self sufficient life

Almost free heating

We have found the perfect home and can’t wait to start moving. The place is currently empty, so we could have moved in when we first saw it 3 weeks ago. All the paper work, however, takes time and real-estate agents and bankers who are on holiday make the waiting time even longer.

I’ve been doing some thinking on space heating and DHW heating for the place. The property contains a big greenhouse complex consisting of 8 greenhouses, totaling over 6000 square meters. We wanted a big greenhouse, but this is way more than we are going to use. When checking out the place, one of the greenhouses had all its windows closed and it was unbearably hot in there. This got me thinking, the property has a huge heating system, which is designed to heat all of the greenhouses. The space heating for the house is just t-ed off of the big heating system, but since we are not going to use much of the greenhouse space to begin with, firing up this monster heater just to heat the house would be a big waste.

What if we can store the heat from the greenhouse for later use? One greenhouse would just function as a huge solar panel with water flowing through tubes and back to a big heat storage tank. A 20.000 liter oil tank, which is already there, can probably be used as the heat storage tank. I would only need to insulate it and run some pipes from the greenhouse to the tank.

I have no idea how much the greenhouse will heat up on a sunny winters day, but I will probably need some supplemental heating. If you have a big heat storage tank, you can use several heat sources to feed it. I will probably install a wood burning stove right next to the heat storage tank, to ensure we don’t freeze in winter. Heat generated by a Lister engine can also be fed into the same heat storage tank.

I found builditsolar.com to be a great resource on DIY solar projects. If you want to know more about wood stoves for heating, you should check out the forums on heart.com

Solarpower Breakthrough at IBM

You probably know how you can use a magnifying glass to concentrate solar power into a small spot and start a fire. The solar power researchers at IBM have taken it a step further and managed to concentrate incoming solar energy by a factor of 2300, equaling about 230 watts of power on a square centimeter. This energy could then be converted into about 70 watts of usable electric energy. The biggest problem with concentrating the suns rays this much is that it heats the solar cells to about 1600 degrees Celsius, which would melt them. IBM however is an expert at cooling high power computer chips and managed to keep the solar cells at a ‘cool’ 85 degrees Celsius!

Read IBM’s press release here

Free solar heating

There is a lot of free energy coming our way each and every day, all we have to do is convert it to some usable type of energy. I’m talking about solar energy of course. There are a few ways we can use the energy packed rays that the sun sends down to us.

We all know about solar panels that convert light into electricity, the major problem with them however is that they are quite pricey and not very efficient. We can also use solar power to heat water in a simple to build solar water heater. The hot water can be fed into your central heating system to help heat your house or tap water. This energy will not be completely free, as we need some electricity to run a water pump so the heat will be transported from the collector to where we need it.

But there is another way we can use solar heat to heat up our house and it is completely free after setting up this simple device! All we need is some timber, a corrugated black sheet of roofing sheet and a transparent sheet of plastic or glass.

Start by making a wooden frame and attach it to your outside wall. You will have to use a south facing wall (or north facing if you live in the southern hemisphere) for this to work. Within the wooden frame you have to cut some holes in the wall, so air can circulate between the house and the solar heater. The holes will be placed at the top and bottom of the frame. You can make the whole thing as big or small as you want. Ideally you want to cover your whole south facing wall, the part that doesn’t have any windows that is.

Next the black corrugated sheet of roofing will be screwed against the wall. The black color will help in converting the incoming sunlight into heat. Black works best because it absorbs the complete spectrum of light rather then reflecting some wavelengths like colored objects do. Once the sheet has been heated up by the sun, it will heat up the air around it. It will stay warm for a while when the sun is not directly shining onto it. This makes the solar heater have a somewhat constant heat output even on days with some clouds.

All that is left to do is adding the clear plastic or glass cover. Make sure that there are no gaps between the wood and the cover (or the wood and the wall) or heat can escape and cold wind can enter the solar heater (and your house) That’s all there is to it, you will now get some free heating when the sun shines! How come we don’t need any fans to move the air? This is simple physics: as the air is heated it will expand and move up and through the gaps in the top of the heater. While doing so, it will pull in cold air through the bottom gaps which will be heated up by the black sheet and continue the cycle.

Heat and power, power and heat

In Europe, Canada and the US, the power companies are required to buy back any excess energy you create. The rates, at which they buy back the energy, depends on a few things and the rules are different in each country and state. You can get detailed information on this subject from your utility company.

Solar energy, for instance, will be paid at a higher rate than power generated with a diesel generator because it is obviously much cleaner energy. In Europe you will also get a better rate if you burn vegetable oil instead of diesel, but you will have to show proof of the origin of your oil, so waste vegetable oil collected from restaurants will not get you the higher rate, although the collected oil will be cheaper than buying new vegetable oil, possibly still making it an interesting alternative on the bottom line.

The amount of energy you can sell back also differs from each power company to the next. While some will buy back as much as you can generate, others will only buy back as much power as you buy from them, effectively leaving your power meter at the zero mark.

Since we are currently looking for a new house, I don’t know which power company we will be dealing with. Assuming, for now, that I can only sell back the amount of electricity that I use, generating our own power will not bring in any money. After working out the fuel usage for the generator and assuming that I have to buy vegetable oil to run the generator, plus the generators initial purchase price and ongoing maintenance, the bottom line is that the power from the utility company will cost about the same or maybe even a little less.

However, the electricity is not the only thing I will be generating. A big part of the energy will be lost as heat. Lost if you don’t catch it, that is! Running the engines cooling water through a heat exchanger in the central heating system will have a positive effect on the total fuel consumption of the central heating.

The whole thing can also be turned around: so, instead of running an engine to cover your power needs and use the excess heat to complement your central heating system, you could also have the engine running to generate the heat to warm your water and house, while running a generator head along side to create electricity while you are heating. Sure, ultimately we are talking about the same system, that generates heat and power, but the sizing of each system would be different.

How our system will be sizes isn’t decided yet. We will first have to find a suitable house. Depending on the age and condition of the central heating system, we will then go one way or the other.

Generate your own power

I dug up some old electricity bills the other day to check how much juice we have been using over the past few years. I was shocked by the numbers I found, we use about 10500 kWh a year which equals a constant load of (10500 kWh / 365 days / 24 hours =) 1.2 kW or 1200 Watts. The power usage itself isn’t the shocking part, considering we use electricity to cook on, have a bunch of other appliances that are used regularly and a few tropical aquariums, one of which is a saltwater aquarium which has some quite powerful lights and pumps. What did shock me was to see the total money spend on electricity. With a kWh costing about 24 cents, the total yearly cost for our electricity usage ads up to 2.5 grand (that is Euros, which equals about 3,700 US$!!!)

There are better things to do with that kind of money but we still need the electricity. Sure, we can probably cut down on usage, but quite frankly there are not a lot of electric comforts I want to give up. I will use an average of 1000 Watts of power usage to figure out what kind of power plant we need to build. If I take into account the small fish farm we might want to start, that adds another 1000 Watts.

I’ve already ruled out solar power because the up front costs will be too high. I do want to tap into the power that the sun delivers for free, but I will use that for heating instead of electricity generation. Wind power is another free source, but since it depends on the weather conditions I’m not too keen on that either. I will probably experiment with wind power in the near future but for now I need a better, more constant, source.

I am having a closer look at Lister-engines and the more I read about them, the more I like them. A Lister CS (cold start) engine is a diesel engine that can deliver great power for very little cost. These engines are build to run for decades, I’ve read about some that have been running 24/7 for over 40 years! And the required maintenance is very low. These engines run at low speeds of 600 – 1000 RPM, making them less noisy than regular diesel generators.

Running an engines like this hooked up to a 10 kW power generator for about 5 hours a day would be able to cover my total power consumption. The heat generated by the engine can be fed back into the central heating system. Using the generated heat would be another big money saver considering the huge increase in oil prices, currently at $95 a barrel vs. $52 per barrel in January! The oil price does not affect the running cost of the generator as it can run on waste vegetable oil, which can be collected from local restaurants for free. The restaurant owners normally have to pay to get their used cooking oil disposed of.

Since the electricity generated by the generator would be somewhat constant while it is running and the usage has spikes as appliances get turned on and off, a buffer is needed to store the generated power, so it can be used at times when the generator is not running. One way to store your electricity is in batteries, but since most homes here are connected to the electric grid, we can just use that! Solar systems are often hooked up to the grid like this, by using a special electricity meter you can have the meter run backwards when you generate more power than you use. If we feed enough power back into the grid we can start sending bills to the power company, much better than receiving their bills!

Catching the sun

One freely available green energy source is the sun. It shoots its power-packed rays at the earth every day, all we have to do is catch them and convert that energy into a form that is usable. Solar panels that convert the sunlight into usable electricity cost a lot of money. They do pay off in the long run, but the up-front costs are just too high for us. There are other ways to use solar power though.

I am looking into using the suns power to heat our water. A solar water heater can be home-made for a fraction of the cost of a commercial unit. The design and construction doesn’t require any special knowledge or tools and the materials needed can be bought at any hardware store. What we have to make is a big box, with a glass (or plastic) top that allows the sunrays to enter. The inside of the box is painted black because black absorbs most of the light (and heat!) Sound familiar? What we have is basically a solar oven. Now all we need is to run our waterline through it, so the water can absorb the heat. To give the water passing through the heater time to absorb heat it should flow at a slow rate. We can easily slow down the flow rate by dividing the total flow with a manifold and using a second manifold at the exit to combine the different pipes again.