Blato ; Priscapac, 25.05. – 02.06. 2001

Eotvos Joseph Gymnasium – Budapest, Hungary

Gymnasium – Blato, Croatia

Learning about renewable energy

Can you imagine life without television, cars or computers? What if you had to cook your dinner over a fire or fetch water from the river? It might be fun for a camping trip, but you probably would not to do it every day. But, that`s how life was before scientists and inventors discovered ways to use energy to make our lives easier.

Today, most of the energy we use comes from fossil fuels. While fossil fuels are still being created today by underground heat and pressure, they are being consumed more rapidly than they are created. For that reason, fossil fuels are considered nonrenewable; that is, they are not replaced as soon as we use them.

Because our world depends so much on energy, we need to find sources of energy that will last a long time. What if there was a type of energy that never ran out? It is called renewable energy.

In addition, because there are so many people on Earth using fossil fuels, we create a lot of pollution. So, we should also use energy sources that produce as little pollution as possible. Generally, renewable energy systems are less polluting than fossil fuel systems.

Renewable energy systems use resources that are constantly replaced. Examples of renewable energy systems include solar, wind and geothermal energy. We also get renewable energy from trees, plants, rivers and even garbage.

Solar energy

We can use the energy in sunshine to warm and light our homes (solar heating), heat our water(solar water heating), and provide electricity to power our lights, stoves, refrigerators...(photovoltaic energy).

Solar water heating

Sun can heat water for bathing and laundry. Most solar water heating systems have two main parts: the solar collector and the storage tank. A common collector is called a flat-plate collector, and is usually mounted on the roof.Thic collector is a box with a transparent cover that faces the sun. Small tubes run trough the box, carrying the water. The tubes are mounted on a metal apsorber plate, which is painted black to absorb the sun`s heat. The storage tank can be just a mdified water heater, but ideally it should be larger, well-insulated tank.

Wind power

One of the alternative for solar energy is using wind power. Did you know that wind is considered an indirect form of solar energy? This is because wind is driven mainly by temperature differences on the surface of the earth that are caused by sunshine.

For centuries, the wind has been used to sail ships, grind grain and pump water. Now, people use wind to generate electricity. The windmills built long ago had many blades, but today`s wind turbines usually have just two or three blades, but they are much longer. The blades run a generator that produce electricity. The longer blades andthe faster the wind speed, the more electricity the turbine generates. Wind turbines are placed on towers because the wind blows harder and more steadily above the ground.

Monitoring the Sun`s radiation

The Sun`s energy that is available for collection depends on the intensity of the light, and on how long the Sun shines. To be able to compare the Sun`s energy in different parts of the world, the scientists measured how much energy falls on each square meter of land (kWh/m²).

Interpreting a map:

Q: Look at the map on the privious page and compare different parts of the world based on data shown on this map. What can you say about Adriatic Sea area?

A: We can see that the quantity of Sun`s energy is biggest around Equator and it`s getting lower as we go to the poles. Adriatic area, especially it`s southern parts, where Priscapac is settled, gets about 1600 kWh/m². But, as we are interested in summer time,when the are tourists in tourist village, that number is even bigger.

Our job was to made a plan about using solar energy for water heating in Priscapac, the tourist village where we were staying during this Eurocamp. We took some prospects about Solar water haeting systems from local suppliers. and we choose one of them for our project. It has solar panels and tanks that have to be mounted on the roof

A solar log sheet:

The amount of sunlight arriving varies during the day, and it varies from day to day. For monitoring the Sun`s radiation we made a simple sundial and record the position of the end of the shadow several times during the day. From the length of the shadow and length of the stick we can estimate the angle of the Sun. We need this so we can calculate the angle of the solar panels. The panels must be vertical to the Sun at highest point (at 12:00)

We also measured the air temperature, so we can see how temperature variing during the day, and how it depends on weather.

date: 26.05.2001.

time	length of the shadow (cm)	angle of the Sun, α	temperature (° C)	Weather
9:45	33	47°29´22˝	24	Sunny
10:15	27.5	52°37´27˝	23	sunny
10:45	22	58°34´13˝	23	half-cloudy
11:15	19	62°10´33˝	22	half-cloudy
11:30	18	30°	20	half-cloudy
11:45	17.5	29°05´07˝	20	half-cloudy
12:00	16.5	27°16´46˝	21	half-cloudy
16:00	39	43°04´40˝	26	sunny
16:30	50	35°45´14˝	28	sunny
17:00	61	30°32´51˝	28	sunny
17:30	74.5	25°47´27˝	26	sunny
18:00	94	20°57´21˝	26	sunny

table: A solar log sheet

notes:

1. weather: cloudy, half – cloudy, sunny,

2. length of the stick = 36 cm

3. estimate the angle of the Sun (α):

tg α = (length of the stick) / (length of the shadow)

This is the scheme of the tourist village.

reception

restaurant

market

A 1

A 2

B 1

B 3

C 1

C 2

B 2

C 3

C 4

It has 9 bungalows marked with a letters A, B and C.

- A bungalows have 12 apartments, each of them is for 5 persons

- B bungalows have 16 apartments, eight for 5 persons, and eight for 2 persons

- C bungalows have 21 apartments, 16 for 5 persons, and 5 for 2 persons

So, when all capacities are full, there are about two hundred people living there.

The diagram below shows average daily water quantity per person. We can see that the man spends daily about 140 l of water, of which 90 l of warm water.

PROSJECNA DNEVNA POTROSNJA VODE

If we divide this spending over bungalows, needed quantity of water is:

bungalow	needed quantity (l)
A 1	1800
A 2	3600
B 1	2520
B 2	1260
B 3	1260
C 1	1980
C 2	2260
C 3	1800
C 4	2260

Our system will consists of two solar water-heating models:

First one (LX 110) has 180 l tank, and panel area of 2m², and the second one (LX 305) has bigger, 300 l, tank with the panel area of 4m^2.

MODEL LX 305 MODEL LX 180

table: Distribution of solar water heating models over bungalows

bungalow	needed quantity of water (l)	model LX 110 (pieces)	model LX 305 (pieces)	total panel area (m²)
A 1	1800	0	6	24
A 2	3600	0	12	48
B 1	2520	1	8	34
B 2	1260	1	4	18
B 3	1260	1	4	18
C 1	1980	1	6	26
C 2	2260	1	7	30
C 3	1800	0	6	24
C 4	2260	1	7	30

On the roof of building where the restaurant is, there are a lot of chimneys and ventilation holes so it is impossible to put solar panels on it. Because of that, we suggest putting a roof construction above the parking place, and put solar panels, that will heat water for restaurant and market needs, on it. In this way, parking place will be in the shadow and it would get sufficient area for solar panels.

Using wind power

Wind is another source of renewable energy. A wind turbine collects energy from moving air. The wind spins the rotor blades round, and this turns the generator.

Because the wind speed isn’t so big here on Prišćapac, we can use wind only as an alternative source of energy, maybe for public light or something like that.

At first, we have to measure wind speed. For that purpose we use a simple method shown on diagram below.

We measured the distance from the foot of the rule to the point where the ball lands. To calculate the wind speed, we have to multiply this distance by 9.

table: measuring wind speed

rule – ball distance (m)	wind speed (m/s)
0.577	5.2
0.56	5.1
0.53	4.8
0.55	5.0
0.61	5.5

average wind speed: v= 5.1 m/s

This is an image of one wind turbine.

The amount of energy, which a turbine can collect from the wind, depends on the wind speed and on the length of the turbine blades.

Available power:

P= A×d×v³

(A-area swept out by blades, d-density of air, v-wind speed)

We will adjust the dužinu of the blades to our needs. For example, if the blades are 8.5 m long, the turbine can provide 36 kW of power when the wind speed is 5.1 m/s.

Making a poster: Solar power history

We found some notes about this issue on Internet. This is summary of one of them:

Ø Ancient Egyptians built places to live that allowed stored energy from the sun during the day, and heat release during the night.

Ø Egyptians also used sun as a part of their mummification process.

Ø Greek soldiers, with help of Archimedes, focused light on a Roman fleet by using mirrors. The mirrors were used to concentrate the energy of the sun, and cause the fleet’s sails to burn.

Ø Roman bathhouses had famous south facing windows that heated the rooms.

Ø 1767. the world’s first solar collector was built by Swiss scientist Horace the Saussare

Ø In 1891. the first commercial solar water heater was patented by Clarence Kemp.

Ø In 1958. a small satellite of US Vanguard was powered by a less than one watt power solar cell

This is the poster we made.

But, renewable energy is still a future for lots of people, including us. It’s still too expensive and many of us can’t afford it. So we have to be satisfied with this one – nonrenewable. It is much cheaper, but makes a lot of pollution. And, since it’s nonrenewable, we have to save it.

This is our suggestion how to do that.

It saves energy when you….	It wastes energy when you…
Turn off lights that you don’t need	Lights are on in a empty room
Wash and rinse dishes in two pans	Wash dishes under a running faucet
Keep oven door closed. Use a clock to tell you when food is ready	Peek in oven while food is cooking
Use a pan the size of the burner on the stove	Put a little pan on a big burner on the stove
Turn off TV or radio when nobody is watching or listening	The TV or radio plays to an empty room
Close the curtains in the room you’re cooling	The sun shines into the room you’re trying to cool
Take a shower, instead of bath	Fill bath tub to the top
When it’s cold, wear warm clothes in several layers	When it’s cold, wear thin clothes
When it’s cold, close outside door quickly	When it’s cold, leave outside doors open longer than needed
Fix the leaking faucet	Have a leaking faucet
Open and close the refrigerator door quickly	Keep the refrigerator door open longer than needed
Stuff rags, paper or rug in crack under outside door	Have a crack under the outside door
Toast bread in toaster, not in oven	Toast bred in oven, not in a toaster
Iron clothes all at the same time	Iron clothes one or two items at a time
Cook many items in oven at the same time	Cook only one item in a oven
Stop cooking when food is tender	Cook food longer than needed
Wash clothes in cold water when possible	Wash clothes with more hot water than it’s needed
Put a lid on pan when cooking. It keeps heat in	Leave lid off pan when cooking
Have good insulation in outside walls and roof	Have poor insulation in outside walls and roof
Run ht washing machine with a full load	Run the washing machine without many clothes in it

Conclusion

Trough this program we made on Eurocamp Priscapac we discussed about advantages and disadvantages of using solar energy, and we came to conclusion that although solar power is not used by many people, because it is expensive, it is the most accessible source of energy. Beside that, it’s ecologically acceptable because it doesn’t pollute the environment.

This was made by:

1. Kristina Baltić

2. Marija Cetinić

3. Regina Kiss

4. Orsolya Králik

5. Bojana Oreb

6. Zsófi Sugár

7. Margit Szellő

8. Juli Váli

With help of prof. Ivana Biško

Thank you!

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