Category: Energy

Urban heat island
Urban heat island

What’s a urban heat island? To answer this question we need to start from explaining that air temperature and surface temperature are two different things. Have you ever walked on the beach bare foot? Of course, so you know the difference. The sand can get way hotter than the air. But why? What makes the difference here? The color and the chemical composition of the surface.

Streets and roofs are usually dark and, because of this, they absorb more heat than white objects. Asphalt and concrete is also water resistant. Didn’t you notice that after the rain there’re a lot of puddles here and there? This happens because water can’t pass through the concrete. In our cities, everywhere you look you can see concrete, asphalt, roofs and parking lots. All of this contributes to the urban heat island effect, which explains why cities are usually a few degrees hotter than the countryside surrounding them.

isola di calore

This affects also the night time. During the night buildings and streets release the heat absorbed during the day.
Does this happen even in winter? Yes. Maybe we don’t feel it, but the city is hotter that the surround areas even during the coldest months of the year. This is why, in some cities, snow it’s not that common.

How to produce energy
How to produce energy

You don’t always have to turn off lights if..

We have always been told and reminded repeatedly to turn off unneeded lights to save energy, but this is not always true. If you have special energy saving light bulbs called CFLs, turning them on and off too often may shorten their life spans. So if you’re going to be gone just a few minutes you can leave them on.

Burning coal generates electricity, but not everywhere.

In Europe coal accounts for 25% of all the fuels burnt to generate electricity, in the United States 39% and 75% in China. When it is burned in a power plant it provides the heat to make steam which moves a turbine that generates electricity. In some places however coal is used much  less, like in California where only 1% of electricity is generated from this fossil fuel.

Putting our clocks forward in Spring is good for the planet.

When Daylight Saving Time starts each spring, we move an hour of daylight toward the end of the day. In just four weeks of DST scientists calculated that we save 0.5% of electricity. This doesn’t sound like much but it is the same as 1.3 billion kilowatt-hours, the amount of electricity 100,000 houses use in an entire year.

The force in water makes electricity.

When you put your open hand in a stream or river you can feel how powerful the flow is. We can use this power to generate electricity. Thousands of years ago ancient populations built water wheels and mills to grind grain using the power of flowing water. Today many countries use hydropower, that is the electricity generated by water flow. Hydropower plants are usually inside dams. Sometimes dams are not built and part of a river is channeled to make electricity.

Wind can generate electricity too!

Even thousands of years ago people understood that wind is a strong force. They invented windmills to harness it. Like water, wind is a renewable energy source. Big wind turbines, sometimes over 100 meters tall, generate electricity today. They look simple but some have 8000 parts! Countries like the United States, Germany, Italy and Spain are making a lot of electricity using wind.

The sun’s power fuels a satellite for 50 years!

The sun is a great source of energy, its rays send Earth 10,000 times the energy we use all around the world every day! Space industry has used solar power for more than 50 years. In fact space craft use solar cells to capture this energy to this day. Vanguard1 was the first artificial satellite to use  solar cells, it is the oldest artificial satellite still orbiting the Earth.

Trash can also generate electricity.

Why “waste” all the waste products that we flush down the toilet or put in our trashcans? When organic waste breaks down it releases methane, a natural gas. Trapping that gas is useful because it can be burned as a fuel to produce electricity. This has another benefit: methane is a greenhouse gas, when we use it we are keeping it out of the atmosphere. This is good for the environment.

Are electric vehicles great everywhere?

Electric cars don’t  pollute the air when they go. They are powered by electricity in their batteries. But are they really non polluting? It depends on where you live. When you charge the car’s battery, you are getting electricity from a power plant. If this electricity comes from renewable sources, electric  cars are great for the environment. If your power comes from a coal burning power plant then it is not as good. The car itself does not pollute but the electricity that charges it does.

More efficient batteries are the way to go.

Batteries have improved a lot since they were invented in 1799 but they need to be improved even more before we can store enough energy for us to use solar and wind power without running out of electricity on cloudy or windless days. We need to be able to store more energy for longer. Researchers are working hard to solve this problem.

Energy is measured in BTUs or calories.

Just like temperatures are measured in degrees which could be Fahrenheit or Centigrade, there is a unit of measurement for energy as well. This way we can make comparisons with our figures. In UK and USA this unit is the BTU (British Thermal Unit) which is the energy needed to raise the temperature of one pound of water by one degree Fahrenheit. In Europe and most of the world the unit is the calorie, the energy needed to raise the temperature of 1gram of water by one degree Centigrade.

Coal and fossil fuels
Coal and fossil fuels

What are fossil fuels?

Since the chemical remains of prehistoric plants and animals are what make coal and oil, these are called fossil fuels and this is what you put in your gas tank when you fill up your car. Carbon is a great part of all living things on earth, even humans! There are 9 kilos of carbon in a 50 kg person. Plants are even more full of carbon, not quite 50% of a plant is carbon.

You are 18 percent carbon. Plants are 45 percent carbon.

If there is so much carbon everywhere why isn’t everything black and sooty? How can flowers be blue or tigers orange? This is because carbon is an element that combines easily with other elements to form different substances. These compounds of carbon are very different from pure carbon.

The smallest part of any element is called an atom. A carbon atom combines easily with two atoms of oxygen. The compound that is formed is carbon dioxide..

“C” is the symbol for carbon, “O” is the symbol for oxygen, so carbon dioxide is often called “C-O-2, and written “CO2” . CO2 is an invisible gas and it is really important for life.

Where do living things get carbon from?

During photosynthesis plants absorb CO2. They keep the carbon and give out the oxygen. People and animals breathe in the oxygen and breathe out carbon dioxide.

The fact that animals and plants depend on each other works out fine. Plants and animals have lived and died for a very, very long time. Their remains are buried deep beneath the earth’s surface. Heat and pressure have transformed these remains into oil and natural gas.

Plants and animals when they died were buried under water and dirt for hundreds of millions of years. Heat and pressure turned the dead plants and animals into oil, coal, and natural gas.

What happens to all the remains of ancient dead plants and animals?

It turns into what we call fossil fuels: oil, coal, and natural gas. This is what we now are using  to produce energy in our modern world. We burn these carbon-rich materials in cars, trucks, planes, trains, power plants, heaters, speed boats, barbecues, and many other things that require energy.

 

What happens to the carbon from fossil fuels?

Heat is the main product and the reason why we burn fossil fuels, other by-products are water and CO2 there are some solid products too, like soot, ashes and grease.

All the ancient carbon stored in those prehistoric plants and animals ends up here in our modern atmosphere. Since people have been burning fossil fuels for about 200 years all that carbon that took hundreds of millions of years to getting stored up is being released now. This creates an imbalance in the chemistry of our atmosphere.

Is carbon in the air good, bad, or just ugly??

CO2 is a greenhouse gas.  A greenhouse gas is a gas that helps keep the Earth warm because it traps heat and allows Earth to keep some of the sun’s energy on earth without letting it go back out into space.

If the greenhouse effect did not exist Earth would be completely frozen. We would not be able to live here.

Without the greenhouse effect, Earth would be a ball of ice.

A greenhouse keeps pants warm by trapping the sun’s energy inside.

So, CO2 and other greenhouse gases have a positive effect on Earth—up to a point.  CO2 is very efficient and more of it is not always a good thing, when CO2  increases so does the temperature on Earth.

In all the history of the Earth every time the percentage of CO2  in the atmosphere increased, there was also an increase in the global temperature. What is even more important is another fact, the more the temperature on Earth increases so does the percentage of CO2 .

Studies are being done to calculate how much carbon plants absorb from the atmosphere and how carbon is distributed around the world.