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Case for renewables: Dr Narendra Bansal, Delta Group

October 15, 2010

Dr Narendra Kumar Bansal, Consultant, Renewable Energy, Delta Group

Being a major consumer of energy, the telecom sector needs uninterrupted power supply for operating efficiently. But the low availability of power in the country and its poor quality significantly increase the capex and opex of telecom installations, and result in unsatisfactory service quality. The problem of poor power supply is experienced at telecom operators’ installations as well as  in customer premises.

At the telecom installations, the issue is addressed by using DG sets. But operating these DG sets necessitates transportation and storage of diesel, which is a major problem in rural and remote areas. At the customer premises, battery inverters or DC-DC converters are used to tackle the issue. However, the battery remains only partially charged if the power supply is unreliable.

Decentralised distributed generation technologies based on renewable energy sources such as solar photovoltaic (PV) and wind turbine generators (WTGs) address these issues at the operator’s end to a large extent, and are, therefore, considered as the emerging alternative power solutions for telecom networks. The distribution of solar radiation varies from 4.5 kWh per square metre per annum to 6.5 kWh per square metre per annum. This implies that solar solutions are viable across the country. However, wind energy can be adopted as a solution only if the geographical location is appropriate in terms of wind speed.

According to a study conducted by the Committee on Renewable Energy and the Department of Telecommunications, the capex for solar or hybrid solar-wind systems ranging from 10 kW to 17 kW is Rs 2.6 million to Rs 5.1 million. The cost comparison of running the equipment 24x7 on a DG set for 365 days (for an off-grid site) and on the different combinations of solar/wind-solar systems at various loads shows that the latter saves costs from the very first year or within the initial few years. The payback period is six-seven years. In the international markets, this payback period is more attractive. Also, in the future, the cost of solar PV is expected to come down by almost 50 per cent. With this, the economics of solar PV would improve, whereas the same for diesel would deteriorate.

Therefore, it is crucial for the companies to start using solar energy as a fuel with supportive government programmes providing either a 30 per cent subsidy or soft loans at 5 per cent interest. If an entity takes advantage of these programmes, the payback period reduces to three-four years. In spite of the high capex, solar PV is a viable solution as it has no moving parts and most of the systems are passive.

Though fuel cell technology has a lot of potential, the biggest hindrance to its adoption is inadequate hydrogen production, apart from the safety and storage of hydrogen – the fuel is highly inflammable and has to be stored under pressure. Moreover, its recycling cost is very high. Also, the polymer electrolyte membrane (PEM) of the cell needs to be replaced periodically and its cost is almost equivalent to investments required to install a new fuel cell.

Similarly, biomass, which is being seen as a viable option, has many shortcomings. Whenever a company ventures into solar wind or biomass solutions, it needs to consider its density. The density of biomass on a sustainable basis is only 0.2 W per square metre of the land area in contrast to 200 W per square metre for solar and almost 300 W per square metre for wind. Solar and wind densities are low in comparison to the conventional sources, but the biomass density is low even within the renewable options. Therefore, for biomass, a major problem is supply chain management. The biomass required to run a 1 MW gasifier needs to be stored in a large area, which is extremely difficult to maintain. The biomass gasification technology that exists in the Indian market has a major drawback –  partial combustion has to be done at a lower temperature because of material-related issues. As a result, the synthetic gas that is produced has high soot content. This gas reduces the operating life of internal combustion engines.

Therefore, technologies should be deployed with caution. Solar PV, which is a mature technology now with over 30 years of research and development, is the most workable renewable option. A solar PV project may need a large area due to low density, but once installed, its maintenance and operational costs are negligible.

 

 
 

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