Smart Cities - How can we use Environmental Sensors?
Environmental sensors are able to measure trends and the health of the environment. Often if we aren't measuring things we can't be sure if they are working correctly or not. When you were a baby your parents probably has a temperature monitor in your room to make sure you weren't too hot or too cold. They may have had an audio monitor to see if you were awake.
You probably wear watches that can measure how active you are each day, if you've had a good night's sleep and your heart rate. The individual data sets are important and when we put them all together they give us a picture of our overall health. If we have targets or goals they may show us how close we are to achieving our goals.
Measuring the components that make up a Smart City can tell us if the city is in good health or not. This lesson will explore the types of sensors that are typically used in Smart Cities, how the information they collect is used, and how the knowledge gain from data can inspire new improvements, especially in the area of sustainability
Learning Objectives:
- Learn about different types of Environmental sensors and their uses (Water quality, air quality, weather sensors, beehive activity sensor, people counters, GPS trackers, bird/pollinator counter, sensors using Artificial Intelligence and Machine Learning to identify inconsistent data)
- What information do environmental sensors collect and how is that data used to innovate?
- How environmental sensors link with Smart City solutions?
2040 Movie - Environmental Dashboards
The 2040 movie looks at the use of Environmental Dashboards to display energy and water use in the town of Oberlin in Ohio, USA. The dashboards can be used for the whole town and also for specific buildings within the town.
Electricity
This Dashboard shows the amount of electricity the town uses. Probably the most important figure is the amount of CO2 emissions from electricity generation. The town imports electricity from a number of sources including coal, wind, solar, nuclear, landfill gas and hydroelectric. The CO2 emissions from electricity are 0.1 kg per person per hour (shown as 0.22 pounds per person per hour). In one year this would be 876 kg per person. To reduce global CO2 emissions many scientists are asking us to reduce GHG emissions by 7% every year. A Dashboard displayed on roads, in school and shopping centres would help us achieve this goal if yearly goals were clearly set.
Notice that the beaver mascot in the top left of the screen is happy. Studies have shown that the animated Dashboards show that people experience more emotions in relation to resource use. Because they have a connection with the data people are then more likely to change their behaviour. During the Millennium Drought Victorians were given the challenge of reducing our daily water consumption. Water consumption reduced from 220 to 155 litres per person per day because news agencies and the government were always reporting these figures. The same was demonstrated more recently with COVID infection numbers and even vaccination rates. Daily updates can help drive behaviour change.
Water consumption
This next Dashboard shows water consumption for the town. Unfortunately the cartoon fish is showing a sad face. This is probably because the town is using too much water. The town gets their water from Black river which is used to fill a reservoir. The stored river water is then purified and pumped to towers within the city to provide the necessary water pressure to homes (20m head of water). In Australia we call tap water - potable water.
The towns people are currently using 8.9 litres of water per hour (1.95 gallons per hour) or 214 litres per person per day. In Melbourne the daily consumption is 155 litres/day. To make the fish happy the towns people would need to use less water.
The town has a population of 8,300. The amount of wastewater produced is 11.47 litres per person per hour or 275 litres per person per day. The wastewater figure is higher than the tap water consumption because some roof water and stormwater must enter the wastewater system. This is a lot of wastewater to treat. The treated wastewater is discharge to Plumb creek.
Stream Health
The third screen on the Dashboard is for Stream health. Again the cartoon fish is sad. One reason is that the water level in Plum Creek is very high. The town has experienced a lot of rain and stormwater and farms probably direct excess water to this creek. When water levels are high the river waters are raging. These conditions are not good for aquatic animals living in the river.
The second reason is that Turbidity is very high. Turbidity is a measure of water clarity. A high Turbidity value means that the water is very cloudy. Any erosion of soil from new housing developments or agriculture that ends up in a river water will increase turbidity. This is very unhealthy for stream life.
Stream Health explained
Each Dashboard also has an accompanying page to explain what all the gauges mean and if the numbers are good or bad. The example below relates to the stream health of Plum creek. It is important to measure this waterway in particular because this is where the treated waste water from the town is being discharged.
Water level
Plumb Creek water level is very high. This because rainwater landing on streets, car parks, roofs and other hard surfaces finds its way rapidly into the creek. Land area that collects rainwater and then sends it to a local waterway is called a Catchment (in the US its called a Watershed). The rapid influx of water causes the creek level to rise. They also note that climate change will increase the frequency of extreme rain events, making flooding more frequent.
Dissolved oxygen
Dissolved oxygen is pessary for many fish, invertebrates, bacteria in plants that breath or respire oxygen in water. Fish use this gills to extract oxygen from the water. Bottom feeding organisms need less dissolved oxygen (1 to 6 mg/L), whereas animals that live in mid to upper waters require high levels of dissolved oxygen levels (6 and 15 mg/L). The dissolved oxygen gauge is showing 11 mg/L indicating that the Plum creek is well oxygenated.
Dissolved oxygen levels can go down for a number of reasons. If the water temperature is too high less dissolved oxygen can be carried by water. Based on the current water temperature of 15 degC (59 degF) the dissolved oxygen level of 11 mg/L is high. This is probably because of the recent rains and the high flow of the waterway. Also if there is too much organic material in water (e.g. leaf litter, dying algae, untreated wastewater) then bacteria and fungi will consume the oxygen dissolved in the water more quickly. Photosynthesis from plants, the movement of water over waterfalls, rocks and riffles, and the action of the wind all act to increase dissolved oxygen levels in water.
Turbidity
Turbidity measures the clarity of water. The current figure of 68 NTU shows that the water is more turbid. Clean river water should have a turbidity less than 35 NTU. High turbidity levels are not good for aquatic animals because they can damage fish gills, reduce photosynthesis and deposit large amounts of sediment in waterways. Poor land management practises during house construction and on agricultural fields leads to high turbidity in waterways.
Environmental Sensors at Peter Hopper lake Mill Park
Peter Hopper lake is a beautiful waterbody that is home to many birds, fish and other aquatic animals. The lake fills up with stormwater that is collected from house roofs and roads within the local area (water catchment). Unfortunately, the stormwater has high levels of nutrients, litter and is turbid (50 NTU). The lake is not able to remove these contaminants. As a consequence Peter Hopper lake has had many years of algal blooms. There are many different types of microorganisms that will feed on nutrients in water and produce blooms.
To reduce the occurrence of blooms it is necessary to treat the water using special mechanical filters (Gross Pollutant traps) to remove litter and leaves and also use plants in wetlands and raingardens to remove dissolved nutrients in the water. Plants and sedimentation ponds also reduce turbidity. Peter Hopper lake will be upgraded in the next few years so that water quality can be improved.
To help monitor the lake (like a patient in hospital) a water quality sensor has been installed close to where stormwater enters the lake. The sensor measures dissolved oxygen, pH (A measure of how alkaline or acidic the water is. A pH of 7.0 is neutral) and water temperature. The dissolved oxygen is one of the most important measures of lake health.
Peter Hopper lake Water Quality Dashboard
Measuring Turbidity in the Merri Creek at Galada Tamboore
A turbidity sensor has been placed in the Merri Creek to monitor the cleanliness of the water. Upstream urban development will likely result in an increase in turbidity due to an influx of silt into the waterway when roads and houses are constructed. The water from the Merri Creek is also used to fill up quarries in Epping that are home to Growling Grass frogs.
An online sensor is measuring turbidity, water temperature and pH. The turbidity sensor equipped on this sensor is very accurate and is equipped with a mechanical wiper so that it doesn't foul.
Smart Tank Mill Park Library
One day every house will be equipped with a Smart Tank. Smart tanks will help us to reduce stormwater flows and pollution to our waterways and also green our cities. The transformation will take place over the next 20 years and perhaps go into hyper drive when we try to reduce GHG emissions or when we experience our next big drought.
So what is a Smart Tank?
A smart tank measures the high of the water level in the tank. If the dimensions of the tank are knows, specially the area of the tank and height, then the volume of the tank can be calculated. Therefore, if the smart tank knows the fill height of the tank it can calculate the volume of water in the tank.
The smart tank can communicate with other computers (servers) on the internet. The smart tank is programmed to get rain forecast data and actual rain data from the Bureau of Meteorology.
The smart tank also needs to know how much roof space is connected to the tank so that it can calculate how much roof water will enter the tank with every mm of rain that falls. One mm of rain falling on a roof area of 1m x 1m produces 1 litre of water. So if a roof area is 200m2 and 50mm of rain falls this will add (200 x 50) = 10,000 litres of tank water.
The smart tank is truely smart. If it knows that a large rain event is coming and it doesn't have enough spare room then it will release some water from the tank. The smart tank can also let people know that more water should be used before the rain event. Excess rain tank water could be used for watering the garden or topping up a frog pond. Even releasing the excess tank water slowly to waterway is better than leaving it in the tank.
In the future every house and building will be equipped with large smart tanks.
Practical things you can do at home
Sensors are useful because they make data more readily available and easy to interpret. But you don't always need sensors and data. For example, it's clear that if you ride you bike to school or work it will be more sustainable that taking driving a conventional or electric car. The same applies to other items we consume or use.
Here are some simple examples about how you can make your home life more sustainable by using some utility bills for electrify and water.
Electricity - the average Victorian household uses between 10-14kWh of electricity per day. You can find out how much electricity your house uses from your quarterly electricity bill. The statement should give an indication of your average daily electricity consumption. Try to use less each quarter. This will save you both electricity and money. It will also give you a clue about that appliances in your household use the most electricity.
- Energy hungry appliances include: fridges, air conditioners or heaters, large televisions, entertainment systems, desktop computers, washing machines and dryers, inefficient lighting.
- Photo voltaic (PV) panels help reduce the amount of electricity used from the power grid. However PV solar panels are made from the burning of coal and take about 6 years of electricity production to pay back this debt.
- Solar panels may last for 30 years.
- A low electricity consuming household, with small PV panels is still better for the environment than a house that consumes more electricity. This is also a more equitable arrangement when we consider all people on the planet.
Water - the average Victorian uses 155 litres of water per day at home delivered as potable water. Each person uses an additional 475 litres of water per day used in the production of the food we eat. Water to produce food is invisible, but it is very real.
- You can monitor the amount of water you use at home using your quarterly water bill. If you want to see how much water you use daily you can also read the water meter at the front of your house.
- It is easy to consume less water simply by showering for 2 minutes, wearing clothes more than once before washing, and even washing some items of clothing by hand.
- You can collect water for your household by installing a rainwater tank. Tank water can be used to water the garden, grow food and wash clothes.
- The Permaculture Designer's Manual (Bill Mollison) recommends you install a 22,000 litre rain tank.
- The Very Edible Garden web site (https://www.veryediblegardens.com.au/iveg/rain-tanks/) also recommends that you install a 20,000 rain tank.
- The Tank Shop (https://www.tankshop.com.au/articles/what-water-tank-size-should-you-buy/) recommends the following:
- If you are looking to be largely self-sufficient, then the Australian Government (YourHome - https://www.yourhome.gov.au/water/rainwater) recommends up to 20,000 litres for a household with 2 adults and 2 children.
- Based upon this Tank Shop recommend a 22,700 litre water tank for a family, and this tank size generally provides the best dollar value per litre.
- If you live alone or with one other person, then about half that amount (10,000 litres to 15,000 litres) would be a good size to have your water supply needs met.
- Most homes have a 3,000 to 5,000 litre rain tank, so we've got a long way to go.