The Dark Side of Renewable Energy
In a recent attempt by India to honour its commitments under the Paris Accord, tenders were up for bidding for construction of solar energy plants. This bid was won by Acme Solar – a joint venture between Acme an Indian developer, and SBG Cleantech – whose shareholders include SoftBank of Japan. The projected selling price of electricity from the plants is virtually the lowest in the world - at Rs.2.44 ($0.04) per unit (kWh).
This is a shot in the arm for the shift from thermal power generation to renewable sources like wind, hydro or solar electricity generation techniques. However, as always, the most curious aspects of Indian policies are the devils in the details.
In this case, the tenders excluded one of the most fundamental aspects of power generation - grid safety and continuity of power generation. In a power grid where multiple devices are operating to provide power, a transient problem with one device, say clouds over some part of a solar farm, can cause the entire grid to fail by increasing load on others. This is extremely common in renewable systems, due to their reliance on natural phenomenon. A relatively new technology, called Low Voltage Ride Through System (LVRT) allows the system to independently adapt by preventing an abrupt disconnection. If a problem is more persistent, usually a period longer than 5 minutes, LVRT safely disconnects the problematic portion and alerts the operator for human help. The concept can be employed for any of the three major renewable systems, wind, hydroelectric and solar. It can also operate in a grid combining renewable and non-renewable generation systems. While LVRT can be easily deployed at the time of installation, retrofitting the system is extremely costly and can easily make the commercially impracticable. Thus, regulators across the world are mandating such systems for new projects.
In a document dated November, 2013, The Central Electricity Authority enumerated various instances of power failure, owing to the variability of wind and solar power, adversely affecting load generation balance and varying demand for reactive power, with consequences for voltage stability. Most notably, one of the instances led to tripping of 765 kV Sholapur- Raichur transmission line thus disturbing the whole of Southern Region Load Dispatch Center.
In an October 2013 notification, India’s Power Ministry mandated LVRTs for wind turbine grids over a certain power generation threshold. As per the regulation, new generators connected after April 2014 are required to meet the requirement, but to no avail. No LVRT protections have so far been provided by the wind energy generators. Not only has the regulation been flouted with impunity, there is no direction from the government on retrofitting, or otherwise mitigating old generators without LVRT systems.
In Southern Regional Load Despatch Centre v. Tamil Nadu State Load Despatch Centre and Ors (Petition No. 420/MP/2014) the Central Electricity Regulatory Commission extended notification to solar electricity generation, requiring LVRT systems in solar farms as well. The commission’s representative in his arguments stressed that the large scale deployment of solar energy systems necessitated grid protections in consumer interests. Rooftop systems, however, which are not usually connected to a grid, were excluded from the purview of this decision.
A 2013 Central Electricity Authority report noted the challenge from variations in wind and solar power generation balance impacting voltage stability. It also identified sudden loss of power generation due to lack of LVRT protections as the critical bottleneck to the use of renewables in India’s power consumption patterns.
On the basis of this mounting expert evidence, the CERC had mandated such requirements in all future projects. However, the Acme solar tender, while path breaking, did not require LVRT protections from the operator. Even State Electricity Regulatory Commissions, which were directed to make suitable provisions in their relevant regulations, have chosen to look the other way.
The Indian Wind Power Association, a trade group, estimates that around 11% of Wind Turbine Generators are those in which retrofitting LVRT is not commercially viable. Known as "stall type” generators, around 2-3% of new annual additions continue to be of this kind, further aggravating the issue.
Show me the Money
The entire controversy centres on whether this constitutes a “change in law”, thereby making State Electricity Boards liable for the increased cost of installation. The Regulatory Commission conceded to this fact, but a corresponding notification to this effect still remains missing from most State Electricity Boards – with the technical as well as the cost factors still uncertain almost all over the country, the future of sustainable renewable energy in the world’s third largest polluter hangs in balance. The world should be worried.
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