Thursday, September 9, 2010

Hybrid Solar

There are a number of ways of defining hybrid solar applications. Some definitions describe combining geothermal concepts with solar heating concepts... other ideas involve the extraction of heat from PV panels since PV systems run more efficiently at lower temps.

My idea of hybrid solar involves using PV power to harvest solar heat... To do this a battery backup system is often involved that uses a charge controler to protect the battery. Some fancy charge controllers have a price tag in excess of $1000, but a simple charge controller used to power a pump used in a drainback system may only require a $10 investment.

Monday, August 23, 2010

Green Energy Tips

Here are a few green energy tips to help you get started on a green way of thinking. Social transformation takes time, but if you on the right path you're already there.

Flow Dynamics

Buckminster Fuller once remarked that many of our social and economic and physical challenges can best be addressed by understanding how nature addresses them. Have you ever wondered how a mighty oak can support the weight of a horizontal limb or how or how a bird can fly or how a tiny heart can pump blood through thousands of miles in of microscopic arteries and veins and capillaries. Sometimes ideal solutions to problems are not practical but they can still supply us with fuel for thought. There is more than enough direct sunlight energy for everyone and yet governments allow the continuous exploitation of non-renewable resources as the quality of life and the health of our tiny planet declines. We do have alternatives but if we are to live in harmony with nature we must learn to understand the nature of nature. All animals from the microscopic ameba to the to the macroscopic sperm wale have have some kind of circulatory system that makes life possible by transporting food energy, nutrients and oxygen. Most multicultural organisms are equipped with a heart that circulates oxygenated blood through a parallel network of capillaries. If the surface area of a person 1'x1'x6' could be spread out with a thickness of .1" their surface area would be 720 sq ft. The surface area of a solar collector this large, operating at an efficiency of 50% could harvest the heat energy equivalent of 108,000,000 BTUs per year... with a street value in excess of $2000.

This natural method of circulating fluids through a large parallel network is sometimes known as branch connected plumbing. Small hearts with low energy requirements can support large organisms with this method of blood distribution. Unfortunately full blown branch connected solar plumbing systems are not cost effective when it comes to collecting and storing the sun's heat energy.

Tuesday, August 10, 2010

Ray of Hope

Today the oil-stained tides are turning on the oil stained oilrigs. More and more green people are jumping on the DIY solar bandwagon. PV installers are available for those willing to make long-range investments. AND DIY people, capable of doing the work, are making cost effective, practical investments in solar heating systems.

Fortunately most of the materials needed for solar heating systems are still commonly available. In 1980 I worked with the Adirondack Solar Association to help people make collectors and other solar applications from commonly available materials. After the Oil Embargo in the mid 70’s the alternative energy industries started to blossom, but fragile new green businesses were stomped out when Reagan killed Carter’s “Solar Bank Bill” in 1980. The Alaska pipe line and other well drilling operations soon brought the price of oil back down so people soon lost interest in alternative energy resources.

Unfortunately drilling our way out of the energy crisis does not work. The made race to capitalize on our planets rapidly disappearing oil resource causes catastrophic injuries to our fragile environment. Hazel Henderson, an economic advisor for president Carter, was also the author of “Dawn of the Solar Age”. She compared the oil companies and other large corporations to dinosaurs. Mrs. Henderson said they are all headed toward extension and we should step aside when they begin to fall. For this reason I believe bailing out extinct dinosaurs and attempting to stimulate dead or dying industries is a mistake.

Hopefully the Obama administration will at least be able to stand firm on the issue of the offshore drilling moratorium…. AND hopefully the bridge between green energy awareness and green energy jobs will be built. Social transformation is a slow, painful, difficult process and many will not adapt… But we should all accept the natural evolutionary process as a condition of life.

As the polar icecaps continue to melt, and as world temperature and world population continues to rise the jobless find themselves at the crossroads of a social revolution. We are all on the endangered species list and it may be too late to reverse the global warming and global pollution trend. We have never been on top of the food chain and in charge of nature and we are only a small part of the universe and our inability to work in harmony with nature may soon be challenged. If we are to survive as a species we must listen to our inner voice of truth and understanding and find a way to connect with the world around us. We do have alternatives but we need to stand together and turn those alternatives into practical social and economic solutions. All we have to do is read the writing on the wall and take actions based on understanding rather than media manipulation. There is still a ray of hope.

Friday, January 1, 2010

Solar Heating

Passive solar greenhouses and modified, passive Trombe Walls can also supplement some of the heating needs of a home, but air is not a good heat transfer medium and the heat from air is difficult to store. If you decide to stick with a passive solar air heating system and you live in a cold climate with limited sunlight be sure to have a back up heating system. I prefer water to air when considering heat exchange systems, but a combined air and water system could work in harmony.

What’s so great about water anyhow?
Well, water has a high heat capacity and a good heat transfer rate. It’s also plentiful, inexpensive and non-toxic.

Great! That answers a lot of my questions but what is heat capacity.
Oh that! Heat capacity is the measure of the energy required to raise the temperature of a substance. For example it takes one BTU of heat energy to raise one pound of water one degree F. Water is a substance that has one of the highest heat capacities. An equal volume of water can hold about 2,000 times as much heat as an equal volume of air so water is an ideal low cost, safe substance for storing and transporting heat.

OK, OK I get the idea. Water is a substance of choice for storing and transferring heat, but doesn’t water freeze?
Yes water freezes, but freezing is not a problem with trickle down or drain back systems. Water simply drains back into the storage tank when the pump is turned off. There is no need for a pressure relief valve or check valve. The plumbing is simple and antifreeze is unnecessary.

OK, Let’s say that water is a great heat storage medium. How much water will it take to heat my house in Maine?
Generally speaking you’ll need at least one gallon of solar heated water for every square foot of living space. You’ll also need the entire surface area of a properly oriented steeply pitched roof to harvest solar heat.

Sounds good but I have a problem. My ranch roof faces East.
This is a problem. You’ll harvest less than half as much heat from an East facing roof as a South facing roof If you decide to add a second floor take the time to pitch the roof in the right direction.

OK if I have a 1000 sq ft roof pitched in the right direction what will be the value of my heat harvest per year?
Well this depends on a number of factors but let’s give the calculation a try. If you have 1000 sq ft solar roof and an average of 3 hrs of sunlight for 300 days you’ll have about 300x300x1000 BTU’s of available solar energy. At an efficiency of 50% you’ll be able to harvest 45,000,000 BTU’s of heat per year, or the heat energy equivalent found in 300 gallons of fuel oil. If we assume that the value of fuel oil is $3.33 the value of this much energy would be about $1000 per year. This might not sound great but as the value of fuel increases so will the value of the solar heating / hot water system. As long as we keep the initial cost down our investment will pay for itself in a short time.