Reducing our Personal Carbon Footprint

Mar 12, 2017

How in the period of a little over four years we reduced our personal yearly carbon footprint by about 80%, or by at least 60% including some planned RV trips over the next few years.

In late November of 2012, we contracted with a local Las Cruces, NM Company (Sunspot Solar) to install a 5.1 KW Grid Tie ground mounted Solar Array. It has worked great for us producing about 120% of our electrical needs. The excess power is sold back to the local utility (for 8 cents a kWh) for about eight months of the year and we have a small electric bill in the summer months because of the extra power needed to power our central air conditioning. We net about $400 a year in sales of power per year after the summer electric bills are factored in.

Regardless of popular claims to the contrary we do have to pay for our so called free solar power. It is in the form of loan payment on a second mortgage to pay for the solar array. We did not come out ahead on this because we used the tax credit to install the Central AC and not to pay down the loan. The long term interest charges means the bank in R.I. is the entity that is really making the money off our solar array, not us. If we would have had our own money to buy this array it would be one of the best investments we could make.

This is not the primary reason we had our grid tie solar installed however. The primary reason was to reduce our Carbon Emissions (CO2) for electricity. This one move decision effectively cut our Carbon Emissions in half or by about 9.9 tons per year on average. The decision to install central AC reduced our power needs for air conditioning by about 40% so it was important. It reduced what would have been larger summer electric bills to a more manageable level as well as increasing our comfort.

I had to argue with our AC installer to size only a 3 ton unit as his square footage metric would have dictated that he install a 4 ton unit. The reason for this is that when we built our house we built with 2x6 walls (R-19 insulation) and we wrapped the whole house in ½ inch foil faced foam board which added another R-4 to the building envelope as well as a built in radiant barrier. We knew a 3 ton unit would work because prior to that we had no trouble cooling our house with three window units collectively adding up to only 2 tons but with a lower SEER rating.

This central air installation worked out for us in another way. Prior to the AC installation the crawl space of the house was part of the heating and cooling loop. To make the AC work we needed a more effective air return so we installed the ducting in the crawl space to provide for a proper air return. This meant the crawl space was now isolated from the system and we were no longer attempting to heat and cool it. Since our floor was fully insulated this meant a reduction in square footage and an increase in efficiency.

All of this work was accomplished by the summer of 2013. In the fall of 2015 we became interested in installing a pellet stove for our house so we could reduce the amount of propane we were using. Historical records showed me we burned through about 300 gallons a year for all purposes. We cook, heat water, dry clothes, and heated the house with propane. Our base rate minus the heating was 120 gallons a year or 10 gallons a month.

Propane is rated at 137 lbs of CO2 emissions per million BTU’s. This is a rather arcane way of rating it. Since there are approximately 91,000 BTU’s per gallon this means that 1,000,000/91,000 = 10.98 lbs per gallon. You would not be far wrong to think of it as 11 lbs per gallon. This means we were producing 3,294 lbs per year/2,000 =1.647 tons per year. The pellet stove while by very effective at heating our house is kind of an all or nothing affair not being a device that can be rapidly turned on and off like a furnace. This meant we still rely on the furnace on nights when it was above 40 F as a night time low.

Operating this way the furnace might only come on a couple of times a night for a few minutes. The net result of this was we only cut our propane use in half or by about .82 tons of emissions per year. We did now have a great back up system for our central heating that can be run on battery system if we lose power. We do not have a battery backup system installed yet. The pellet stove only requires .5 kWhs a night so the requirements to build one are not too onerous.

Last year I notice the price of LED light bulbs had decreased by quite a lot and that a larger selection was available. This set me off a journey to replace all the lighting in our house with LED’s. We already had a house full of CFL’s but there were still savings to be had. I was even able to retrofit three 2 tube T-8 fluorescent troffers with LED T-8 direct wire replacements (no ballast) taking them from 54 watts down to 36 watts. Long story short this investment reduced our electrical consumption by around $10 a month on average.

The largest major CO2 producer left for us to address was gasoline consumption for transportation. We had a 2014 Ford XLT pickup truck for all our transportation needs and for towing a 5th wheel trailer occasionally. At 17.8 mpg on average this really was not a fuel efficient daily driver. To add injury to insult we were putting 15K miles on our truck per year which meant by the time we had it paid off it would have over 90K miles on it at least. We were averaging 843 gallons per year at 19.6 lbs of CO2 per gallon = 16,179 lbs per year or 16,179/2,000 = 8.089 tons.

We had a real opportunity here to shift some of our driving over to solar power if we could find an electric drive vehicle to meet our needs. After exploring the issue quite a while I determined that a PHEV would probably work best for us. A BEV (a pure electric car) at 100 mpg-e would still require nearly 5K kWh’s a year and would not leave us much in the way of excess power to sell back to the utility. Worse still we would still have to use the truck for any trips beyond the range of the EV anyway.

We settled on a PHEV a Ford C-Max Energi with 20 miles of battery electric only range. In combination with its 2.0 liter Atkinson Cycle engine could net over 60 mpg in local back and forth driving to town which is 20 miles one way. The way this works is we switch over to EV mode before we get to town, do all our driving around town in EV mode and as much as we can on the return trip home. It turns out so far we are only using from 170 kWh to 200 kWh’s a month for this duty. The 14 gallon gas tank can effectively power us through a whole month only using 13 gallons for approximately 1,100 miles of range if we plug the car in daily. Since we only had a little over three months of data to work with I cannot say with any great certainty what the performance will be over a whole year. From the number crunching I have been able to do so far it looks like we will be able to eliminate the need for 500 gallons of gasoline a year which at 19.6 lbs of CO2 per gallon = 9,800 lbs/2,000 = 4.9 tons of CO2 per year. A before and after posting would look as follows.

CO2 per year before /Transport 8.258 tons / Propane 1.65 tons / Electricity 10 tons/ = 19.9 tons

CO2 per year after /Transport 3.22 tons/Propane .825 tons / Electricity 0.00 tons/ = 4.04 tons

19.9 tons/4.04 tons = .203 = 1.0 - .797 = .797 x 10 = a 79.7% reduction.

If we add in the 2,800 miles of 5th wheel trailer towing we will do this year plus 600 miles of driving around on vacation without the trailer we end up with the following.

2,600 miles /9.5 mpg = 273 gallons = 5,350.3 lbs /2,000 = 2.675 tons.

400 miles /19 mpg = 21 gallons = 412 lbs / 2,000 = .206 tons + 2.675 = 2.88 tons of CO2.

19.9 tons/4.04 tons + 2.88 tons = 19.9/6.92 tons + .825 tons = 19.9/ 7.744 =.389 =61.1%

As you can see towing a 5th wheel trailer really impacts our CO2 emissions increasing it from nearly an 80% reduction with all our efforts to nearly only a 60% reduction with the extra fuel consumption. The situation is not nearly as bad as it looks as a fair accounting would add the extra 2.88 tons to both sides of the equation. It should look like 22.78/7.744 = 66%. This is still significant, but not nearly as bad.

There are other measures for future considerations that are worth a look. In the first place our net exports of electricity really should be deducted from our total tonnage. After all we produce them but we do not use them so they should be considered Carbon Credits (the real kind, not the legerdemain of the purchased kind). Four hundred dollars ($400) a year at $.08 =5,000 kWh (or 5 tons a year) equals a year. This is going to be less this year due to PHEV charging.

This brings up an issue that does concern us for the future and that is a reduction in our buy back rate in the year 2021. Currently EPE pays us 8 cents a kWh for exported power but this was only locked in for eight years when our system was installed. Our plans are to use more of our power by then and sell less. We see no reason to subsidize the utility when they won’t pay us a fair market value for our power.

Our truck will be paid for by then and we could buy a full BEV with 200 mile plus range and just shift more of our driving over to electric power at that juncture.

Last month we bought a 240 volt charging unit for our car. This will do two things for us. First of all it will charge the car in 2.5 hours instead of 7 hours which means we will have a faster turnaround time which should increase our EV miles modestly. Secondly our charging efficiency is around 72% now so this should improve that equation (to about 82%) meaning we will average less watt hours per mile factoring in the power it takes to charge the battery in the first place. We have our garage already wired for 240 volts so we just need the unit to plug it in. So far the improved charging efficiency has improved our average MPG e from 55.7 MPG e to 61 MPG e.

A few years ago we replaced our propane fired water heater with a new 40 gallon unit so it may be several more years until we need to replace it again. When we do I am looking at an electric tank less water heater. I will need an electrician to wire a 240 volt power supply for it but it looks like it is very doable. One of the reasons we never went tank less is you need a 5 inch flue pipe for gas fired units and all we have now is a four inch flue. Electric units do not need a flue at all and our water heating could be switched over to sunshine if we did this.

Lastly every 7 to 10 years we have had to replace our well pump because of the hard water our well produces. I never gave it much thought until recently but since we have a 3,000 gallon water storage tank and a pressure booster set up there really is no need for a high output pump to feed the tank.

They make lower output solar powered well pumps that could just pump when the sun shines and you can think of the storage tank as a storage battery. This would take our well off our current electrical needs and power it independently of the grid. This would be a good thing. We just need to be ready to make the switch the next time the pump fails.

That is about all I have to report on now. Our quest to reduce our Carbon Emissions was real and we think we have achieved quite a lot. There is more to do and we will do more as time and resources allow. Not everyone will have the same story we have, nor will they have the same perceived needs.

Some folks will live closer to town then we do and a pure EV could meet more of their needs. Possibly an electric bicycle could meet more of your transportation needs. Some folks may have no interest in RVing which would reduce their Carbon footprint greatly. They may be interested in dietary choices like Vegetarianism which we are not interested in. Some of you may be able to garden more which can be a real emissions reducer. We have a raised bed and had to haul in all of our soil to even garden at all.

We all need to look to doing what we can to reduce our Carbon emissions within the structure of our own life styles and locality. Solar and wind power is a real paradigm changer in this personal equation. Without grid tie solar we could never have reduced our emission as dramatically as we have. The solar being used for transportation miles is a real paradigm shift also.

You really need to approach Carbon emissions with your eyes open. For every unit of energy you and your family use society at large use three to five units of energy just to support you. You need to be realistic about the reality of the society we all are embedded in. This mix of renewable power v fossil fuel power being used by society will improve over time with a shift to more renewables.

There is very little you can do to reduce the amount of energy (or carbon emissions) society is using (or emitting) on your behalf. Some of your choices may reduce this equation but end up making more energy available to others who could care less. You just need to know that all these personal choices you are making can and does inspire others to do likewise.

There has been way too much discussion about reducing carbon emissions and not enough people just doing what they can do on their own and not waiting on a government mandate to do what is right. We can talk about leaving fossil fuels in the ground all we want but until more of us stop going to the gas station, to the Gas Company, etc. and buying the addictive products it just isn’t going to happen.

We make it a practice to only go to the gas station using electric power only. We stuff 6 or 7 gallons in the car and leave the gas station without using any gasoline. We only need to visit the place once every 3 or 4 weeks. While this isn’t as good as not buying gasoline at all, it is way ahead of nothing. If we all collectively continue to use less in the way of fossil fuels this will keep the pressure on the purveyors the this planetary ecocidal product.

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