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Posts Tagged ‘electricity’

According to an article IBM has designed a dish to concentrate sunlight onto Photovoltaic cells keeping them cool using water. Ahhh, maybe people have a really short memory but this is nothing new. Moving onward….

My preference is sill using a dish to focus sunlight onto a stirling engine which gives and impressive 25-35% efficiency in converting sunlight to heat and electricity with far less effort. Stirling engine also last a fairly long time with little maintenance. What IBM is proposing is good for areas with water or that could use the dish to desalinate water but not in a desert, but stirling engines with concentrating mirrors are perfect.

I’ve now been unemployed coming up to 2 1/2 years and I am finding new freedom in the lack of work. I just have to get use to being so poor.

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The Sun has been a source of inspiration and awe for a very, very long time. It can not be known how long ago people noticed that the Sun can warm the body or where a person lived but it can be safely said that it was well before any written language.

Solar Heating has been around for almost as long as we have build dwellings to live in. Here in Colorado we have Mesa Verde cliff dwellings that used the sun to keep warm in the Winter and cool in the Summer. These dwelling made use of Passive Solar gain rather than actively harnessing the Sun’s energy by building their homes in a cliff niche.

Around 400 BCE the Greeks made use of  Passive Solar Energy by constructing their buildings to take advantage of the free heat the Sun provided and when glass was invented used windows that kept the heat gain indoors for a longer period.  A quick timeline of the use of Solar Energy:

  • 3rd Century BCE Greeks and Romans used mirrors to concentrate the Sun’s energy to light torches and fires.
  • 2nd Century BCE Greeks used mirrors to set fire to enemy ships.
  • 20 CE a Chinese document talks about using mirrors to light ceremonial fires.
  • In the first 4 centuries of the Common Era Romans used large south facing windows to help keep bathhouses warm.
  • 6th Century CE the Justinian Code gave everyone right to the Sun and equal access – no one could block another’s access to the sun
  • 1200 CE cliff dwelling like those in Colorado made use of south facing dwelling to harness the Sun passively.
  • Horace de Saussure in 1767 created the first solar box collector used by Sir John Herschel in South Africa to cook his meals.
  • 1839 Edmond Becquerel after immersing two dissimilar metals in an electrolyte found that when exposed to the Sun produced more electricity thereby discovering the photovoltaic effect.
  • …and the number of discoveries only accumulate too numerous to list here.

Although not complete it gives someone the insight that harnessing the Sun’s energy (namely heat) has been something we has been done for a very long time.

Using the sun to cool on the other hand is a newer idea.  The idea first started with Michael Faraday (1791 to 1867)  who was the first to suggest and use a liquid that when allowed to vaporize cooled. The liquid he chose, and which later became used wide spread in early refrigerators, was ammonia. After compressing ammonia it was allowed to vaporize which gave the cooling effect he was looking for, and was the start of cooling and refrigeration.

In a solar collector system the Sun’s heat is used to bring a liquid to a boil and as it vaporizes it giving the same cooling effect without a compressor. Currently there are two types of solar cooling devices on the market. The first makes use of the traditional compressor driven by electricity from a Photovoltaic panel to create the cooling process. The other model makes use of evaporative cooling or absorption chillers.

Another way I recently found that comes out of Germany is the use of traditional Solar Heat Absorption Panels and Photovoltaic Panels. Both provide energy to the home year round. The heat first goes into a tank to be stored until needed. Once the tank is fully charged the heat energy is not ignored or wasted but instead a heat pump is used to move the extra heat into the ground beneath the home to store it. It is a kind of heat battery except slightly more efficiently. To heat the home the Sun’s energy can be used directly, or the heat in the tank and finally the heat stored in the ground. To cool the home a second heat pump is used to draw heat from the house which is then moved directly beneath the home for storage.  This set up, and this is from what I have gathered and has not been fully tested for any length of time as far as I know, is far more efficient than running air conditioners or chillers and direct heating in the winter. This method is called a Geosolar system.

Because the ground is used as both a source of heat and to store excess heat the whole system becomes more efficient.  The big issue with possible freezing of the ground which can happen as more heat is drawn out than is available is eliminated by putting heat back into the ground in warmer months.  Because both the heat source and electricity come from a renewable source of energy the efficiency of this system is in the neighborhood of 500%. That means you are getting more out than is being put in as with a traditional ground based heat pump which ranges from 200 to 300% efficiency. Not bad when a system like this is combined with a PassivHaus design that already has greatly reduced heating and cooling needs to begin with. With a PassivHaus such a system would actually become a secondary backup source of heating and cooling adding to its overall efficiency.

With a home and a system that are both with such high efficiency will allow it to last much longer than a traditionally designed system used only  for supplemental heating or cooling needs. Combining technologies is the answer because each efficiency is piggy backed on adding to the overall efficiency of a system.

Resources:
http://en.wikipedia.org/wiki/Geothermal_heat_pump
http://www.heliossouth.com/documents/Brief%20History%20of%20Solar%20Cooling.pdf
http://www1.eere.energy.gov/solar/pdfs/solar_timeline.pdf

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I am going to use the word Geothermal to mean more than the narrow definition of just producing electricity which many people think of when they hear the word.   Geothermal to me means ‘ground heat’ or heat from the Earth broadening its application.

Background and History

The word Geothermal has its root in Greek words for Earth and Heat. Geo or gaia means Earth and thermo or therm for heat or warmth.  Heat from the Earth has been known for a long, long time with many ancient people making use of thermal springs that naturally rose to surface. Some of them were enclosed to hold in the heat and create a hot pool in which to bath while in other areas the water would have been hauled a short distance for use. Ancient people used this form of Geothermal heat for bathing as far back as ten-thousand years.

It was not until more recent years that we have seen the use of the Earth’s heat to produce electricity.  July 4th 1904 the first power plant using dry steam from a geothermal source went online to produce electricity in Larderello Italy. In 1911 the plant was upgraded to industrial levels for higher electrical production.  It was the only power plant in the world producing electricity in this way until 1958.  The site has seen more than 30% drop in steam pressure from its peak in the 1050’s.

In 1958 the Wairakei plant in New Zealand made use of flash steam technology.  Pacific Gas and Electric began to operate a Geothermal plant in 1960 in California. A binary cycle plant was put into use in Russia in 1967 and in the 1970’s in the United States after the energy crisis. The binary cycle plant makes use of much lower steam pressure. Now there are some 60 plants world wide producing electricity.

Many of the newer power plants make use of wells drilled to pump water underground before it resurfaces as steam unlike older plants which made use of areas where steam naturally rose from the ground.

Some Pro’s and Con’s

Pro’s:

  • compared to fossil fuels it is environmentally friendly and less polluting
  • it is a safe form of energy
  • for the most part it is renewable for as long as the Earth’s core remains intact producing heat
  • it can produce electricity at a fair price and is not subject to price fluctuations as fossil fuels are
  • it costs little to operate a Geothermal power plant
  • it reduces our dependence on fossil fuels and can be a transition energy source to include other renewable energy sources
  • more energy can be extracted by using the remaining heat in conjunction with Stirling engines to produce more electricity or for heating in nearby homes or businesses thereby getting a bigger return

Con’s

  • it is costly to setup a Geothermal plant
  • the heat source does not last and begins to decline soon after a power plant goes online
  • is not available everywhere, very localized
  • it could release poisonous gases like hydrogen sulfide which is hard to deal with or dispose of
  • pipes can become clogged with mineral deposits shutting a plant down
  • Earthquakes and after shocks can occur do to the drilling and pumping of water underground
  • it has limited applications, heat and electricity production only

There is only one Con I can see that is never adequately discussed – is there any potential damage it could cause to the Earth’s core by extracting ‘too’ much heat at one time like if there were too many Geothermal plants built around the world to meet future energy needs. All the water pumped underground to extract the Earth’s heat could cause a cooling effect as has been seen with existing power plants where steam pressure is lost overtime as the heat in the area is lost.  Until this majorly important question is answered without a brush-off with words like, ‘there’s plenty of heat, it can’t happen’ I can not in all honesty support it as a ‘major’ energy contributor and only see it on the sidelines.

Now onto a way I am fully supportive of.  In Europe new home designs with a heat pump work in two ways have been used successfully for a number of years now and should in my opinion be used in the U.S. too. I will admit I have not absorbed all the information as I am not an engineer or scientist to fully understand the inner workings but I do know  enough to relay the information for you here.

First, the home is super insulated to make best use of the heating and cooling without wasting energy as typical McMansions or other low insulation construction methods do.  The home will have several solar panels to collect the Sun’s heat throughout the day storing excess heat in one or more tanks in the basement.  Once the tanks are fully charged the excess heat is not wasted but stored in the ground beneath the house using the heat pump.  When heat is needed it is extracted from the tank and then from underground.  In this way you maximize the amount of heat stored without wasting it.  In summer months the heat pump can act as a means of cooling a home by storing the heat underground for cooler months.  In new homes radiant heat can be installed in both the floors and walls but in older homes the old fashioned radiators or baseboard radiators can be installed.

By combining Solar Heat collection and heat pumps that make use of the ground beneath a home as storage and extracting the heat the whole system becomes more energy efficient with very little need for additional or backup heating or cooling. The ground essentially becomes a heat battery that is recharged part of the year and drawn from when needed. Makes sense to me.

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