Base stations eat up a lot of power, accounting for about 80 percent of a network’s total energy consumption. This has prompted operators in developing markets, where electric grids are often either unreliable or nonexistent, to turn to green technology.

China Mobile has thousands of base stations that use solar power, wind energy or fuel cells. Bharti Infratel has deployed 500 solar-powered base stations in India and Cambodian operator Cellcard uses 862 base stations running on solar energy. Operators using green base stations stretch from Africa to Europe, from South America to Mexico.

Still other operators are deploying base stations that use the latest in energy-efficient equipment to cut down on the cost of powering their networks, which the GSM Association (GSMA) estimates can comprise up to 40 percent of network operating expenses in developing markets.

The GSMA, which has compiled statistics on green base stations together with the International Finance Corporation, estimates 639,000 off-grid base stations will roll out in developing markets by 2012. If the GSMA meets its goals, about 20 percent of those base stations will run on solar, wind or biofuels.

Developing nations have emerged as a major growth engine for energy-efficient and green-powered base stations as operators struggle to deploy networks in areas with unreliable or unavailable electric grids.

“As mobile networks spread to parts of the world where there’s no coverage today, very often it means there’s no electric grid,” says Kim Jones, who is part of Nokia Siemens Networks sustainability team. Jones says many operators faced with this conundrum still rely on diesel generators to power their networks, but solar and wind power are gaining market share.

“The problem is that the sun doesn’t always shine and the wind doesn’t always blow. It’s not as easy as saying, ‘Do away with the diesel generator and we’ll install these alternate energy sources,'” Jones says. “What we’ve found is that instead of two large diesel generators, you can go to a small diesel generator as a backup when you don’t have any wind or solar.”

Diesel power still dominates off-grid networks, but improvements in green power sources and the energy efficiency of base stations are helping turn the tide towards renewable fuel. Huawei has helped China Mobile deploy thousands of solar- and wind-powered cell sites throughout rural areas of China, and says demand for the technologies has extended into other developing markets, especially India and Africa.

“We’re seeing an increased interest in alternative sources of energy,” says Madan Jagernauth, Huawei’s vice president of wireless marketing and product management. “There’s a different break-even point now than five years ago for green fuels.”

The GSMA estimates that the annual diesel bill accrued by operators in developing nations will hit $14.6 billion by 2012. Diesel generators continue to be favored over renewable energy sources because they have lower up-front costs. However, they’re often more expensive to run than renewable energy systems, prompting cost-conscious operators to turn to green power.

“If you’re using diesel generators, you have to send someone on a circuit every week to fill those up,” Jagernauth says. “It becomes a very onerous proposition.”

The energy savings and decreased operational expenses of green base stations allow many operators to recoup their investment within two to three years, according to estimates compiled by the GSMA.

Despite the promised cost savings, base stations using renewable energy continue to comprise just a fraction of network deployments.

Ken Wirth, president of 4G/LTE at Alcatel-Lucent, says diesel generators continue to attract operators because of their lower short-term costs. Wirth says the number of green base stations currently in deployment are “very small” but believes the technology will become more widely adopted as renewable energy sources become cheaper and network equipment becomes more energy efficient.

Developed Markets See Green Differently

Operators in developed markets like the United States and Europe rely on the electric grid to power their wireless networks, but that doesn’t mean they’re missing out on the green game.

Infrastructure companies say they’re using equipment with vastly improved levels of energy efficiency in all aspects of the network, from its basic architecture to the individual components used in their cell towers.

The 4G networks being deployed around the world are inherently more energy efficient than their predecessors, and even the equipment that’s being used to upgrade 3G networks has come a long way over the past few years.

One of a base station’s main energy drains is the power amplifier, which consumes about 70 percent of a base station’s power, according to estimates from the Alliance for Telecommunications Industry Solutions (ATIS).

Power amplifiers used in early wireless deployments were notoriously inefficient. For instance, an amplifier in early deployments would have an efficiency ratio of about 5 percent, meaning it would have to consume 100 Watts of electricity to transmit 5 Watts of signal. Now, vendors are boasting power amplifiers with efficiency ratios hovering around 40 percent.

Oliver Blume, a senior research engineer at Alcatel-Lucent’s Bell Labs, says power amplifiers could boast efficiency ratios of 60 percent or even 70 percent as a result of more complex amplifier architectures such as Doherty architecture, envelope tracking power amplifiers and amplifiers that make use of digital rather than analog amplification.

Blume says there’s little benefit to driving efficiency ratios much above 70 percent, since the incremental cost of advanced power amplifiers will outweigh the savings achieved through efficiency gains.

Heating and cooling is another driver of energy consumption in base stations. Some newer base station models don’t require additional heating or cooling. Nokia Siemens Networks’ flagship Flexi base station is a hallmark example of energy efficiency, since the ultra-lightweight piece of equipment doesn’t require air conditioning or heating, even in extreme environments.

The Flexi consumes 70 percent less power than conventional cabinet-based base stations and has been successfully deployed in a variety of environmental conditions, from heat-ravaged regions in the Middle East to the frigid temperatures of Scandinavia. Nokia Siemens says it has deployed more than 100,000 LTE-ready Flexi base stations around the world.

In addition to improvements in power-hungry network equipment, the basic architecture of next-generation networks is changing to optimize both performance and energy efficiency, while network management tools like dynamic powering reduce electricity consumption without major equipment upgrades.

Many operators deploying 4G networks are employing macrocells and picocells to shore up coverage and capacity. These smaller cells consume far less energy than a base station and allow operators to offer increased levels of service without a parallel increase in electricity consumption.

In-Stat principal analyst Allan Nogee says smaller cell deployments can operate at a lower power because they don’t have to cover a large area like a large base station would.

While these types of deployments are typical in 4G deployments, legacy 2G and 3G networks are not as energy efficient and it could be some time before operators decide to replace the equipment.

“It’s going to be many years before we transition to smaller cells, but it’s happening over time,” Nogee says. Nogee sees the shift towards energy-efficient equipment being driven not by the halo effect of green technology, but by cost considerations.

“Operators are going to do something if it’s cheaper,” he says, referencing green base station deployments in off-grid areas. “They’re not really motivated by conserving. It all comes down to what’s cheapest.”

Some operators are moving towards green technology out of necessity; some are using the equipment to reduce costs. No matter the motivation, networks around the world are becoming more energy efficient. Whether operators are deploying base stations running on solar power or employing more energy-efficient power amplifiers, wireless networks in both developed and developing markets are on their way to being green.