To study the behavior of wild animals, scientists routinely tag them with GPS location trackers. But such devices' battery capacity limits how long they operate, often bringing an early end to significant conservation work. Solar-powered trackers are also a poor choice for they break easily and don't work for night creatures.

So biologist Rasmus W. H. of the University of Copenhagen and his colleagues turned to another abundant power source. After some trial and error, they finally came up with a tiny generator powered by a pendulum (摆锤) inside a closed device. As the tagged animal moves, the swinging pendulum forces a ring to slide across a copper coil, generating current which is then used to power the sensors for GPS unit. The tracker, which could theoretically survive for the entire life span of an active animal, was recently tested on domestic dogs, a wild pony and a European bison. The dogs and bison in the study were active enough to create the energy for one GPS transmission cycle per day for 14 days and 17 days, respectively. One of the wild pony's-trackers lasted at least 146 days but didn't produce enough power for daily transmissions, the researchers reported in Plos One.

The limited power generated by the animals' movements means the new tracker isn't ready for prime time just yet, says ecologist Emily Studd of British Columbia's Thompson Rivers University, who wasn't involved in the study. When researchers want to keep close track of animals, they often need GPS fixes more than once a day. But Studd says that with a bit more development, this could be a game changer for wild-life animal research and monitoring.

Rasmus and his colleagues hope conservation workers can one day use this technology to track species such as tigers, leopards and wolves, which can easily destroy solar-powered trackers and which hunt and travel at night.

Lego is considering a brick rental scheme in an attempt to cut down on plastic waste. The Danish toymaker has promised to make all its bricks from sustainable sources by 2030 and is searching significant resources into finding alternatives.

Tim Brooks, vice-president responsible for sustainability, said the company was "totally open" to the idea of a product rental scheme but acknowledged that lost pieces could be a significant problem. He said the rental scheme was "possible" but admitted there were some "technical barriers", one of which is the complexity of some Lego sets, many of which contain thousands of pieces. "What are the chances of giving them to an eight-year-old child and getting them all back again?" Mr. Brooks added.

Lego has come under increasing pressure to reduce its carbon footprint with growing international alarm about the impact of plastic waste on the environment. Lego reportedly gives off around a million tons of carbon dioxide each year, with about three-quarters coming from raw materials that go into factories. It produces 19 billion pieces per year -36, 000 a minute - that are made of plastic and much of the inner packaging is also plastic.

So far, the only breakthrough has been the development of a line of bricks made from plant-based plastic sourced from sugarcane(甘蔗). The green trees, plants and flowers were first included in Lego sets late last year but account for only one-two percent of the total amount of plastic elements produced.

Henrik Ostergaard Nielson, a production administrator in Lego's factory, told the New York Times last year, "We need to learn again how to do this. " The company has invested more than €100, 000, 000and hired 100 people to research non-plastic alternatives. It is aiming to keep all of its packaging reusable by 2025.

Extended producer responsibility (EPR) refers to a policy approach where producers are given responsibility for the environmental impacts of their products throughout the product lifecycle. Based on the polluter pays principle, this approach requires producers to finance the costs of recycling or disposing of products that consumers no longer want. It aims to shift the costs associated with the management of dealing with solid waste away from the local government.

The term EPR was first coined in 1990 by a Swedish professor, Thomas Lindhqvist, who introduced the idea of producers being responsible for their products to the Swedish Ministry of the Environment. The first example of EPR came in Germany in 1991, where manufacturers picked up household packaging alongside municipal waste collections. Since 1990, countries around the world have adopted EPR policies around key sectors such as packaging, electronics, batteries, and vehicles.

EPR creates a financial motivation for producers to design products that last longer and can be recycled. This is because EPR places the end-of-life costs on the producer. EPR has historically been successful in the managing of products that pose risks to communities such as batteries, paint and old medicines. EPR has led many producers to redesign these items to reduce their risks. Finally, due to ERP closing the loop (循环) on materials management, this approach uses much less energy than it takes to produce items from the beginning.

However, critics of EPR have issues with producers adding recycling costs to the initial price tag of a product. Another disadvantage is that at the international level, it can negatively affect imports to countries that have strict EPR policies as producers in other countries will not want to be subject to extra fees from these policies. Additionally, it restricts competition at the local level as producers who take on the extra costs to accommodate EPR policies are at a competitive disadvantage to those who are able to bend the rules and get out of paying these costs.