Survey
Site survey
Firstly a little on location.. Below to the left is a map showing where our home is, in the province of Tarragonna, Catalonia, North East Spain.
You can see on the map to the right, the numbers correspond to the land use, 20 being terraced agricultural land, and 21 being forest. The majority of our land is listed for agricultural use, but as it has been left abandoned for so many years, succession has taken over and the forest has spread to cover a larger area than listed on this map.
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Sector analysis
I thought it could be useful here to look at the sectors interacting on the land to see if the wind and sunlight could potentially be harvested for energy use.
The main slope of the forested land is facing South-west, leading down to flat terraces. On the picture above to the left you can see the areas closest to the house. Any form of energy we create will lose power through transporting it long distances, so I will be focusing on this area around the home where it will be used.
My partner Oriol has created this map above to the right showing the sectors in force on the site. The house is shown in red, the green areas around the house are the places with more shade, and the yellow areas are the sunny spots. The dark blue arrows indicate the direction of the strong cold winds coming from the North, and the light blue arrows show the moderate and warm winds from the South. You can see the orientation of the house from the top right circle which indicates the North, and the sun represents the direction of light for the majority of the day.
My partner Oriol has created this map above to the right showing the sectors in force on the site. The house is shown in red, the green areas around the house are the places with more shade, and the yellow areas are the sunny spots. The dark blue arrows indicate the direction of the strong cold winds coming from the North, and the light blue arrows show the moderate and warm winds from the South. You can see the orientation of the house from the top right circle which indicates the North, and the sun represents the direction of light for the majority of the day.
Sunlight As you can see from the solar energy map to the right, this area has an average annual amount of 2,000 kWh/m, twice as much as our home in the UK. If you divide this by 365, you get 5.5 kWh/m2 per day. And the chart below shows the average hours of sunlight per day in our area. This ranges from a minimum of 4.45 hours in December to a maximum of 10 hours in July. The average daily sunlight over the year is 6.9 hours. |
Climate data for Barcelona
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean Year
Mean daily sunshine hours 4.80 5.71 6.45 7.33 7.87 8.73 10.0 9.09 7.30 5.80 4.86 4.45 6.9
Source: Agencia Estatal de Meteorología[6]
Mean daily sunshine hours 4.80 5.71 6.45 7.33 7.87 8.73 10.0 9.09 7.30 5.80 4.86 4.45 6.9
Source: Agencia Estatal de Meteorología[6]
The house
Below you can see some images of our house. The main part of the house has one room downstairs and one upstairs. There are two rooms attached onto the side of the main house, but these aren't used for living in yet as they have mud floors and a broken roof, previously only used for sheltering animals. So the main living areas we would want to provide light and power for are the downstairs and upstairs rooms in the main building. For a short time last year we were using a petrol powered generator to provide occasional electricity. This somehow broke very quickly, so the images with the light below are from very rare and special times..
You can see more of the house from the house plans below. The room map (below right) shows the downstairs rooms, with the two animal sheds on the left. You can see that the downstairs living room has only one window and this is very small, so the amount of natural light is very low.
Our resources
- A small house and low energy use - this is a very big advantage, after one and a half years with no power, our ability to live very simply has flourished, so our needs are quite small.
- Lots of sunlight in the local area.. South-west facing slopes, short winters, long summers..
- Been in touch with a charity in Bristol called Demand Energy Equality. They provide very low cost solar cells to projects so you can build your own panels at a fraction of the cost of buying them new
- As we're in a valley, large parts of the land get strong winds that pass reliably from the North. This wind could potentially be harvested
- My dad, Mike - financial adviser, race car driver and musician - is also a genius with electrical things, and has offered us help and advice, though from afar as he's in the UK. He seems excited by our off grid home, so I'm sure he will help with the calculations. I think with the electricity stuff, delegating tasks and asking for help from those who understand it will be a good, healthy, and less potentially electrocuting thing to do.
- For research I'm using many different websites, which I've listed in the appendix at the end of this project, but the resource that I'm finding the most useful and easy to understand is Do it Yourself 12v Solar Power, by Michel Daniek. This book was recommended to me by an off grid friend, and is really easy to follow, explaining all the elements of the system in very simple language, with some great ideas on how to make your own appliances.
Our boundaries
- Small budget, as always
- We're not sure how long we will be on this piece of land, as we rent and don't own it. Ideally we would like a system that we can take with us to a new home if and when we move on
- We're surrounded by pine forest on the north side, flat terrace land to the South, and in a low valley.
- We don't have any power to build the components, should we need it. So we'll need to do the constructing either off site at a friends, or hire a generator for power needs
- There is the option of supplying our emergency back up power and energy for high demand objects (such as power tools) with a petrol generator. But then comes the question of where we place our own personal boundaries of how rigid we want to be with our off grid home, if this fits with the ethics of our permaculture home, and if the use of this could be justified if we are trying to live sustainably.
Our energy needs
I've made a brainstorm of the things that we need power for. You can see this below.
The main things that we need power for:
Priority:
Priority:
- Charging laptops - 2 laptops, approx...
- Charging phones and cameras - We have two phones and cameras, but will have more with guests staying.
- Light - The lack of natural light in the house means that it is always very dark, but in the winter especially so. We are using candles and small solar lamps but we'd like to design a simple system of lighting that could illuminate the whole house.
- Stereo/music - At the moment we use our phones or laptops to play music until their batteries run out, after which we have to wait until the next charging opportunity, be it at a friends or a cafe. A proper stereo would be amazing, it is quite isolated and quiet where we are and we both really miss music.
Non priority but would-be-nice's:
- Fridge - We made a natural fridge, using two terracotta plant pots one inside the other, with sand in between. Topping up the sand with water means that as this water evaporates through the pores in the terracotta, heat is drawn out from the centre pot where you store your food. This keeps things cool, especially when it's really hot outside. But things don't ever become cold, and food often goes bad. There's also a limited space for food inside a plant pot. I would love a fridge, and so would like to look into the different options.
- Blender - Up until now I am using a giant pestle and mortar, but I love making smoothies and Oriol loves making soups. A blender would improve our diet for sure and make us both happy.
- Occasional power tool use - Electric sanders to restore the reclaimed scrap wood that we use to build everything. Also this doubles as an electric grinder for metal work. Power drills would change our lives.
- Power for a projector - when we are running courses here it would be really nice to run a projector to show photos, power points and movies if we can.
For now that's all that we need. In the future we may discover that we need other things, or perhaps as we continue to rebuild the house we will need more lighting, power sockets etc. It would be good to build a system that can be easily added onto if we choose to at a later date.
Power demands
I've done some calculations to see what our power needs will be from installing the list above. I've worked this out by looking at the wattage of the item, then multiplying this by the time used each day in hours, then dividing this by 1000. This gives the Kilowatt hours (Kwh) needed for the item per day.
So, Watts x time (hours) '/. 1000 = Kwh
Laptop: 0.2 Kwh per day.. x2 laptops = 0.4Kwh
Smartphone: 1 Kwh (per year!!) .. x2 phones = 0.006Kwh per day
6 L.E.D lights (10 watt bulbs) for 5 hours per day; 0.3 Kwh per day
Standard fridge freezer (less than 10yrs old); 1.35 Kwh per day
Blender, for 20 mins per day: Hand blender: 0.036 Kwh, High speed blender: 0.09 Kwh per day
Projector (low power version, 60 watts) : For 4 hours: 0.24 Kwh
Power tools (Important thing to remember: items with a motor need much more power (x2 of their normal needs) to start up..)
For example belt sander: 7.2Kwh needed to start up, 3.6kwh for 3 hours use
Stereo (av. 50 watt) for 6 hours per day: 0.3Kwh
Of course some of these things wouldn't be used every day. The power tools seem a completely unrealistic addition, taking our needs way high, so this I am going to leave out from now on, as there's no point in designing a huge expensive system for something that will be used only occasionally, I think these needs may tie into visits to friends or hiring a generator for the day, for now at least.
This leaves the total energy needs after leaving out the power tools: 2.68Kwh per day
But of course the projector wouldn't be used very often, so I could take that off the total too, as if we were running the projector one day we could hold off on the stereo, for example.. So that brings it down to 2.44Kwh normal daily needs.
I would like to look at how I can bring this need down as low as possible, so that the system I design can be as cheap as possible to install, a big priority for us! Higher energy needs means more batteries and whichever other elements we choose, which each can be pretty expensive.
So, Watts x time (hours) '/. 1000 = Kwh
Laptop: 0.2 Kwh per day.. x2 laptops = 0.4Kwh
Smartphone: 1 Kwh (per year!!) .. x2 phones = 0.006Kwh per day
6 L.E.D lights (10 watt bulbs) for 5 hours per day; 0.3 Kwh per day
Standard fridge freezer (less than 10yrs old); 1.35 Kwh per day
Blender, for 20 mins per day: Hand blender: 0.036 Kwh, High speed blender: 0.09 Kwh per day
Projector (low power version, 60 watts) : For 4 hours: 0.24 Kwh
Power tools (Important thing to remember: items with a motor need much more power (x2 of their normal needs) to start up..)
For example belt sander: 7.2Kwh needed to start up, 3.6kwh for 3 hours use
Stereo (av. 50 watt) for 6 hours per day: 0.3Kwh
Of course some of these things wouldn't be used every day. The power tools seem a completely unrealistic addition, taking our needs way high, so this I am going to leave out from now on, as there's no point in designing a huge expensive system for something that will be used only occasionally, I think these needs may tie into visits to friends or hiring a generator for the day, for now at least.
This leaves the total energy needs after leaving out the power tools: 2.68Kwh per day
But of course the projector wouldn't be used very often, so I could take that off the total too, as if we were running the projector one day we could hold off on the stereo, for example.. So that brings it down to 2.44Kwh normal daily needs.
I would like to look at how I can bring this need down as low as possible, so that the system I design can be as cheap as possible to install, a big priority for us! Higher energy needs means more batteries and whichever other elements we choose, which each can be pretty expensive.
Understanding electricity
I thought that it's probably pretty crucial that I try to expand my understanding of electricity and how it works. So here's some research I've been doing from some different sources.
Voltage
The voltage is a kind of electrical force that makes electricity move through a wire and we measure it in volts. The bigger the voltage, the more current will tend to flow. So a 12-volt car battery will generally produce more current than a 1.5-volt flashlight battery.
Current
Voltage does not, itself, go anywhere: it's quite wrong to talk about voltage "flowing through" things. What moves through the wire in a circuit is electrical current: a steady flow of electrons, measured in amperes (or amps).
Power
Together, voltage and current give you electrical power. The bigger the voltage and the bigger the current, the more electrical power you have. We measure electric power in units called watts. Something that uses 1 watt uses 1 joule of energy each second.
The electric power in a circuit is equal to the voltage × the current (in other words: watts = volts × amps). So if you have a 100-watt (100 W) light and you know your electricity supply is rated as 120 volts (typical household voltage in the United States), the current flowing must be 100/120 = 0.8 amps. If you're in Europe, your household voltage is more likely 230 volts. So if you use the same 100-watt light, the current flowing is 100/230 = 0.4 amps. The light burns just as brightly in both countries and uses the same amount of power in each case; in Europe it uses a higher voltage and lower current; in the States, there's a lower voltage and higher current. (One quick note: 120 volts and 230 volts are the "nominal" or standard household voltages—the voltages you're supposed to have, in theory. In practice, your home might have more or less voltage than this, for all sorts of reasons, but mainly because of how far you are from your local power plant or power supply.)
EnergyPower is a measurement of how much energy you're using each second. To find out the total amount of energy an electric appliance uses, you have to multiply the power it uses per second by the total number of seconds you use it for. The result you get is measured in units of power × time, often converted into a standard unit called the kilowatt hour (kWh). If you used an electric toaster rated at 1000 watts (1 kilowatt) for a whole hour, you'd use 1 kilowatt hour of energy; you'd use the same amount of energy burning a 2000 watt toaster for 0.5 hours or a 100-watt lamp for 10 hours. See how it works?
From http://www.explainthatstuff.com/electricity.html
The voltage is a kind of electrical force that makes electricity move through a wire and we measure it in volts. The bigger the voltage, the more current will tend to flow. So a 12-volt car battery will generally produce more current than a 1.5-volt flashlight battery.
Current
Voltage does not, itself, go anywhere: it's quite wrong to talk about voltage "flowing through" things. What moves through the wire in a circuit is electrical current: a steady flow of electrons, measured in amperes (or amps).
Power
Together, voltage and current give you electrical power. The bigger the voltage and the bigger the current, the more electrical power you have. We measure electric power in units called watts. Something that uses 1 watt uses 1 joule of energy each second.
The electric power in a circuit is equal to the voltage × the current (in other words: watts = volts × amps). So if you have a 100-watt (100 W) light and you know your electricity supply is rated as 120 volts (typical household voltage in the United States), the current flowing must be 100/120 = 0.8 amps. If you're in Europe, your household voltage is more likely 230 volts. So if you use the same 100-watt light, the current flowing is 100/230 = 0.4 amps. The light burns just as brightly in both countries and uses the same amount of power in each case; in Europe it uses a higher voltage and lower current; in the States, there's a lower voltage and higher current. (One quick note: 120 volts and 230 volts are the "nominal" or standard household voltages—the voltages you're supposed to have, in theory. In practice, your home might have more or less voltage than this, for all sorts of reasons, but mainly because of how far you are from your local power plant or power supply.)
EnergyPower is a measurement of how much energy you're using each second. To find out the total amount of energy an electric appliance uses, you have to multiply the power it uses per second by the total number of seconds you use it for. The result you get is measured in units of power × time, often converted into a standard unit called the kilowatt hour (kWh). If you used an electric toaster rated at 1000 watts (1 kilowatt) for a whole hour, you'd use 1 kilowatt hour of energy; you'd use the same amount of energy burning a 2000 watt toaster for 0.5 hours or a 100-watt lamp for 10 hours. See how it works?
From http://www.explainthatstuff.com/electricity.html
Item: HP Laptop running Vista: 47 Watts
Description:A laptop is a small-sized computer that lets you look at this webpage. They are engineered to be lightweight and to run on battery power, so they don't typically use as much energy as a desktop computer. When they are unplugged, they use battery power. When they are plugged in, they charge the battery. When they are plugged in and the battery is completely charged, they only use as much electricity as is needed to run the computer. This was an HP Compaq 6910p
Power:This laptop used 47 watts when its battery was fully charged. If the battery was low, and the laptop was plugged in, it would draw 99 watts, 52 watts of which was presumably for charging the battery. When the laptop was off, but charging, the laptop consumes 57 watts.
Power Cost:
at 12¢ per kw/h Cost per Minute: 1 hundredths of one cent (0.01¢) Cost per Hour: 56 hundredths of one cent (1¢) per Day (8 hrs):5¢per Month (5hrs/day):86¢
Wiring system size: 12/24/48 volt
There is a basic rule for deciding on the wiring size:
From 0 - 1000 Wh = 12V system
1000 - 3000 Wh = 24V system
3000 Wh+ = 48V system
Description:A laptop is a small-sized computer that lets you look at this webpage. They are engineered to be lightweight and to run on battery power, so they don't typically use as much energy as a desktop computer. When they are unplugged, they use battery power. When they are plugged in, they charge the battery. When they are plugged in and the battery is completely charged, they only use as much electricity as is needed to run the computer. This was an HP Compaq 6910p
Power:This laptop used 47 watts when its battery was fully charged. If the battery was low, and the laptop was plugged in, it would draw 99 watts, 52 watts of which was presumably for charging the battery. When the laptop was off, but charging, the laptop consumes 57 watts.
Power Cost:
at 12¢ per kw/h Cost per Minute: 1 hundredths of one cent (0.01¢) Cost per Hour: 56 hundredths of one cent (1¢) per Day (8 hrs):5¢per Month (5hrs/day):86¢
Wiring system size: 12/24/48 volt
There is a basic rule for deciding on the wiring size:
From 0 - 1000 Wh = 12V system
1000 - 3000 Wh = 24V system
3000 Wh+ = 48V system
Watts amps volts
Folks often get confused about the correct units in which to measure power consumption. Watts measure power being used or gained at any given instant. But Energy is what's most important to you, not power-- Energy is power measured over time. It doesn't matter that the big TV in your camper uses 200 watts. The real issue is how many hours per day you have the thing on! So, the proper units to use are watt-hours or amp-hours (A/H), not watts or amps. Ten amp-hours of use means that you ran your boombox that draws one amp for 10 hours--or that you ran your big TV that draws 10 amps for one hour. You get the idea.
http://www.otherpower.com/popup.html
http://www.otherpower.com/popup.html
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