Do towercos need to create their own minigrids?

What can we do about cell site power demands increasing? Cell site power clustering is one option, but efficiency drives and proper site dimensioning have a role too

Read this article to learn:

  • What is increasing power on cell sites?
  • How to dimension cell sites properly
  • What is the role of renewables in MENA?
  • Solutions for reducing power load
  • What is site clustering and where is it relevant?

Participants in TowerXchange’s Greening the Network and cell site energy sessions at TowerXchange Meetup MENA identified at least several trends driving up power demand on cell sites. Luckily the industry has some ready to go solutions which it must deploy. In many ways, MNOs and towercos are the victim of their own success, as advances in mobile adoption and increases in data consumption drive increases in site power consumption, and it is down to the industry to resolve these complex issues. Below you will read about what is increasing site power and what to do about it.

What is increasing power on cell sites?

Increasing tenancies are pushing up power demand. As towercos have become more prevalent, sites which were once home to one MNO’s equipment now host the equipment of two or three operators. While some equipment can be shared, each new tenant adds significantly to the power demands for that site. This is more efficient than running parallel infrastructure, but it makes the variance in power demand from site to site much larger, making planning more complex.

Technology upgrades are also boosting power demands. While 3G is more efficient per byte of data than 2G, as is 4G versus 3G, or 5G versus 4G, the actual practical effect of technology upgrades has been to increase power demand as new technologies enable greater and greater use of data.

In some markets, MNOs have retired older 2G and 3G infrastructure, significantly lessening the power load on sites, but in many markets, towers must carry equipment for 2G, 3G, 4G and soon 5G. And because of increasing tenancies a towerco can be running multiple technologies for multiple operators. Some newer technology can run multiple Gs at once, but most legacy systems cannot.

Traffic is also increasing across networks, which is prompting a response from MNOs to improve capacity and maintain quality of service. That results in MNOs adding additional sectors or more active equipment which also pushes up power loads to ensure 3G or 4G networks perform as expected by consumers. Bladon’s Stuart Kelly discussed his experience in South Africa where single tenant sites originally dimensioned for 1-2kW outgrew their original design because local economic activity gravitated closer to the tower. Simple solutions which can respond flexibly to increasing power demand are essential.

As sites become more complicated, you also have legacy layouts which are underperforming. When power demand was low, less efficient rectifiers or “good enough” electrical engineering could be excused, but now sites need optimum layouts to avoid needing to much power. One particularly bad example cited was of a site in which a DC generator fed power into an AC converter which fed into a rectifier to supply DC power to the system. Most sites are not as badly engineered as that, but site audit is very important to identify inefficiencies.

Compounding the problem are cooling systems. As power demands increase so do cooling demands which again require power to run. As Aubren’s Walid Saleh highlighted, inefficient systems which require lots of cooling compound the problem, requiring an oversized cooling solution. Outdoorisation and other alternatives can keep the power required for cooling to a minimum, but it is still better to not generate the heat in the first place to create a win-win situation.

A few years ago, a two tenant site in Africa would require just 3-4kW to run satisfactorily, but now basic sites regularly require 5-6kW and a popular site carrying multiple technologies can draw multiples of that.

Dimensioning sites is getting harder

Because of the multiple factors which can affect site power demands it is becoming increasingly complex to dimension a new site correctly, particularly where grid power is unreliable. Dimensioning is the process of calculating the appropriate power equipment for a site given its characteristics. Any towerco wants to lease up a site rapidly (and increase the power demand on the site), but to install all the equipment necessary to run a multi-tenant multi-technology site from day one would require a major capital outlay. Ensuring sufficient space for expansion and modularity in design are hence vital for dimensioning a site currently.

In Africa, sites are usually dimensioned with energy systems to cater for loads up to 3kW, this enables sites to expand to carry two tenancies while only using 70-80% of total capacity to retain some flexibility and resilience. However, as described above, power demands on sites are increasing rapidly and such rules of thumb will likely soon be out of date. Dimensioning plans which made sense one year ago, can be rendered inadequate if one or more MNO accelerates plans to rollout LTE, for example, as Airtel Africa have done over the last couple of years.

Physical size also plays a major role in dimensioning sites. An on-grid site can benefit from a small battery bank which can be relied on to provide short-term back-up power. Size becomes an issue for a site which relies on its own primary power. If you want to cycle batteries you need to find space for your generators and batteries. If you want a combined solar hybrid system then you will also need space for solar panels. As site energy demand goes up so does the floor space required for solar panels and for the batteries to store energy when the sun is out.

There are also sites which must be kept active where refuelling is impossible. SerEnergy’s Esben Overgaard remarked during our discussion that at times they have to keep sites online for 6-8 weeks during monsoon season where refuelling is impossible and local grid power unreliable. That requires local fuel tanks for the fuel cell’s water-methanol fuel source and an energy set-up which is very different to sites which may only have 6-8 hours of grid downtime at a time.

But oversizing is not a solution. Ultimately, towercos cannot assume that the multiple inefficiencies pushing site power higher will continue indefinitely. Legacy network equipment is getting swapped out and new sites are being built with new efficient equipment which radically cuts power demands. Similarly, not all generations of equipment will be required for the long-term as some older tech is turned off or replaced with shareable alternatives. While basic sites may be required to be dimensioned at a higher 3-4kW level in the medium term, attention should turn to the many ways site load can be reduced or power generation made more efficient.

Solution to reduce power load

Towercos and MNOs have many strategies available to reduce power load on sites, for example, new network technologies from the major OEMs and OpenRAN competitors are able to run multiple generations from one base station, allowing 2G and 3G connectivity to be provided at 150Ws of power. This has enabled firms like Africa Mobile Network to rollout low-cost rural sites which rely solely on solar and storage.

Sharing can also extend beyond steel and grass or generating equipment. All elements of the power set-up can be shared, but towercos can also start sharing equipment like antennas to reduce extraneous equipment. In Poland Cellnex is taking control of the RAN for Polkomtel, showing the potential for an enhanced towerco model to further increase efficiency. This reduction in duplication goes to the heart of the towerco model and is being explored more aggressively with MNOs that want to cut their own costs too. Using the correct control systems and ensuring rectifiers are working efficiently was also highlighted.

Henrik Sundh of Enersys highlighted the role of modular and expandable systems in helping manage site power. Battery technology which suits sites at their current load, but which can be expanded offers a great way to balance space and power requirements. Peak shaving and cycling with generators can be scaled relatively straightforwardly for most sites.

The role of renewables in MENA

The Middle East is a region blessed with abundant energy. Oil and gas are the most famous, but the region is amongst the best for solar irradiation and wind resource too. There is, however, a battle between economics and environment and while distributed solar PV and wind turbines have seen their costs slashed in recent years, grid power and diesel remain extremely competitive in the Middle East.

In some global markets, diesel is taxed aggressively and is being phased out, in many MENA markets diesel is subsidised. This makes the high capex/low opex model of much renewable energy uncompetitive. This makes a focus on reducing site power all the more important if MNOs in MENA are to contribute to decarbonisation.

Grid power decarbonisation should be driven at the government level, but MNOs can make a material difference to their emissions and bottom lines by making their sites more efficient. Selling sites to towercos, as is increasingly the trend in the region, is probably the best way to realise these benefits as where towercos are managing power they are better incentivised to remove inefficiencies as outlined above.

Site clustering and mini-grids

At TowerXchange Meetup MENA, IHS Towers’ Bachir Estephan discussed a strategy of site clustering which was being explored. This would involve combining the power generation for multiple sites in a central location to solve many of the problems of growing demand.

There is precedent for this in Myanmar and Australia. In Myanmar there are many minigrid providers serving local areas which see a towerco’s site or sites as high quality anchor tenants, as highlighted by Apollo Towers’ Aashish Khadsare. In Australia too, Bladon’s Stuart Kelly highlighted the similarities to Africa with vast areas which are economically important but far from population centres. There, some mines run their own private telecom networks which are often powered from a local grid. In Africa, however, there is no history of clustering sites or the powering of a local network by a local minigrid.

IHS Towers have identified situations where the increased complications of running a small power plant and dealing with local distribution networks (or creating their own) are more than balanced out by the improvement in site performance possible and the increased tenancies and technologies they can service on their towers. These are densely populated areas where site space is constrained but where telecom demand is robust; areas within a 2-3km radius where distribution to 5-15 sites is manageable.

This would turn the problem of site power on its head, rather than worrying about how to squeeze in 15kW of power generation for the hungriest sites you can start at square one and build a small efficient power plant. This would allow for increased use of solar power, better dimensioning of batteries and more efficient use of generators (which are not best suited to the typical 3kW load of a cell site in any case).

The solution follows from the situation. In Africa, demand for telecoms infrastructure is outstripping the ability of states to provide supporting infrastructure like power grids. Site clustering is one answer and may become a key tool if 5G is launched and pushes up power demands even higher.

Alternatively, as in Myanmar, towercos could become anchor tenants for minigrids that are developing. Minigrids reliant on solar power are a good fit for Africa where usable land can often be found adjacent to densely populated land, solar irradiation is good, and there is a desire to wean the continent off long-term reliance on diesel generators.

The power demands of cell sites are changing all the time, but we are in for a sustained period of increasing power demands, especially as 5G is rolled out faster than old networks are turned off. Where possible renewable generation should help decarbonise power, but the lowest hanging fruit are from using the power generated more efficiently.

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