Although its name and logo invite taking a bite, the heart of the apple may be less sweet than it seems: having a history as the world's most valuable public company and being a model of sustainability at the same time is no easy task.

But international environmental groups such as Greenpeace and the World Wildlife Fund (WWF) have lauded and supported Apple's green actions over the past years.

Among the several initiatives Apple has undertaken to become more environmentally friendly, one recently made headlines: In 2015, Apple recycled a literal ton of gold from its products.

But for a technology company to transition to a fully sustainable model, its entire supply chain has to be developed in an environmentally friendly way. And despite Apple's efforts to reinvent itself as a green company, there is still a lot of work to do.

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Greenpeace classified Apple as the cleanest Internet company in the world in its report: 2015 Click Clean report, which highlighted Apple's commitment to renewable energy.

"Apple has definitely made positive improvements over the last years toward 100 percent renewable energy," Tom Dowdall, a Greenpeace clean energy campaigner, told DW.

According to Apple's 2016 Environmental Responsibility Report, the company is close to running fully from renewables, and has reduced its carbon footprint by 64 percent over the past five years.

Moreover, it has diverted about 45,000 tons (40,000 metric tons) of e-waste from landfills in 2015, from which about 31,000 tons have been reused - including 2,204 pounds (around a ton) of gold.

WWF has partnered with the company to support responsible management of forests in China. It also co-developed the "Apps for Earth" campaign, where proceeds of app sales in Apple's App Store were donated to the group for International Earth Day (April 22) in 2016.

Toward a green apex

Apple has not always had a reputation for sustainability. Five short years ago, in 2011, the company was among the "least green" in a Greenpeace report. According to Dowdall, that was mainly due to reliance on highly polluting coal power, high electricity consumption and a lack of corporate transparency.

Even now that Greenpeace has placed the company at the top of its green list, there are still gaps that need to be filled.

"The greater environmental impact of an electronic device happens at the production stage," Daria Koreniushkina from Fairphone - an enterprise that produces socially and environmentally responsible electronics - told DW.

And this is exactly the main environmental challenge for Apple, Dowdall said. Despite Apple's efforts to help boost solar power in China, its supply chain in the Asiatic country - with 346 supplier facilities - is still far from joining the global renewables trend.

"Suppliers in China have not been included in the Click Clean report," Dowdall said. "Apple still has to work on its supply chain's carbon footprint and renewable energy there."

Indeed, Apple explains in its 2016 report that the electricity used in its supply chain is the biggest source of its carbon footprint - and comprises more than 60 percent of emissions stemming from manufacturing.

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Greenpeace plans to monitor Apple's supply chain from up close, and will try to include the situation in the upcoming report as it develops, Dowdall added.

Long path to sustainability

Public pressure from non-governmental campaigns and from Apple consumers concerned about the environment were among the factors motivating Apple to get greener, Dowdall explained.

Despite demands from consumers, with more than 120 million iPhones already sold in 2016, Apple's growth continues to be difficult to reconcile with the environment.

Koreniushkina believes that designing products considering the environment could be a solution for reducing environmental impacts. "Recycling electronics is not as easy as recycling paper," she said. "So the longer your phone can last, the less environmental impact it has."

Dowdall supports this concept. The only way to have truly sustainable products is through a new business model that closes the loop on the product's life cycle, he said.

How this is supposed to work in terms of profitability for companies like Apple remains to be figured out - particularly in light of flagging revenues. Such a model could work "with products designed to last longer, and offering services instead of new devices," Dowdall said.

"But it's still a long way for tech companies to get there," Dowdall concluded.

And in the meantime, eco-conscious Apple customers can keep calm and carry on. The company assures them: "Whenever you send an iMessage, download a song from iTunes, or ask Siri a question, the energy Apple uses doesn't contribute to climate change."