Anil Trehan is Vice President of Energy Solutions for CommScope. In his 25 years of work experience, Mr Trehan has held several technical management and engineering positions at Avaya, Lucent Technologies, AT&T – Bell Labs, and General Electric.
Anil Trehan has a masters and bachelors degree in engineering.
The mobile communications sector can benefit from improving power efficiency and harnessing renewable energy solutions. Energy efficiency holds the key to lowering both costs and carbon emissions in mobile networks. Numerous proven, high-performance technologies exist today that can reduce base station power consumption. What tools are available to operators wishing to streamline their network power generation and consumption?
Renewable energy generation and power efficiency are inextricably linked to economic development across Europe. Transport, manufacturing and many other industries that form the backbone of developed economies well know the strong ties between profitability and the cost of energy.
Nevertheless, European governments have set some of the most ambitious targets for energy efficiency. In the UK, energy demands are set to triple by 2050 but the government is also committed to cutting carbon emissions 50 per cent by the same date. The UK’s 2011 Carbon Plan recently reaffirmed its commitment to engage with the EU to reach a 30 per cent emissions reduction by 2020 in the areas of transport, energy, product standards and finance.
The mobile communications sector is another industry that can hugely benefit from improving power efficiency and harnessing renewable energy solutions. With an estimated 523.6 million mobile connections in Western Europe, the meteoric uptake of mobile devices has meant that operators must now support huge networks of energy hungry base stations across multiple markets.
Energy costs weigh heavily on every mobile operator’s bottom line. Increasing consumer demand for both universal coverage and capacity has led to the rapid proliferation of base stations. Operators now face spiralling costs, with the annual energy expenditure for powering on-grid base stations predicted to grow to €15.8 billion by 2013. Meanwhile, the number of off-grid base stations powered by generators is projected to reach 640,000 in 2012 and consume €10.5 billion worth of diesel fuel.
However, a multitude of proven, high-performance technologies exist today that can reduce base station power consumption by as much as 40 per cent. With Analysys Mason predicting that retail telecoms revenue will decrease by five per cent between 2010 and 2015 due to greater competition and saturated markets, the potential reduction in OpEx that energy efficiency can bring is hard to ignore. So what are the options?
Renewable power generation
Renewable energy sources such as solar, wind or sustainable biofuels provide an alternative means of powering base stations. However, such solutions are often dependent on the right conditions (e.g. sunlight/wind) and are therefore a less than perfect solution for a base station to rely on alone. Nevertheless, when used in tandem with a backup power source, solar and wind technology can be relied on for peak period power generation.
Once photovoltaic cells or a wind turbine is installed, power is almost free as these solutions require very little maintenance compared to traditional diesel generators. The GSM Association has set a target of powering 118,000 base stations through renewable sources by 2012. Achieving this target would save up to 2.5 billion litres of diesel per year and cut annual carbon emissions by up to 6.3 million tonnes.
Another power source being rapidly adopted by mobile operators is hydrogen fuel cells. Fuel cells offer a robust alternative for backup power supplies, entirely replacing lead-acid batteries and diesel generators. Hydrogen fuel cells are extremely safe and reliable – indeed they can significantly extend the run time for backup power. They also have a faster and more reliable turn-on response, reaching full power in less than a minute compared to three or four minutes for diesel generators. Better still, the only by-products of hydrogen fuel cells are heat and pure water, making them environmentally friendly.
Besides reducing carbon emissions, the total cost of ownership for providing backup power with hydrogen fuel cells is also much less than that associated with batteries or diesel generators. Fuel cells require considerably less maintenance than diesel generators, and also take up roughly 50 per cent less space on site – which can help to reduce leasing costs. On average, the maintenance cost of fuel cells is 77 per cent lower than diesel generators and the operational cost is 37 per cent lower.
Remote monitoring and control
Another major area of expense that mobile operators should look to streamline is their dependence upon network site visits. Currently, experienced technicians must regularly visit each site to configure equipment, perform maintenance and implement repairs. This inefficient use of a technician’s time is often costly, as is the added expense of subsidising their travel. Every site visit expends fuel. The more trips taken, the more fuel burned – which translates to more CO2 produced.
If operators adopt the ability to remotely monitor and control base station functions, they can vastly reduce the need for physical inspections. ‘Soft alarms’ can warn operators when equipment begins to fall below optimum performance – allowing them to choose the best time to respond and thus increasing efficiency by enabling multiple problems to be solved in one visit. Remote monitoring of fuel supplies can also ensure that truck rolls are only made when generators require refuelling – lowering the total number of truck rolls needed per year.
The ability to make remote adjustments, like altering thermostat settings, also completely negates the need for visits to make simple changes to infrastructure settings. For example, the remote tuning of antennas means adjustments can be made as many times as necessary without any additional site visits, or tower climbs to manually change an antenna’s orientation. An added benefit is that adjustable antennas can cover a wider area than their fixed-position counterparts, meaning that fewer antennas need to be installed on a tower.
Technicians also often alter the temperature settings of network sites by many degrees to make it more comfortable to work. This can create significant costs if the thermostat settings are not returned to normal when the technician leaves. If operators are able to monitor the temperature of their sites and remotely adjust thermostat settings, such unnecessary drains on OpEx can be eliminated.
Base station efficiency can be further improved by using remote monitoring software to switch-off non-essential services when traffic is low, ensuring they only consume power as and when it’s needed.
More efficient cooling
The dense electronics within base stations dissipates heat which must be removed in order to ensure the proper functioning of equipment. Given that typical cooling systems consume 30 per cent of the energy used by base stations, they are a clear target for improvements in energy efficiency.
Alternative cooling techniques, such as free-air cooling, economisers and hybrid cooling in enclosures can create significant reductions in both power usage and an operator’s carbon footprint. These techniques can be further optimised through Computational Fluid Dynamics (CFD) analysis and field trial testing.
Such analysis can show that free-air cooling can be sufficient to keep equipment within optimum running temperatures for certain time periods. Analysis demonstrates that air conditioning on-time can be reduced – again lowering power consumption.
Hybrid cooling systems via a direct air/ heat exchanger within enclosures can also reduce base station cooling costs by as much as 85 per cent. Taken together these solutions can reduce overall site power consumption by 20 - 25 per cent.
Mobile operators often install new base stations in areas of poor coverage to improve the service to customers. However, poor coverage is not always a result of lack of network capacity but simply the fact that the radio signal cannot reach a remote location due to lack of transmission power or for geographical reasons, such as a hill or depression in the landscape.
In these instances RF repeaters can boost the radio signal and provide enhanced coverage without the need to deploy additional base stations, operating at approximately half the power required to support an equivalent base station deployment.
More energy efficient equipment on site
Modern telecoms technologies have become far more energy efficient in recent years and by deploying these new technologies, operators can significantly reduce power consumption in their base stations.
For example, high-efficiency power amplifiers can be installed in the final active stage of the radio transmission system, which traditionally operate at a very low efficiency rating with a significant percentage of the applied energy being dissipated as waste in the form of heat, rather than useful RF radiation.
An added benefit of installing energy-efficient power amplifiers is that they minimise the need to remove the waste heat, a process that requires further energy to power air conditioning units or heat exchangers.
Other developments such as remote radio heads, more efficient power rectifiers and smooth walled cabling that provides better attenuation, all demonstrate new architectures that use less power and are ready to be installed on towers today.
With the deployment of smart power grids now on the cards across Europe, mobile operators will have a substantial role to play in supporting wireless communications between smart meters and control hubs.
Smart metering is currently being advocated as one path to improved power efficiency worldwide, and it has been claimed that mobile technology in smart grids could cut Europe’s energy bill by €11.4 billion.
If mobile networks are to truly lead the way in supporting the on-going rollout of smarter European power grids, it’s only fitting that operators look to put their own houses in order first by streamlining their network power generation and consumption with the tools available today.