Energy


are most cost-efficient when properly dimen- sioned and intelligently managed with opera- tional cost in mind. Automatic on/off cycling of the generator helps save cost, but may not ensure optimal maintenance cycles, maximum battery life and efficiency, or account for the position of the sun. Smart hybrid solutions factor in these and other energy, load and site considerations to determine the most suitable generator size, alter- nator profile, fuel source, security measures, etc.


Fuel cells Small fuel cells typically powered by hydrogen are an option from an environmental point of view, and various solutions have been deployed successfully to extend standby operation. Te challenge to successful implementation and op- erational management is the fuel supply chain. In order to be prepared for unforeseen events such as hurricanes, ice storms and power outages, emergency plans must be established to ensure that fuel is readily available and technicians and procedures are in place to service sites.


Battery power With the advent of green grid initiatives and elec- tric vehicles, new cyclic battery technologies and management units are rapidly emerging. Tese advanced batteries are ideal for hybrid applica- tions where energy can be frequently cycled or stored and released in off-grid or grid-independ- ent solutions. Once grid dependency is removed, batteries become the critical foundation of a reli- able hybrid solution. More than any other element, active battery


management will ensure long service life, mini- mal site cost and maximum uptime.


Solar energy Proper use of solar power begins with under- standing solar intensity and seasonal variances in order to design sites for their unique physical conditions. Te most effective applications are in areas where annual solar radiation levels are greater than 1·101kW per square metre per year, as in central or southern Europe, though effective solutions are still possible further north. In addition to solar radiation levels, some prac-


tical considerations also need to be addressed. So- lar is a low-density energy source, delivering less than 150 W/m². In commercial environments where the time-window to collect and store en- ergy is limited, effective site planning is the key: • allocate the space and clearance for solar panels and associated mounting;


• provide an unobstructed view of the Sun; • incorporate a landscape management plan that accounts for shadows today and in ten years;


• consider other regional or local demands, such as the ease of shedding snow. Security and periodic maintenance also must be considered – protecting panels from theft, and


LAND mobile September 2012


Onshore wind map of Europe: the contours indicate wind power at 50 metres above ground level. © DTU Wind Energy, formerly Risø National Laboratory, Denmark


sub-optimal operation due to dirt is important. A smart hybrid system, actively managed, can minimize cost by dispatching service personnel only when cleaning or repair is necessary. Tough the Sun always rises, solar energy is still a variable energy source.


Wind energy Wind is best in an array of turbines for large pow- er delivery connected to a reliable electric grid. Te scale of the utility turbines with multi-point deployment allows for cost-effective manage- ment of maintenance and wind variability. Te use of wind turbines at a cell site needs to account for community acceptance, for the ability to run unattended under all conditions, and for the in- evitable windless days. As with solar, resources are available to provide


regional assessments of the viability of wind. If interested in employing wind energy, look for lo- cations where the average wind speed is greater than 6 m/s and the site provides a clear unob- structed path for the incoming wind. In select- ing a solution, note that financial incentives or rebates may exist. Often it is better to place a wind turbine on


the AC utility side (net metering or feed-in tariff) than directly on the telecom DC bus.


For a single-point, off-grid cell site, effective


use of wind as a power source can be a challenge – for cost or energy – but it can be successful in some locations.


Systemsolutions Hybrid has become a generic marketing term to describe many applications and products, but for telecom, a good hybrid solution is a system that manages and effectively balances multiple energy units, delivering best cost. Ultimately, all sites are different and will require innovative solutions and engineering. With suitable research and planning, there


are hybrid options that can fit urban or remote network sites, and help telecom providers balance their capital expense while reducing their op- erational costs. And with active management of smart hybrid systems, providers can ensure that not only have they installed the best solution, but that they will continue to reap additional opera- tional savings as their network rapidly evolves.


• For fuller information, a White Paper entitled ‘Hybrid Energy Deployment: what to con- sider when enabling alternative energy sources at the cell site’, can be downloaded from www.emersonnetworkpower.eu/EnergySystems


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