Efficient utilisation of power remains a key concern for operators and infrastructure companies. To meet this demand, green power is being considered as a viable alternative and power companies have introduced a host of new products and solutions.
Green Power Solutions – Tower companies explore energy alternatives for rural India
Telecom operations in India are characterised by falling revenue realisations per minute, increasing minutes of usage, falling average revenue per users (ARPUs), increasing passive capex spend, deteriorating grid power availability and increasing operational costs. New rollouts also entail higher opex and lower ARPU margins, resulting in strained earnings before interest, taxes, depreciation and amortisation. The success of a telecom operator depends on several factors such as the ability to provide minutes at the lowest possible cost, developing new and innovative value-added services, cutting operating expenditure and attracting a higher number of subscribers.
Available grid power is often unreliable or is prohibitively expensive. Consequently, telecom towers will be heavily dependent on off-grid power. The main off-grid power sources for telecom towers one diesel generator (DG) sets, which are expensive, and require regular refills and maintenance. Moreover, diesel is subject to theft in rural areas. Finally, the price of diesel fluctuates considerably and constitutes a high proportion of opex.
The main challenge before operators and infrastructure companies is that 35 per cent of a site’s opex is related to energy costs. Moreover, 70 per cent of the site’s downtime issues are linked to the passive infrastructure present at a site. In this context, green power is a viable solution. The challenges associated with such an alternative are as follows:
Concerns about green power limitations on network upgrades/evolution.
ACME Tele Power offers an entire portfolio of solutions for various site-related challenges. For instance, mounting operational costs at a site may be curtailed with ACME Tele Power’s 5 kW DC Powerhouse, which lowers back-up and air-conditioning costs. Similarly, site downtime can be reduced with NextGen thin-plate technology and a very high MTBF (mean time between failures) generator. Other alternatives include a nextgeneration green shelter; a DC-powered cell site comprising an indoor or outdoor base transceiver station (BTS); a fuel cellpowered cell site solution; hydrogen fuel cells and solar-powered cell sites.
Alok Kamal, Head, Technical Solutions, Alternative Energy, ACME Tele Power
The mobile subscriber base touched 420 million during the first quarter of 2009 and the figure is expected to reach 500 million by 2010.
In tandem with this growth, it is expected that the number of new BTSs to be set up in the country by 2011 will exceed 200,000.
Currently, the power requirement of a BTS varies from 1,300 watts to 2,500 watts. BTS powering systems are based on grid supply, which is the primary source of power, while DGs act as standby sources and storage batteries as secondary sources.
In the case of an indoor shelter, where maintaining a specific temperature is necessary, the DG needs to be switched on to power the air conditioners and maintain the temperature. Battery capacity is not fully utilised though.
The current powering model for BTSs, however, has several drawbacks.Base stations are typically power-intensive units. DG sets require regular maintenance and diesel thefts are very common.Moreover, the price of petroleum products is continuously rising and grid supply in rural areas is erratic and often unavailable, thereby requiring the DG sets to run for long periods of time.
The key strategies for optimising the power requirements of a BTS include deploying outdoor BTS equipment that does not require air conditioning; BTS with remote radio heads (RRHs) should be placed next to the antenna mount to eliminate feeder loss; fibre-based Ethernet can be utilised for establishing connectivity between RRHs and the base band, thereby eliminating the need for coaxial feeders.
The portfolio of industry offerings for energy-optimised BTSs include the LME 2111, with a power consumption of 450 watts; the ZTE R 60 U, with a power consumption of 400 watts; and the Vanu SDR, with a power consumption of 650 watts.
Alternative energy sources can also be used for powering a BTS site. In fact, a number of technologies amongst alternative energy sources are at different stages of evolution. These, coupled with one or more sources, may be deployed with or without DG sets.
Such sources of energy offer multiple advantages. For instance, these sources offer a clean and green energy source, and would help bring down capex levels with operating costs being almost nil as these energy sources are free. Maintenance and replacements are very low compared to diesel-driven sites. Also, carbon credits can be a revenue stream from green sites.
Available alternative sources of energy for powering BTS sites include solar-DG hybrids, wind-DG hybrids, solar-wind hybrids, biofuels and fuel cells. Of these, solar energy is the most mature technology, offering a high conversion rate of power from light. The main advantages of this source include the presence of no moving parts and therefore, no maintenance cost, and a clean, free energy source.
In the case of wind-based systems, smaller systems can be mounted on existing radio masts, thereby reducing costs.Moreover, horizontal wind turbines are more efficient and, today, systems with low “cut-in” speeds of 2.4 m/sec are available. However, several challenges remain.For example, site selection must be carefully done for deployment of wind turbines. Moreover, wind velocity is often erratic. Thus, one would need an efficient charge controller and a sink for the excess power generated.
The third source of energy ?? biofuel ?? is commonly produced by the trans-esterification of vegetable oil or animal fat feedstock.
A.K. Nagpal, Head, Telecom, Su-Kam
Power Systems Power supply in the rural areas is characterised by little or no access to grid power, poor quality of grid power with long power outages, a wide range of grid voltages and high exposure to lightning. Other characteristics include poor environmental conditions, non-accessibility to power sources and high maintenance expenditure.
In order to improve power efficiency, Lineage Power has introduced a portfolio of products. These include IDA, Active Rectifier Management and the Lineage Priority Source. These products are aimed at improving efficiency and energy management, increasing rectifier efficiency to 96 per cent, optimising plant level efficiency, reducing distribution losses through architectural improvements, improving costs and reliability, optimising operations, enhancing remote visibility and control, integrating solar, wind and hydro fuel cells and offering new battery technologies.
Dr V. Joseph Thottuvelil, Director, Technical Marketing and Applications Engineering, Lineage Power
