What's the Water-Energy Nexus?

What's the Water-Energy Nexus?

Aug 17, 2021

Aug 17, 2021

In 2019, in honor of Human Rights Day, Amnesty International surveyed over 10,000 Zoomers (we're talking Gen Zs here, not people who use Zoom). The question that really stuck out was 'Which, if any, of the following do you see as the most important environmental issues facing the world or facing your country?' Twelve options were given, ranging from 'global warming', to 'water quality', to 'air pollution' to 'none of these'. (Wait... NONE? Who said NONE?!) Respondents chose global warming and air pollution as the two most important issues facing the planet and their country, respectively. Those of you who read my post on the 'Sustainability Paradox' are probably asking the same thing I am: Where is the option for 'All of the above'? Yes, we all dreaded the 'D: All of the above' choice on our 9th grade history tests, but in this case 'All of the above' is the best possible answer. That said, it does not mean we should be trying to solve every problem at once. In fact, blindly trying to solve each problem without thinking about how we might impact other parts of the environmental equation is kinda how we got into this mess in the first place. It's about time we change that.


Green Chemists use the term 'regrettable substitution' to describe the replacement of a hazardous or environmentally unfriendly chemical, material, or product with one that eliminates the original problem, but ends up causing new problems elsewhere. The Environmental Defense Fund gets straight to the point, calling it 'swapping the devil you know for the devil you don't'.

Unsurprisingly, 'regrettable substitutions' have happened a lot.

Example: cars and the fuel that powers them.

Have you ever bought 'Unleaded Gasoline' at the gas station and wondered why they need to say it is 'unleaded'? Well, way back in the day, when our great-grandparents and grandparents were trading in their dinosaurs for their own version of Greased Lightning, gasoline had tetraethyl lead injected into it to stop the engine from making funny knocking noises. Eventually, lead in gasoline was linked to health issues (and maybe even a multi-decade crime epidemic in American cities... yikes) and was eventually phased out by the U.S. Environmental Protection Agency (USEPA). No more lead poisoning (at least from the tailpipe). To prevent engine knocking and improve air quality from a car's tailpipe, the lead was substituted with a chemical called methy-tert butyl ether, or MTBE for short. MTBE did what it was supposed to do, limiting the aerial toxins from driving. Problem solved, right? Slow down, speed racer. While the air became cleaner, MTBE made water quality worse and was eventually banned by the USEPA to protect drinking water resources. MTBE was the ultimate 'regrettable substitute' here, solving one problem and creating another. Fortunately, the current use of ethanol (insert corny joke here) in our gasoline has reduced toxic air emissions and poses no threat to drinking water supplies.

As new products, including more 'sustainable' ones, are being developed and sold, it is becoming more and more important that we aren't trading something like a decrease in greenhouse gas emissions for an increase in air pollution, or less toxic materials in exchange for those that damage the ozone layer. To do this, scientists are developing a better understanding of how environmental problems are related to one another, sometimes in some not-so-obvious ways. And we think it's about time we learn about one of the most researched and complicated environmental tradeoffs out there, the 'water-energy-climate nexus'. Move over scientists, we're ready to save the planet, too!


Before we begin, let's start with a quick definition of the 'water-climate-energy nexus'. In short, the nexus refers to the water use needed to meet our energy needs, how energy use impacts climate change, and how climate change impacts water use and water resources, plus those exact same relationships in reverse. The term 'water-climate-energy nexus' is just a fancy way for scientists to say 'confusing environmental love triangle', yet it is among the most important relationships in the entire world, apart from Jay-Z and Beyonce (and us). Changing one impacts the other two, just like angering Beyonce is sure to anger Jay-Z and The BeyHive.

I could probably spend the next ten blog posts in this series going into the details of the 'water-climate-energy nexus'. There is just so much to talk about. Heck, a Google Scholar search for the topic came up with almost 150,000 peer-reviewed papers related to the topic.Instead, we will just do two lightning round lists of facts and tradeoffs, split into two pairings in the nexus: 'water-energy' and 'water-climate'. We will be covering 'water-climate' relationships in Part II of this blog post, so stay tuned on that one!

Also, heads up, this list will barely scratch the surface, so we will be back to cover more of these relationships in future posts. That being said, the clock... starts......... NOW!


Water Requires Energy. Part I

In 2017, the Congressional Research Service reported that roughly 4% of all energy use in the United States was related to the movement and treatment of water for industrial and residential use. So, your new product that needs more water to be made is also indirectly requiring more energy and the water you use throughout your house requires quite a bit of energy to get there. Yet another reason to get your dripping faucet fixed.

Water Requires Energy Part II: Electric Waterloo

It's no secret that the global population is increasing rapidly, while at the same time, water supplies are at record lows. Freshwater demand is expected to go up by 58% over levels from the year 2000 by 2030. To make sure everyone has enough water to drink and use in their products, some countries and states, like Israel and California, have invested in water desalination, or ‘desal' for short. Desal works by putting more pressure on seawater than Zac Efron's dad/basketball coach/theatre-hater put on him in High School Musical. The seawater is pressurized against a super thin membrane with holes so small that clean water can trickle through but salt can't. While this technology can help satisfy our thirst, it also currently requires8-25 times more energy than treating water from traditional sources, using traditional methods. Unfortunately, traditional methods can't treat seawater, so we will continue to need more energy to get more water as the freshwater well (aka rivers, streams, and groundwater) runs dry.

Guess what...Energy Also Requires Water

Water is one of the most important ingredients in producing energy. Nuclear power plants work by using the heat generated during nuclear fission to boil water that turns a turbine and creates energy, while gas power plants are cooled by water so they don't overheat. Good news, though! Slowly but surely, more of these sites are beginning to reuse water in cooling, rather than just using it once. Plus, over the last few years, a larger percentage of plants have actually been slated to use air-based cooling instead of water. Hopefully nothing 'regrettable' comes of it.

Energy Requires Water II: The Musical

When it comes to energy production, hydropower makes up about 17% of total energy production, according to the USGS. While this is great for reducing fossil fuel reliance, it should be noted that using natural water for energy comes at an environmental cost since it can impact fish migration and natural habitats, as well as change water temperatures, levels, and flow rates.

Energy Requires Water III: Revenge of the Shale

Natural gas, the single most controversial form of energy in America, is very water reliant. Millions of gallons of water (plus thousands of other gross chemicals, including, no joke, the chemical found in cinnamon scent) are pumped into the ground to break shale rock and release natural gas. As long as we rely on natural gas to power our lives, we also rely on using that limited freshwater supply.

Intermission: Time for Some Good News

Over the last few years, our ability to directly reuse wastewater has improved,supplementing our natural water needs...but it is coming at the cost of more energy. While water withdrawals for industrial energy have been going up, the amount of water needed per kWh of energy has been going down over the last 50 years, according to the Department of Energy, which is awesome news. Scientists have begun developing tools to measure the water-energy impacts of making and using products, including life cycle assessments (which are also used by Finch) and really cool looking geographical models to help them track water supplies used to manufacture products.

Finale: Water and Energy Tradeoffs Are Confusing

We've now learned that water and energy are intrinsically linked. Energy requires water and water requires energy. They are Yin and Yang, ebb and flow, tacos and Tuesdays...they complete each other. But this link is not a perfect 1-to-1 ratio, and this is clear when we think about products and the materials we use to make them. Companies can use materials that suck up water like a sponge, but use almost no energy, or the opposite can be true. To prove this, we decided to spend time thinking about fabrics. As you may know, we love a good time, so we partied hard in the Finch-iest way possible...by doing a thorough analysis of databases gathered by the British Department for Environment, Food, and Rural Affairs in 2009. Grab your favorite Kool-Aid and check out the results in the graph below.


Let's take a quick walk through what we are seeing in this graph. First, some quick definitions. There are three classes of fabric here:

'Natural' fabrics (in dark green), like cotton, are fabrics that come from plants or animals.

'Synthetic' fabrics (in coral), like polyester, are almost exclusively man-made through chemical reactions, and can be derived from fossil fuels.

'Regenerated' fabrics (in blue) kinda fill that middle spot in the Venn diagram between Natural and Synthetic because the material in Regenerated fabric and fiber comes from a natural source, the cellulose from plant fibrils and wood pulp, which is then dissolved in chemicals to make it fibrous.

Both natural and synthetic fabrics have their pros and cons, which you can read more about in our posts where we air the dirty laundry of the textile industry, spin a yarn about microplastics in synthetic fibers, or cuddle up into a bed of knowledge about sheets. Regenerated fibers are also really popular because their base component, cellulose, doesn't come from oil and it is super strong (it's the reason trees don't collapse under their own weight), and the chemical processing allows scientists to change the properties of the fabric depending on the product.


Back to the graph...the further right you go, the more energy was used to make the fabric, and the further up you go, the more water was used. There were quite a few fabrics with low energy and water footprints that ended up down in the bottom left, most of which were 'Natural'. All five fibers in the green area required less than half the energy of the most power hungry fabric, and less than 25% of the water that the thirstiest one required. You really can't go wrong (from a water and energy perspective) if you stick to items made from materials listed in the green area next time you go shopping.

On the other hand, fabrics shown in the red area (in the top right part of the graph) are those that require a lot of energy and a lot of water to produce. It's not too shocking to see that synthetic fibers, like nylon and acrylic, require more energy since some of those chemical processes require a bit of heat. What really rained on our parade was seeing the amount of water required for some regenerated and natural fibers, like viscose and cotton. It just goes to show that 'Natural' doesn't always mean better for the planet. Instead, it is more important to pay attention to the specific Natural materials you're choosing. For example, getting that cotton shirt instead of the polyester one could cut your energy footprint by about 25%, but it will come at the cost of using about 9x more water.

All those materials in the middle of the graph come with tradeoffs. Some, like polyester, don't need a lot of water, but use a ton of energy, while modal requires 20% less energy than polyester, but at the cost of almost 5x the amount of water. Meanwhile, lyocell and PLA (which is short for Polylactic acid, is one of the most used bioplastics in the world, and is a common material for 3D printing) sit right in the middle, earning a solid C+ in ‘Being a 'Sustainable' Fabric 101'. However, the tradeoffs are everywhere, not just in the middle! There is a lot to think about here, so you may need to make the choice that is best for you and your life. More on that below!


Knowledge is only good for knowledge's sake, right? Wrong! You have this information, now go use it!

I'm sure a parent has told you the same thing a million times, but turn off the faucet when you are brushing your teeth or are otherwise not using it. Wasting water also wastes energy and directly contributes to climate change, so turning off the faucet can get us all out of some hot water!

Guess what... a parent also probably told you to turn off the lights when you leave the room. Save energy, save water, save Earth!

You now have this handy dandy chart to help you make better decisions when you are shopping for a new shirt. Use that knowledge and share it with your family and friends! Try to buy fabrics in the bottom left of the chart and avoid those in the top right if you can. When that's not possible, and you have to weigh tradeoffs between water and energy use, let us offer some advice: Do what is the most beneficial for your life and the lives in your local community. For example, if you live in the southwestern United States or want to purchase clothing from that area, you may want to shy away from water-intensive fabrics like cotton and nylon, since places like California are currently in their 8th most significant drought period since 2007.On the other hand, if you buy clothes made in a state where more than 20% of the energy comes from the worst energy source we have, coal (looking at you: AR, CO, IA, IN, KS, KY, MI, MO, MN, MT, NE, NN, ND, OH, UT, WV, WI, or WY), you may want to lean toward something with a higher water use to save on energy and the related emissions.

Find clothing and shoes made of recycled materials! While recycling polymers, synthetic materials, and natural materials, like cotton, still requires energy, recycling still uses significantly less energy than making or harvesting those materials from scratch. For example, according to the Textile Exchange's 2020 Report, recycled polyester is on the rise, making up 21% of all polyester clothing by diverting more than 26 billion plastic bottles from waste, which is good news on its own. In terms of energy and water, a very recent study in the Textile Research Journal found that using recycled polyester cut water requirements in production by two-thirds, while a 2017 study by the Swiss Federal Office for the Environment found that using recycled polyester could lead to a 59% reduction in energy use. Based on our calculations, if you bought just one t-shirt made of recycled polyester instead of virgin polyester, you would be indirectly saving 3.5-4.5 kWh of energy, which is roughly the same amount of energy needed to charge your iPhone for 2 years!

As awesome as buying clothes made of recycled materials can be, studies have proven time and time again that reuse is still the undisputed heavyweight champ. Buying a shirt second-hand or extending its lifetime by learning how to sew or bringing it to your local tailor saves way more water and energy than buying a recycled material shirt ever will.

Feel guilty about your fabric choices after seeing our analysis above? Don't! Instead, aim to try something new in the future. A recent study from the journal, Sustainable Production and Consumption, found that in America, about half of the global warming and energy impacts for a pair of jeans or a t-shirt come from washing and drying. So, instead of tossing that guilt-ridden cotton tee, make sure to wash your clothes with cold water, tumble dry or air dry when possible, and make sure your washing machine load is very full before you press 'start'. That will help you save water and energy that can offset the impacts of the shirt in the long run.