the nature of RE supply. However, peak power needed from firm capacity stays in the same order magnitude as without RE. Conventional generating units will require faster ramping in order to tackle the quick changes in residual load. The average number of start-up and shut-downs, i.e. flexibility requirements, of conventional generating units increases significantly. The results clearly show that the integration of large amounts of vRE into the electricity grid by 2022, cannot be achieved without addressing the key issues. These include – Probabilistic and scenario forecasts of vRE output incorporating correlation information among the different units, Ancillary services and balancing markets, Flexibility requirement for existing and future conventional units, improvements in the Open Access Policy, aggregation of Generators and even loads into individual balancing units and, introduction of ESS into the electricity grid. However, the results also show that the resource potential and smoothing effects are favourable for grid integration of vRE output in majority parts of India. During increasing the share of Renewables in the grid, it has to be kept in mind to avoid too strong spatial concentration of vRE installations in order to use the benefits of smoothing throughout the country.
I believe this attempt at assessing the grid impacts of variable Renewable Energy (vRE) for India could be a foundation block for vRE Integration efforts. You can read about this second study under WP4 of reference .
At the moment dedicated focus is being given on the technique of producing solar power forecasting and its applications in Indian power systems. A consortium led by Overspeed GmbH, University of Oldenburg, Suntrace GmbH and SGS Weather Services is working with National Institute of Wind Energy (NIWE) for development of indigenous models for short term solar power forecasting in India. Another initiative, on virtual power plants, is being undertaken by a consortium of Fraunhofer IWES and ICF India. Vey soon we will get active in the training and capacity building courses for the upcoming REMC operators.
The latest update was the 1st international conference on “Large-scale grid integration of renewable energy in India” which was held during 6-8 September 2017 in New Delhi. Three hundred and thirty experts from 16 counties, including 66 persons from foreign nations, took part in the conference. You can see about the agenda of the event and also can read and download the papers and presentations from the web site regridintegrationindia.org
I must mention here that from the beginning of GEC project University of Oldenburg has been involved with us. Particularly Dr. Detlev Heinemann and his Energy Meteorology group in the University of Oldenburg, Dr. Hans Peter Waldl and his company Overspeed, Mr. Michael Golba were deeply engaged in the tasks of GEC project. At the moment out of current activities University of Oldenburg as well as Overspeed GmbH are very actively contributing to Indian requirements.
I am confident that overall gradual development towards more scientifically structured and matured information for decision making in renewable energy space will become a reality in India soon.
Some references in reverse chronological order:
1. Towards building solar in India-A combined mapping and monitoring approach for creating a new solar atlas; Jana Müller, Indradip Mitra, Theresa Mieslinger, Richard Meyer, Kaushal Chhatbar, S Gomathinayagam, G Giridhar; Energy for Sustainable Development; 2017
2. http://niwe.res.in/department_srra.php (accessed as on 18th October 2017)
3. Impact assessment of short-term variability of solar radiation in Rajasthan using SRRA data; Sujit Kumar Tripathy, Indradip Mitra, Detlev Heinemann, Godugunur Giridhar, S. Gomathinayagam ; Renewable and Sustainable Energy Reviews; 2017
4. Evolution of solar forecasting in India: The introduction of REMCs; I Mitra, S Sharma, M Kaur, A Ramanan, M Wypior, D Heinemann; ISES EuroSun, Palma, Spain; 2016
5. Application of Forecasting in REMCs - Development in India; I Mitra, S Sharma; 16th EMS Annual Meeting & 11th European Conference on Applied Climatology (ECAC), At Trieste, Italy; 2016
6. Green Energy Corridors project reports : energyforum.in/publication-show/items/IGEP-Green_Energy_Corridor.html
7. Performance ratio–Crucial parameter for grid connected PV plants; Ahmad Khalid, Indradip Mitra, Werner Warmuth, Volker Schacht; Renewable and Sustainable Energy Reviews; 2016
8. Solmap: Project In India's Solar Resource Assessment; Indradip Mitra, Kaushal Chhatbar, Ashvini Kumar, Godugunur Giridhar, Ramdhan Vashistha, Richard Meyer, Marko Schwandt; International Journal of Renewable Energy Development; 2014
9. Performance Benchmarking in India. Results from the Project “Solar Mapping and Monitoring – SolMap"; Srivastava A.N. Schacht V, Haeberle A, Mitra I, Kumar A; 29th EU PVSEC ( photovoltaic solar energy congress), Amsterdam, The Netherlands, 2014
10. Quality check procedures and statistics for the Indian SRRA solar radiation measurement network; Marko Schwandt, Kaushal Chhatbar, Richard Meyer, Indradip Mitra, Ramadhan Vashistha, Godugunur Giridhar, S Gomathinayagam, Ashvini Kumar; Energy Procedia; 2014
11. Development and test of gap filling procedures for solar radiation data of the Indian SRRA measurement network; Marko Schwandt, Kaushal Chhatbar, Richard Meyer, Katharina Fross, Indradip Mitra, Ramadhan Vashistha, Godugunur Giridhar, S Gomathinayagam, Ashvini Kumar; Energy Procedia; 2014
12. Field experiences with the operation of solar radiation resource assessment stations in India; A Kumar, S Gomathinayagam, G Giridhar, I Mitra, R Vashistha, R Meyer, M Schwandt, K Chhatbar; Energy Procedia; 2014