EarthTalk® | February 2020

Researchers at the University of Oxford in the UK are experimenting with perovskites as the semiconductor in these small tin solar cells that could someday be on your rooftop supplying your home with free electricity. Credit: University of Oxford Press Office FlickrCC.

Dear EarthTalk: What is perovskite-based solar all about, and how does it differ from silicon-based solar? — Mary W., Baltimore, MD

No doubt, solar power has been growing rapidly, with a 28-fold increase since 2009. This expansion has been driven mainly by a massive reduction in the cost per kilowatt of solar-generated electricity. In many regions, it’s more economical to set up solar arrays than it is to create a new coal or natural gas plant. But how much further can we really take solar given that we’re already maxing out the efficiency of our panels and many regions of the world are still too dark to take advantage of them accordingly?

One answer might be perovskites. This calcium titanium oxide crystal found in the Earth’s mantle can be used instead of silicon as a semiconductor, driving the capture and transmission of energy from solar rays to electricity. There are many different types of perovskites, but they all share the same general molecular structure. Recently, materials scientists have been working on ways to harness their unique electrical and photovoltaic properties to boost the efficiency of solar collection. They see this as an imperative, given that our current crop of silicon-based panels top out at only 20 percent efficiency in ideal conditions, and that’s after decades of research and development to optimize them.

In 2009 when research in perovskite-based solar was just beginning, panels made with the crystal showed efficiencies of around 4 percent. By 2018, researchers boosted this number to 24 percent. No other type of solar technology has seen an efficiency jump of this magnitude in such a short amount of time.

Several other properties add to the appeal of perovskite-based solar cells. They are relatively easy and cheap to produce, and are suitable for use in applications that silicon-based panels aren’t. Perhaps most importantly, they can generate electricity using wavelengths of light that most of our current commercially available panels can’t harness. Researchers envision a future where perovskite panels are actually fused into a layer on top of traditional silicon panels. In this tandem application, perovskite panels would capture part of the incoming light while the rest shines through for the silicon panels below.

Despite the promise of perovskites, there are still many hurdles to overcome before they can become a viable large-scale option. One is lifespan: Silicon-based panels last between 25 and 30 years, while perovskite versions created in the lab only last a year at most. Another issue is scalability. The high efficiencies in perovskite cells that scientists have observed have only been achieved on very small (“postage stamp” sized) panels. On larger perovskite panels, the efficiencies have been much lower. The final big obstacle for perovskite researchers to overcome is toxicity. At the moment, high-efficiency perovskite cells can only be made using relatively toxic compounds, such as lead. While less toxic versions exist, they are also less efficient.

Daunting though these challenges may be, many bright minds are working to solve them. While solar power’s future is by no means certain, it is looking increasingly like this powerful little crystal will play a major role in bringing sun-derived energy into the mainstream market.

Contacts: Worldwide Renewable Energy Forecast 2019,; Rise in Perovskite Research 2011-2015, .

These Rainforest Alliance Certified coffee plants are grown under natural shade created by native tree species on this Guatemalan coffee farm. Credit: Charlie Watson, FlickrCC.
Dear EarthTalk: There are so many eco-labels out there these days. How can I tell which ones are valid and not just “greenwashing?” — Penny Rasmussen, Calumet, MN

With countless products now available labelled as “eco-friendly,” “safe for the environment” or “organic,” it’s hard to know which ones are actually good for the planet. Many are legitimate, but lots of others feature deceptive or unsubstantiated claims. And even the legitimate labels vary a lot in meaning. Truly valid eco-labels are awarded by independent third parties, not the companies who sell products on which they’re featured. These days many companies are placing misleading claims and nonsense labels on their products to create the illusion of environmental friendliness, a practice known as “greenwashing.”

Third parties, on the other hand, require products meet certain specific criteria before granting the right to display their eco-label. When we know they are trustworthy, eco-labels can serve as a potent means for altering consumer behavior in a way that benefits the environment.

There are some common eco-labels that we can vouch for given decades of trustworthy certifications. The U.S. government’s Energy Star label identifies products, devices and appliances that meet stringent energy efficiency standards. If you buy an Energy Star certified dishwasher, you know you’re saving energy (and money) versus other models that don’t qualify.

Another trustworthy eco-label seen often on coffee, fruits, tea, paper or furniture is “Rainforest Alliance Certified,” a designation for foods and building materials sustainably sourced from tropical rainforests. The non-profit Rainforest Alliance runs this program in part by vetting producers throughout the tropics.

If you like to know the products you buy are sourced sustainably by workers who were not exploited and were paid a living wage, look for the “Fair Trade Certified” label. Almost a million workers across 45 different countries currently benefit from the sourcing or production of Fair Trade items.

Meanwhile, the “Certified Organic” label signifies that a food contains at least 95 percent organic ingredients. Plant-based foods bearing this label have not been treated with petroleum-based fertilizers or conventional pesticides, and have not been genetically modified. You can rest assured that any “Certified Organic” animal products you consume have not been treated with antibiotics or growth hormones and were fed organic feed and allowed access to the outdoors. And any products labeled “Made with Organic Ingredients” contain at least 70 percent organic ingredients.

Some other trustworthy labels include: LEED, GreenSeal, FSC-Certified, Salmon-Safe, WaterSense and Non-GMO Project Verified. If the label in question isn’t mentioned above, it might be worth investigating. Sharing what you know about eco-labels, whether by word-of-mouth or via social networks, is a fantastic way of helping the environment. As awareness grows, those you have enlightened will be able to exert an ever-greater positive force upon the market.

Contacts: Energy Star,; Rainforest Alliance,; Fair Trade Certified,; USDA Certified Organic,; LEED,; Green Seal,; Forest Stewardship Council,; Salmon-Safe,; WaterSense,; Non-GMO Project Verified,

The #BreakFreeFromPlastic movement is one of many campaigns designed to convince people to opt for healthier, greener alternatives to plastic. Credit: Zelena Akcij, FlickrCC.
Dear EarthTalk: Which companies are taking the lead in commitments to plastics reduction?— Jason K., Reno, NV

Our modern world is literally swimming in plastic. According to Plastic Oceans International (POI), we produce over 300 million tons of plastic each year around the world, half of which is for single-use purposes. We then dump eight million tons of it into the oceans annually, where it accumulates up and down the food chain, with some settling into large, mid-ocean whirlpools of plastic waste called gyres.

Since the 1950s, we’ve produced upwards of 8.3 billion tons of plastic, and production is seemingly only just starting to ramp up: A recent study predicts we’re on course to add another 26 billion tons to the planet’s existing plastic burden by 2050 if production remains unchecked.

Weaning ourselves off plastic is going to be one of the great challenges of the 2020s. Consumer demand, along with governmental action, is forcing many companies to re-examine their manufacturing processes, supply chains and distribution networks to reduce the use of plastic in both products and packaging.

One leader is Ikea, which recently committed to transition much of its plastic packaging to a mushroom-based renewable alternative that can grow in a controlled environment, and, like plastic, be easily formed into shapes. If kept dry, this “MycoComposite” can be used over and over. It can also decompose fully in just 30 days. Producing it uses only 12 percent of the energy required to make the same amount of plastic, and with 90 percent lower carbon emissions.

Another step in the right direction is Mattel’s recent commitment to use 100 percent recycled, recyclable or bio-based plastics materials in both its products and packaging by 2030. Early in 2020 the company will debut its first product aligned with this new goal, the Fisher-Price Rock-a-Stack, made from sugarcane-based plastics and packaged in 100 percent recycled or sustainably sourced material.

Walmart announced in February that it seeks to achieve 100 percent recyclable, reusable or compostable packaging for its private brand packaging by 2025 and will encourage other brands it sells to set similar goals. The retailing behemoth is also working with suppliers to eliminate non-recyclable PVC plastic in general merchandise packaging altogether by 2020.

These efforts are laudable, but some worry that shifting to alternatives doesn’t fully address the problem: Due to public concerns about plastic pollution, says Greenpeace’s Graham Forbes, “we are witnessing a parade of corporations scrambling to look greener” by advancing false solutions that don’t address our addiction to single-use packaging. Instead, Greenpeace argues, we need to get away from throwaways and refill our own containers. We’ll only see real change, says Forbes, when we prioritize re-use.

Contacts: POI,; “Production, use, and fate of all plastics ever made,”; Ikea: A Sustainable Everyday,; Mattel Citizenship,; Walmart Sustainability Index,; Greenpeace,; #BreakFreeFromPlastic,

He’s not everyone’s cup of tea, but media mogul and former NYC mayor Michael Bloomberg could be the greenest president to date — if he can win the Democratic nomination and then unseat Donald Trump in the general election. Credit: Azi Paybarah, FlickrCC.
Dear EarthTalk: Where do the remaining Democratic presidential candidates stand on climate and environment? — Mary W., Miami, FL

It was just a few months ago that two dozen Democrats were vying for their party’s nomination to take on Donald Trump in 2020. While technically 16 are still in the race, only seven — Biden, Buttigieg, Klobuchar, Sanders, Steyer, Warren and Yang — qualified for participation in the December 2019 debate (based on a minimum number of contributing supporters and success in polling in the four “early voting” states). While the Democratic party will most likely choose its candidate from among these seven, it’s still too early to count out the other contenders.

For their part, environmentalists would’ve been happy if Washington governor Jay Inslee, who made promoting the need to address climate change the central tenet of his 2020 presidential bid, was still in the race. Before dropping out in August, Inslee released an omnibus plan to phase out fossil fuels and shift the economy wholesale over to green energy. Fans called it a more practical version of the Green New Deal, a similarly comprehensive green energy-based economic overhaul plan introduced into Congress earlier in the year.

With Inslee out, no one candidate stands out as particularly focused on the environment, although they all support a carbon drawdown of some sort. Elizabeth Warren has adopted Inslee’s climate plan lock, stock and barrel. Previously, she had co-sponsored the Green New Deal along with fellow senators Sanders, Booker and Klobuchar. Most of the other Dems in the running expressed support for the Green New Deal.

Meanwhile, Tom Steyer, a hedge fund billionaire-turned-activist, has lots of environmental cred given his role as founder and funder of NextGen Climate (now NextGen America) an advocacy non-profit and political action committee which steered some $74 million of his riches toward environment-friendly Congressional and gubernatorial candidates in the 2014 elections.

Another compelling candidate from an environmental perspective is media mogul and former NYC mayor Michael Bloomberg, who has put up $150 million of his own money in support of the Sierra Club’s “Beyond Coal” campaign which helped shutter some 50 coal-fired power plants nationwide. Last June, he pledged another $350 million to the cause via Beyond Carbon, his initiative to fight dirty energy.

Other candidates may not have as much money to throw around, but it doesn’t mean they aren’t also keen to fight climate change. Reading through the answers of a recent environment survey of the Democratic hopefuls by the non-profit League of Conservation Voters shows more similarities than differences, with each of the Dems pledging to commit billions or trillions of dollars to fighting climate change and restore the U.S. to a leadership position on the issue internationally.

In short, voters concerned about climate change would do well to pull their levers in favor of any of the Democrats running. Whether there are enough like-minded Americans to unseat Trump in 2020 is another question entirely — but the health of the planet may just hang in the balance.

Contacts: League of Conservation Voters,; NextGen America,; Sierra Club’s Beyond Coal,; Bloomberg Philanthropies’ Beyond Carbon,

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