Lecture 5: Nexus water & energy Flashcards
Explain the concept of virtual water, why was this term conceived and how is it used.
Virtual water is the water hidden in the products, services, and processes people use & buy every day. The water used through the value chain to produce a good becomes “virtual” as it is no longer physically present there anymore.
The term was coined by Allan and it was originally developed to solve “water stress”. In theory, countries could spare national resources by trading water-intensive goods. Thus countries facing water stress could avoid conflicts over the distribution of water by importing water-intensive goods and reducing the demand for the resource.
More recently the term virtual water is used to quantify the water that goes into producing certain goods as well as tracking where water goes and which countries are importers or exporters of virtual water. It can be linked to the concept of water footprint, which is the analytical measurement used to count all types of water embedded in goods.
The concepts of virtual water and water footprint can be used to link consumption in one place and impacts on a water system somewhere else.
How many liters of water are needed to produce 1kg of beef? and how many for a cup of black coffee?
16000 l for 1 kg of beef
140 l for coffee
How are water and energy connected?
to move (extract, distribute, and treat) water electricity is required for the functioning of the pumps as well as for the production of pipes and other items used to transport water. Moreover, electricity is needed to warm up water for domestic use. On the other hand, to produce electricity water is essential. 90% of power generation is water-intensive. Not only for hydropower production which requires heavy flows of water, but also for power plant cooling. in the EU 43% of water withdrawal is for powerplant cooling purposes, and 50% in the USA.
What does the water-energy nexus refers to?
It refers to the interdependence between energy and water resources. The two resources have in common their essential role in development, both are required in good quantity to allow for a good standard of living. However, they remain quite different resources regarding their availability and physical form. The water-energy nexus also raises questions on the conflict of uses of the two resources. How much water should go toward domestic and direct needs and how much should go into power production? How can we balance tradeoffs? The UN world water development report of 2014 on water and energy thus suggest the joint development of the two sectors to minimize conflict and maximize efficiency.
what is green water
refers to the water in soil that is absorbed by plants and evaporated. It’s part of the natural water cycle, crucial for agriculture but not easily accessible for human use.
What is blue water?
This is the water in rivers, lakes, and aquifers that is visible and can be stored, treated, and transported for use in households, industry, and agriculture.
What is grey water?
Grey water is relatively clean wastewater from baths, sinks, washing machines, and other kitchen appliances. It’s not potable but can be recycled for uses like irrigation and industrial processes.
