Rooftop Solar and EVs Save Water and Cut Pollution: Better Use of Data Will Optimize the Benefits
By Beia Spiller
Thanks to improvements in technology, it's easier than ever to be green.
Solar panels and electric vehicles (EVs) are two prime examples of technologies that can help people minimize their environmental footprint, without sacrificing comfort or having to radically change their daily behavior. But the question still remains: How much of an environmental benefit do these technologies actually produce? And, are there actions that owners of these technologies can take to minimize their pollution footprint even more?
A new paper by my colleagues and me, recently published in Energy Economics, attempts to answer these two questions for households in Austin, Texas. These homes are part of Pecan Street Inc., a living smart-grid laboratory with the largest customer energy-use database on the planet. Using detailed household-level data from 2013-2015, we were able to track solar panel performance and EV use and charging patterns, and match these actions to two important environmental impacts: water use and greenhouse gas (GHG) emissions.
Our paper confirms that, in Texas, using residential solar panels consumes less water and pollutes the air less than using the central-grid power (based on its electricity sources during those years), and driving an EV instead of a gasoline vehicle generally reduces the household's water and emission footprint, even though EVs charge from the grid. Moreover, our analysis demonstrates how carefully examining energy-use data can help us make sure we're maximizing clean energy's benefits.
People may know that burning fossil fuels—whether to create electricity or drive gasoline vehicles—emits gases that pollute the air. But you may ask, how do the central electric grid and cars use water?
Water is used to produce many forms of energy, including both fossil-fuel based electricity and gasoline. For electricity generation in a natural gas or coal plant, large quantities of water are used for process-related needs, as well as to cool the power plant. The production and refinement of gasoline also uses a lot of water; in fact, we calculate that it takes about four gallons of water to produce one gallon of gasoline.
Wind and solar PV, on the other hand, need virtually no water to create power, and they do not emit GHGs or other pollutants in the process.
The solar findings
Because solar panels consume no water and emit no pollution, installing a solar panel allows a household to reduce both the water use and air pollution associated with grid electricity.
In fact, we find that solar panels in Texas have a very large and positive impact on both water and GHG emissions, reducing a household's combined footprint by about 75 percent (a previous Pecan Street study also found solar panels reduce homes' water-intensity by approximately 79 percent).
In Texas during the day when the sun shines, the main power sources are natural gas and coal. So, if you're getting some or all of your power from your own solar panels, you're avoiding using that high-GHG emitting, thirsty electricity from the grid.
Importantly, we find that a household can improve its environmental footprint even further by facing its solar panels south, capturing more sun throughout the day. However, this can conflict with local electric system attempts to maximize production during periods of peak demand, generally in the afternoon when people are getting home from school and work. For example, Pecan Street provided subsidies for solar owners in their community who face their panels west, thereby generating more electricity during that afternoon period, but less overall over the course of the day. Less electricity from the solar panels overall means more water use and emissions from the central grid.
This contradiction highlights the importance of analyzing data. A better understanding of hourly energy usage and emissions can inform electric system policies and pricing that lead to a reduction in total costs, including those related to the environment.
The EV findings
Understanding electric vehicles' environmental impact by these measurements is a bit trickier, because EVs avoid gasoline (thereby reducing water use and GHGs), but they also charge using the grid, which in Texas is largely powered by fossil fuels (thereby increasing both water use and GHG emissions).
Our paper therefore tested whether, on net, EVs are good for the environment—in this case by reducing water use and GHGs—in Texas.
To be able to quantify the environmental benefits of EVs, we needed to think about what vehicle the household would have driven had it not purchased an EV. Vehicle owners have many choices in the marketplace, and fuel efficiency is not the only deciding factor. For example, a family with many children or someone who needs to haul a trailer may not be willing to trade off vehicle size or horsepower in favor of a more compact EV. On the other hand, a person who likes small cars may place greater weight on fuel efficiency; this person's alternative to an EV is more likely to be a hybrid, whereas the large family's alternative vehicle is more likely to be a minivan.
Understanding what the alternative choice would have been is key in measuring the environmental impact of an EV: the less fuel-efficient the alternative vehicle, the better the EV is for the environment. For example, if you switch from driving a gas-guzzler to an EV, that's more beneficial than someone switching from a hybrid. In fact, we find that if the household's alternative-choice vehicle is a hybrid, using an EV can actually increase its net water use—the reduction in gasoline use is very small due to the high efficiency of the hybrid, and the EV is charged with thirsty grid electricity.
That said, we find that EVs always reduce GHG emissions, on net, regardless of the alternative vehicle. Although the benefits do vary largely with the efficiency of the alternative vehicle, they would always increase the cleaner the grid becomes.
Our findings related to EVs suggest three distinct policy solutions:
- Ensure that vehicles such as SUVs and trucks have electric offerings, which manufacturers like Tesla and Volvo are already working on. This will help steer those who require larger sized vehicles towards choosing an electric option, thereby drastically reducing their environmental footprint.
- When people purchase a new EV, a well-designed rebate program that pays them to surrender their inefficient vehicle to be destroyed (such as an improved "Cash-for-Clunkers" program from 2009) could lead to even greater reductions in the environmental impacts of driving.
- Ensure more grid electricity comes from solar and wind, thereby further improving the water- and emission-intensity of EVs. Especially as EV adoption increases, having a clean grid will help us achieve a more environmentally-friendly transportation sector.
Solar panels and electric vehicles will help pave the way to a cleaner future, but we must dig into the details to ensure we maximize the environmental benefits. The more data we have and examine, the better that decision-makers can design energy programs and incentives to improve our environmental footprint.
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The Washington Redskins will retire their controversial name and logo, the National Football League (NFL) team announced Monday.
By Alyssa Murdoch, Chrystal Mantyka-Pringle and Sapna Sharma
Summer has finally arrived in the northern reaches of Canada and Alaska, liberating hundreds of thousands of northern stream fish from their wintering habitats.
A Good News Story?<p>On the surface, the <a href="https://doi.org/10.1111/fwb.13569" target="_blank">results from our study</a> appear to provide a "good news" story. Warming temperatures were linked to higher numbers of fish, more species overall and, therefore, potentially more fishing opportunities for northerners.</p><p>Initially, we were surprised to learn that warming was increasing the distribution of cold-adapted fish. We reasoned that modest amounts of warming could lead to benefits such as increased food and winter habitat availability without reaching stressful levels for many species.</p>
Photo of Arctic grayling (left) and Dolly Varden trout (right). Alyssa Murdoch / Lilian Tran / Nunavik Research Centre and Tracey Loewen / Fisheries and Oceans Canada<p>Yet, not all fish species fared equally well. Ecologically unique northern species — those that have evolved in colder, more nutrient-poor environments, such as Arctic grayling and Dolly Varden trout — were showing declines with warming.</p>
Fish Strandings and Buried Eggs<p>Recent news headlines run the gamut for Pacific salmon — from their increased escapades <a href="https://nunatsiaq.com/stories/article/more-pacific-salmon-showing-up-in-western-arctic-waters/" target="_blank">into the Arctic</a> to <a href="https://www.juneauempire.com/news/warm-waters-across-alaska-cause-salmon-die-offs/" target="_blank">massive pre-spawning die-offs</a> in central Alaska. Similarly, results from our study revealed different outcomes for fish depending on local climatic conditions, including Pacific salmon.</p><p>We found that warmer spring and fall temperatures may be helping juvenile salmon by providing a longer and more plentiful growing season, and by supporting early egg development in northern regions that were previously too cold for survival.</p><p>In contrast, salmon declined in regions that were experiencing wetter fall conditions, pointing to an increased risk of flooding and sedimentation that could bury or dislodge incubating eggs.</p>
Headwaters of the Wind River within the largely intact Peel River watershed in northern Canada. Don Reid / Wildlife Conservation Society Canada / Author provided<p>Interestingly, we found that certain climatic combinations, such as warmer summer water temperatures with decreased summer rainfall, were important in determining where Pacific salmon could survive. Summer warming in drier watersheds led to declines, suggesting that lowered streamflows may have increased the risk of fish becoming stranded in subpar habitats that were too warm and crowded.</p>
The Fate of Northern Fisheries<p>The promise of a warmer and more accessible Arctic has attracted mounting interest in new economic opportunities, <a href="https://doi.org/10.1016/j.marpol.2019.103637" target="_blank">including fisheries</a>. As warming rates at higher latitudes are already <a href="https://www.ipcc.ch/sr15/" target="_blank">two to three times global levels</a>, it seems probable that northern biodiversity will experience dramatic shifts in the coming decades.</p><p>Despite the many unknowns surrounding the future of Pacific salmon, many fisheries are currently <a href="https://doi.org/10.1080/03632415.2017.1374251" target="_blank">thriving following warmer and more productive northern oceans</a>, and some <a href="https://doi.org/10.14430/arctic68876" target="_blank">Arctic Indigenous communities are developing new salmon fisheries</a>.</p><p>As warming continues, the commercial salmon fishing industry is poised to expand northwards, but its success will largely depend on extenuating factors such as <a href="https://www.eenews.net/stories/1060023067" target="_blank">changes to marine habitat and food sources</a> and <a href="https://www.yukon-news.com/news/promising-chinook-salmon-run-failed-to-materialize-in-the-yukon-river-panel-hears/" target="_blank">how many fish are caught during the freshwater stages of their journey</a>.</p><p>Even with the potential for increased northern biodiversity, it is important to recognize that some northern communities may be unable to adapt or may <a href="https://thenarwhal.ca/searching-for-the-yukon-rivers-missing-chinook/" target="_blank">lose individual species that are associated with important cultural values</a>.</p>
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By Joni Sweet
If you get a call from a number you don't recognize, don't hit decline — it might be a contact tracer calling to let you know that someone you've been near has tested positive for the coronavirus.
Interviews With Contact Tracers<p>Contact tracing is a public health strategy that involves identifying everyone who may have been in contact with a person who has the coronavirus. Contact tracers collect information and provide guidance to help contain the transmission of disease.</p><p>It's been used during outbreaks of sexually transmitted infections (STIs), Ebola, measles, and now the coronavirus that causes COVID-19.</p><p>It starts when the local department of health gets a report of a confirmed case of the coronavirus in its community and gives that person a call. The contact tracer usually provides information on how to isolate and when to get treatment, then tries to figure out who else the person may have exposed.</p><p>"We ask who they've been in contact with in the 48 hours prior to symptom onset, or 2 days before the date of their positive test if they don't have symptoms," said <a href="https://case.edu/medicine/healthintegration/people/heidi-gullett" target="_blank">Dr. Heidi Gullett</a>, associate director of the Center for Community Health Integration at the Case Western Reserve University School of Medicine and medical director of the Cuyahoga County Board of Health in Ohio.</p>
“You’ve Been Exposed”<p>After the case interview, contact tracers will get to work calling the folks who may have been exposed to the coronavirus by the person who tested positive.</p><p>"We give them recommendations about quarantining or isolating, getting tested, and what to do if they become sick. If they're not already sick, we still want them to self-quarantine so that they don't spread the disease to anyone else if they were to become sick," said Labus.</p><p>Generally, the contact tracer won't ask for additional contacts unless they happen to call someone who is sick or has a confirmed case of the virus. They will help ensure the contact has the resources they need to isolate themselves, if necessary. The contact tracer may continue to stay in touch with that person over the next 14 days.</p><p>"We follow the percentage of people that were contacts, then converted into being actual cases of the virus. It's an important marker to help us understand what kind of transmission happens in our community and how to control the virus," said Gullett.</p>
Why You Should Participate (and What Happens If You Don’t)<p>A <a href="https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30457-6/fulltext" target="_blank">Lancet study</a> from June 16, which looked at data from more than 40,000 people, found that COVID-19 transmission could be reduced by 64 percent through isolating those who have the coronavirus, quarantining their household, and contacting the people they may have exposed.</p><p>The combination strategy was significantly more effective than mass random testing or just isolating the sick person and members of their household.</p><p>However, contact tracing is only as effective as people's willingness to participate, and a small number of people who've contracted the coronavirus or were potentially exposed are reluctant to talk.</p><p>"Contact tracers have all been hung up on, cussed at, yelled at," said Gullet.</p><p>The hesitation to talk to contact tracers often stems from concerns over privacy — a serious issue in healthcare.</p>
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By Andrea Germanos
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