One of the biggest issues that we seem to face in shifting our attention from traditional fossil fuel based energy systems to alternatives appears to come from our expectations of change.  For thousands of years mankind has experienced minimal and gradual change.  Major improvements were things like the wheel, the plow, and the printing press.  For extended periods very little changed.

            &nb sp;  Since the Renaissance our pace of change has moved at an ever accelerating pace.  Alvin Toffler’s “Future Shock” written in 1970 is now a classic and during the intervening 40 years our pace of change has become even more accelerated.

            &nb sp;  One place that change has been most rapid in is technology of computers and graphics.  These serve to propel our imaginations into virtual worlds which are far removed and different from the one we live in.  They also lead us to believe that new technologies for producing energy, transport, and food are just around the corner and about to happen.

            &nb sp;  The reality of things is far different.  While our researchers continue to toil in their labs and in the field to find new and innovative ways to do things we are still constrained by the rules of Physics and nature in this world.  So while we see ideas on our computers and televisions in which we have unlimited power from tiny pollutionless units or the ability to teleport from point to point we have to return to the reality of our world when we are done.  

            &nb sp;  Our current primary source of power based on fossil fuels is that way for a good reason.  Over millions of years plants have been turning solar energy into the mother of all concentrated power sources.  One gallon of gasoline can do the physical labour of a man can in 44 hours.  One gallon of gasoline is equivalent to 55 gallons of liquid hydrogen.  It is a truly remarkable source of power, only exceeded in its sheer capacity by nuclear sources.

            &nb sp;  Since most solar and alternate energy sources are not able to be harvested sufficiently to replace what we are using they seem to get short shrift most of the time.  I would suggest instead that we look at these alternatives as ways to augment or reduce our current fossil fuel energy streams.  An average Florida home consumes about 80 KwH of electricity per day.  Florida does not have the steady driving wind necessary to reliably generate power but we do have a lot of sunshine.  For the purposes of generating electricity through photovoltaic (PV) systems, humidity, heat, panel orientation, dust, and clouds significantly reduce output.  If we ignored the concerns of storage and conversion from direct current solar electricity to usable house current alternating current you would still need a tremendous area of panels.

            &nb sp;   An 85 watt panel generates about enough power to run a 60 watt light bulb and costs $450 or more.  It also requires 7.25 square feet of open space.  Assuming 6 hours a day of rated power production this unit will produce 360 watts of power, or 0.36 KwH.  To replace the entire power consumption of the home would take 222 panels and cover an area of 1,609 square feet, assuming an average of 6” around each panel for access and maintenance brings our square footage of the array up to 2,275 square feet, probably bigger than the house itself!  This system that would just be sufficient to meet the home’s needs at a cost of over $130,000 or $0.23 per KwH for twenty years to pay for the system.

            &nb sp;  This quick exercise in mathematics should be sufficient to show that stapling a few solar panels on the roof will not eliminate your power bill.  This is where most people stop.  This is also the point at which we have to look again and press forward.  Our current focus in energy should be based on cost value and return on investment.  A solar hot water system should eliminate about 80% of your power consumption for generating hot water.  Some electricity is still used to boost temperature on cloudy days, here in Florida these supplemental systems rarely kick in.  A hot water system can cost as little as $3,600 for a full system, less if you have some usable equipment in place already like a large hot water tank.  This replaces 16 KwH per day of electricity, a pretty big chunk of that daily 80 KwH.

            &nb sp;  Beyond hot water there are now significant reductions and savings available by employing multiple incremental changes.  Window tint, Energy Star appliances, programmable thermostats, etc. can all be combined to push the total energy consumption down toward the 40 KwH per day area, half of the current use.  All these improvements not only reduce your power consumption and electric bills, they also make significant reductions in pollution.

            &nb sp;  The real impact of this can be seen when you consider the Annual Energy Review 2008, this graphic representation of energy sources and uses compiled by the Energy Information Administration puts our energy use in perspective.  Residential power use 21.64% of our overall energy consumption nationally.  If we reduce that by 50%, an achievable goal without huddling in caves by firelight, we could eliminate nearly 50% of our coal consumption or 40% of our petroleum imports. 

            &nb sp;  These are not numbers or ideas based on future breakthroughs, exotic systems, or major lifestyle changes; they are the application of existing, proven technology that can be easily installed in every home.  The majority of these changes could be achieved for under $8,000 per home and would pay for themselves in 3 years.  They are not as sexy and exciting as the prospect of showing your neighbors your new windmill but they do work today and have significant, uncontestable results. 

            &nb sp;  We have to make these things a priority or they won’t happen.  Consider borrowing to make these improvements, unlike putting tonight’s dinner on the credit card these will improve the value of your home, pay you back for the money you spent, and give you the satisfaction of knowing that you are making the steps that will help us all live in a balanced working world that can continue to rise to greater challenges in the future.  Our leadership is crucial in this process.  If we don’t begin to make these adjustments on our own they will eventually be dictated by the government resulting in reduced choice, higher prices, and more loss of freedoms.

Tags: Solar-energy Solar-efficiency

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            &nb sp;  Our modern world runs on heat, while this idea may seem odd at first let me explain.  Automobiles operate with heat, the expansion of burning fuel in the cylinders acts to create both mechanical motion and heat as a waste product.  When the car is stopped the action of the brakes converts the motion to heat.  Electricity run through an incandescent light bulb creates light from heat as well as heat.  When the light is absorbed by the objects it falls on this also creates heat.  Stand under a stage light for a minute or two and you will get an idea of how much heat a light can generate.  An electric motor uses electricity to rotate a driveshaft resulting in heat and motion, the motion will also be resolved as heat in the end.

            &nb sp;  In our homes and businesses we consume a large amount of energy moving heat around.  The refrigerator or freezer uses its system to move heat from inside the box to the outside, in the process dumping heat into the surrounding space.  Lights, stoves, televisions, chargers, computers, everything that runs on electricity, add to the heat inside the space when that electrical energy is converted to work.  We then operate air conditioning equipment to move that heat again so that it is outside of the space. 

            &nb sp;  Transformers also generate a large amount of heat.  The process of reducing current from the transmitted voltages for transmission systems to what is used in your home incurs losses in the form of heat.  Many commercial buildings have power that comes in at 480 volts which is then stepped down to 240/120 3 phase power.  You can always find these units as they are humming away and somewhere between warm and hot to the touch.  Most of these units are inside the building, belching out heat that then takes more electricity to move back out of the building.  Large transformers aren’t the only culprit.  Computers, phone chargers, power supplies, and the like all use transformers to shift the power to what that equipment uses.  While these don’t churn out the same BTU of heat that a large transformer does, their cumulative affect can really add up.  Most people don’t think about the idea that all these chargers are still using power even if the device is not attached.

            &nb sp;  This could be thought of as unwanted heat, a byproduct of the use of electricity, not the same thing as heat that we generate to keep warm on cold Winter nights.  As air conditioning of space is one of the largest consumers of electricity, as shown in Summer brownouts and spiking electricity consumption on hot Summer days, it makes sense to focus attention on how to reduce heat gain in conditioned spaces.

            &nb sp;  There are a surprising large number of ways to do this which vary from free, maybe involving a little effort, to exotic solutions. 

1.      Turn off appliances and electrical items that are not in use.  Computer equipment such as printers are often left on, idle, generating heat.  Set your computer to go to sleep after a short period.  Put chargers on a power strip so they can all be shut off together.  If you are like me it may take two strips.

2.      Have your windows tinted.  Most windows are not energy efficient.  Unfortunately replacement of windows is hard to justify for energy savings alone.  If you consider this be sure to work the math out until you are sure it is worthwhile.  Tinting the windows will reflect back much of the sunshine that becomes heat once it enters the conditioned space, when reflected it has no effect inside.

3.      Change your lighting.  Light bulbs all have a wattage marked on them, this represents the power used and the heat generated.  Fluorescent, compact fluorescent, metal halide, LED, and other lighting alternatives to incandescent lamps not only use less electricity, they generate less heat and last far longer.

4.      Shade your cooling system.  If your home is like mine it was situated on the lot for street facing not energy efficiency and the cooling system was placed for convenience.  Mine gets blasted with full sun all day, every day.  I spent an afternoon and built a shade trellis for it.  With proper spacing this will shade the unit making it more efficient yet still accessible for maintenance.  Plant a deciduous vine on it and enjoy it during the Summer.  In heating months the leaves fall off and the vine is trimmed back allowing the sunshine to reach the system again.

5.      Fill your refrigerator and freezer fully.  Air is hard to cool and keep cool, plus it falls out of the fridge when you open the door.  Cold air sinks, warm air rushes in to take its place.  By keeping your icebox full the mass of the items inside stay cold when you open the door resulting in more efficient operation.  It is also useful to let items to be refrigerated cool to room temperature before putting them in the refrigerator.  This lowers the work done by the cooling system and minimizes the addition of humidity as well.

            &nb sp;  These are some simple ideas which cost very little.  Tint and lighting can be DIY projects as can a shade if you are handy.  These are the first steps on the road to being green.  None of them require much effort or a change of lifestyle but they will affect your utility bill without costing an arm and a leg. 

            &nb sp;  Please feel free to share your comments and experiences so that others may benefit from them.

            &nb sp;  Paul

Tags: Solar-energy Solar-efficiency Solar- HVAC Solar-cooling

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This article is my effort to shine some light on the comparative difference and value of two ways of harvesting solar energy, Domestic Hot Water and Photovoltaics. Don’t hate the conclusions, math doesn’t lie.

The ability to heat water with the sun has been apparent to all of us since the first time we got burned with water out of the hose. This is a basic solar hot water collector. Add some low iron glass, an insulated box, a pump, and a tank, and you have a ready source of hot water every sunny day. Writing from my desk here in Florida, the Sunshine State, I know we see about five fully cloudy days a year. Current systems even have a highly efficient booster which will take up the slack on those cloudy days, you don’t have to skip your shower.

A current domestic solar hot water system won’t even be a noticeable change to your lifestyle. The time it will be noticed is in the average $65 reduction in your power bill, every month. What you won’t notice is that the reduction in greenhouse gas generation is the equivalent to taking a regular car off the road. The average system is about 40-60 square feet of panel.

The cost for this modern marvel of old technology is about $4,300 out of pocket. Tax benefits and grants are available reducing this cost to as little as $2,350. This means that this system will pay for itself in about three years for the average home. If you were to convert this back to electrical generation the average hot water heater for the average family consumes 18 kilowatt hours of power per day, 6,570 KwH per year. If we look at this over a ten year period this means that an initial investment of $2,350 generated 65,700 KwH of reduction in power usage. A rate of $0.035 per KwH, I challenge you to find any utility company who will charge you three and a half cents per kilowatt hour and further expect that utility rates will triple or more in the next ten years making the value to the homeowner even higher. I know that I would buy as much power as I could at that kind of rate!

Unfortunately Solar Domestic Hot Water isn’t exciting. Telling your friends about saving money by making your own hot water has nowhere near the appeal of telling them that you are trying to get off the grid and generate your own power. That you can even sell back excess power to the utility company and they have to pay you! Let’s explore this further.

Photovoltaic systems are based on silicon wafer panels which convert a small percentage of the sunlight that falls on them into direct current electricity. Yes, direct current, not alternating current that we use here. This means that the system must include an inverter, a specialty electronic component that changes the direct current electricity into alternating current for use in our homes. Inverters run about 40% of the system cost on average and wear out in about 8 years having to be replaced.

A PV system I can find online runs $26,000 for the whole system, $3,400 of this is for the inverter. With tax credits this is reduced to $18,200, other incentives are often available. This is a 4.8 KW system, meaning that the panels generate 4.8 kilowatts of power per hour in optimum conditions. Overheating, shading, sun angle, all diminish this output. Conversion to alternating current loses a portion of this power as well, the average inverter reduces power by about 30%, this loss is experienced as heat. Now we are down to 3.36 KwH from the system which you might get for an average of 4-5 hours per day year round.

Daily energy output from the system is then 5 hours times 3.36 KwH or 16.8 KwH per day, 6,132 KwH per year. (Note this is approximately what the Solar Hot Water system was replacing.) If we then apply the same math to this unit as the Solar Hot Water system, we get the following. Over ten years the PV system costs a minimum of $18,200 plus one replacement of the inverter at $4,300, of course the inverter will cost more then but this is already complicated enough. Total cost of $22,500 resulted in a generation of 61,320 KwH of power. The cost per KwH is $0.367, more than ten times the cost of the power replacement by the Solar Hot Water System. Additionally this system takes 350 square feet of space, 9 times the space of the Solar Hot Water System.

Unfortunately this example is pretty indicative of the state of PV technology. Unless the cost of power more than triples, or the components drop to 1/3 their current price, this technology cannot compete at the homeowner level. To further make matters worse, the idea of selling power back to the utility company is like giving it away. They only pay approximately half of the going rate for the power you send them which cost six times that much money to generate.

Sadly for those of us who are excited and want to do something about alternative energy by generating our own power, PV is a solution that doesn’t work out mathematically. Get a solar hot water system and enjoy every shower more. Then put the money you wanted to spend on PV into other efficiency improvements and you will come out far ahead. More on this in my next post, Efficiency Improvement Priorities.
Paul

Tags: Solar Hot Water Domestic-solar-water Solar-hot-water Solar-heating Solar-e

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