This side of the adventure fascinates me. Firstly because I'm learning so much about what electricity is and how it works. My only experience of the terminology, before reading up, was AC/DC - in the context of there being a Highway To Hell and hitting the sack, whilst being Back In Black. Secondly, at our present house the electricity bill has reached such epic proportions, it has overtaken every other 'bill' and now stands at £130 per month. bearing in mind that our water heating system is powered by Oil (at another £65 per month); this seems outrageous.
At the Croft, things are going to be somewhat different... OK, we'll have to be more careful about what we turn on and off, and do we really need this and that gadget, to live a nice comfortable life etc. But this will be good, both for us and for the planet. Checking one's energy usage should be an essential part of life nowadays, and we have been culprits of not doing this; up until now.
Of course, the upshot of this is that we will have NO electricity bill at all! That's right, all of our electricity will be generated for 'free'. With a little work and routine maintenance, the Sun, the Wind and the Water will generate it for us. We are very lucky, in that all of these elements are in place already, at the Croft. It would take quite a large (but very worthwhile, in the long term) investment, for someone to buy and implement these things, from scratch, all at once.
Below I have outlined the three different methods we are employing, in our energy generation, and a brief overview of the technology involved. And for you electricity geeks out there, the power 'stats' these items should generate for us; based on the information I have been given.
Firstly there is a set of four Photovoltaic Solar Panels, rated at 125w each. These generate DC electricity, that charges a bank of eight batteries (similar to 'leisure' batteries, in motorhomes), which, in turn, feed into a Studer Pure Sine Wave Inverter. This little box converts the electricity to AC - the type needed for household use.
But how does this work? Well, NASA explains it far better than I could...
"Photovoltaics is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.
Solar cells are made of the same kinds of semiconductor materials, such as silicon, used in the microelectronics industry. For solar cells, a thin semiconductor wafer is specially treated to form an electric field, positive on one side and negative on the other. When light energy strikes the solar cell, electrons are knocked loose from the atoms in the semiconductor material. If electrical conductors are attached to the positive and negative sides, forming an electrical circuit, the electrons can be captured in the form of an electric current -- that is, electricity. This electricity can then be used to power a load, such as a light or a tool.
A number of solar cells electrically connected to each other and mounted in a support structure or frame is called a photovoltaic module. Modules are designed to supply electricity at a certain voltage, such as a common 12 volts system. The current produced is directly dependent on how much light strikes the module."
All the Croft's water is gleaned from a spring and fast flowing stream, and is collected into two 1,000 litre tanks. As well as for drinking and bathing, water can also be used for electricity generation, if its flowing fast enough, or is under enough pressure.
So, located at the optimum part of the stream, and fed by pipes coming from it, there's also a Pelton Mini Hydro Wheel Turbine, rated at 120w. This too, is fed into the batteries as DC, ready to be 'inverted'. It works in a similar way to the old water wheels, which were used for grinding flour in mills. But the shape of the 'wheel' was honed, by Lester Allan Pelton in the 1870's, to make it more efficient.
A Pelton wheel extracts energy from the momentum of moving water, as opposed to using the water's weight like a traditional overshot water wheel (i.e. the mill wheel). Again, I'm going to defer to greater minds than mine, here. This is how Princeton University explains it:
"Although many variations of impulse turbines existed prior to Pelton's design, they were less efficient than Pelton's design; the water leaving these wheels typically still had high speed, and carried away much of the energy. Pelton's paddle geometry was designed so that when the rim runs at ½ the speed of the water jet, the water leaves the wheel with very little speed, extracting almost all of its energy, and allowing for a very efficient turbine.
The water flows along the tangent to the path of the runner. Nozzles direct forceful streams of water against a series of spoon-shaped buckets mounted around the edge of a wheel. As water flows into the bucket, the direction of the water velocity changes to follow the contour of the bucket. When the water-jet contacts the bucket, the water exerts pressure on the bucket and the water is decelerated as it does a "u-turn" and flows out the other side of the bucket at low velocity. In the process, the water's momentum is transferred to the turbine. This "impulse" does work on the turbine. For maximum power and efficiency, the turbine system is designed such that the water-jet velocity is twice the velocity of the bucket. A very small percentage of the water's original kinetic energy will still remain in the water; however, this allows the bucket to be emptied at the same rate it is filled, thus allowing the water flow to continue uninterrupted. Often two buckets are mounted side-by-side, thus splitting the water jet in half. This balances the side-load forces on the wheel, and helps to ensure smooth, efficient momentum transfer of the fluid jet to the turbine wheel."
Lastly, and in my opinion, most impressively, we will utilise a Wind Turbine. This is 3m high (check out the photo at the top of this post) and rated at 800w. I think this generates AC straight into the house.
The reason for this being my 'favourite' is that the Turbine was hand-built by the people of Scoraig, under the guidance of Hugh Piggott. Many residents have one of these and the community gets together and constructs/erects them, with each other. Hugh also gives courses, in the construction of these beautiful pieces of (electricity generating) sculpture. One of his workshops is happening at the end of April (2014) - details at the end of the post.
You can find much more information about Wind Turbines, over at Hugh's web site. But here is a simple overview, I found at the US Department Of Energy web site:
" Wind turbines operate on a simple principle. The energy in the wind turns two or three propeller-like blades around a rotor. The rotor is connected to the main shaft, which spins a generator to create electricity. Wind turbines are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more above ground, they can take advantage of faster and less turbulent wind. Wind turbines can be used to produce electricity for a single home or building, or they can be connected to an electricity grid for more widespread electricity distribution."
I just assumed that, being off grid completely, someone in our situation, would be excluded from this type of 'perk'. I was under the impression that there needed to be some kind of physical connection. But through the very knowledgeable and informative forum (mentioned above), I have been put right:
"I know its called the Feed In Tariff, but you don't actually have to feed into the grid. So off griders can still get the FIT. You do still have to meter your production and, at this time, there are no DC approved meters; so you have to convert the Solar PV DC to AC, meter it, then convert it back to DC, to charge the batteries, before it then gets stored or used, after again converting it back to AC. Stupid, I know, but, until there is an approved DC meter, its how it has to be."
Well, I hope this has given you all more of an idea of how we'll 'power' our place. It would be great to think that it may have inspired you to look into different and alternative forms of energy generation (if you haven't already); that are less polluting and impactful, on both the planet and your pocket. Then we'd be able to ask: Are Friends Electric?
Here are some links, where I obtained some of the content above, and for further reading, if this topic interests you...
Viable Self Sufficiency Forum:
VSS Forum Index/Eco Stuff
US Department Of Energy:
Scoraig Wind's Workshop: