Energy Efficiency

 It's interesting to see how big of an effect mindset can be on society. Here I will share a few of my thoughts on the subject of energy efficiencies and management.  I do believe very much in reducing or eliminating waste.  As an engineer, it is my job.  If we focus on waste elimination we will positively impact costs as well as reduce energy needs and pollution.  If we just rethink how we acquire and use energy, I believe there are substantial wastes that can be reduced or eliminated.

The views expressed below are just my personal thoughts on opportunities for more efficient use of energy and a pathway to a much cleaner environment.

Transportation

Personal commuting

Commuting is the task of moving people (and related cargo) from one place to another.  I see this is a bit different from driving but it certainly includes that. I will focus on energy here rather than get into autonomous commuting.  A typical petroleum powered vehicle is less that 40% efficient use of fuel energy for propelling the vehicle, and that is when it is actually moving.  At least 60% goes to waste, mostly in the form of heat.  Then when we want to decelerate (brake) we dump all that kinetic energy into even more waste heat. That is very significant energy waste.  Also consider how much time is spent idling at a stop.  Integrate this waste over a typical drive cycle and very little of the total energy consumed is used for propelling the car.  Extremely wasteful.  Hybrid powertrains can really help especially in city traffic.  However a hybrid still lugs around a very heavy inefficient powertrain that requires significant maintenance.  I believe that the best powertrain for nearly all commuters is pure electric.  Here are some of my reasons:

• Nearly zero maintenance.  No oil/filter changes, no coolant flush, no trans service, no spark plugs, no accessory belts, no idling, no hoses, no air of fuel filters, etc.  The electric powertrain is far simpler with less moving parts to maintain or fail. This significantly reduces waste of not only energy but also generation of trash, much of it being hazardous waste.
• Longer service life.  While engines and transmissions have improved in durability, they still pale in comparison to an electric powertrain.  There is of course the battery which is the biggest challenge for electric vehicle durability.  However, battery technology continues to improve and with the increased focus more recently, I believe we can solve this problem and have energy storage that lasts for decades soon. Until then, we can recycle batteries.  
• Regenerative braking.  Instead of just wasting the kinetic energy slowing the vehicle down with brakes, a well design electric car recovers most of it, storing it back in the batter to be used on the next acceleration.  This is a huge deal!  Not only does this drastically reduce brake wear and dust pollution, it saves energy.  You get to recover a portion of the kinetic energy and use it to accelerate back to speed. This is a clear win-win no brainier.  
• No idling, ever.  Electric vehicles do not use propulsion motors to power anything but moving the vehicle.  All accessories are electric so they can run independent from an engine.  No more wasteful idling ever.
• No need to waste a trip to "refuel".  Unlike petroleum, electricity is already available at our homes, businesses, hotels, stores, etc.  Because of this you don't have to make a special trip, or add a wasteful stop in your commute to refuel.  Instead, the vast majority of daily commuters can simply plug in at home, work, the store, restaurants, etc.  You don't need a special charging place but rather just charge at the places you already go.  No sitting and waiting to refuel.  The refueling happens wherever you stop. This is a big paradigm shift I don't feel many people really grasp.  When electric cars are discussed, people always go right to lack of charging stations as the reason they are not ready for an electric car.  Those should only be needed for long distance drives.  You should never need this for our daily commuting.  I think people get stuck in current mindsets and struggle to adapt to this new approach.  I believe we will get over this. If we all went to electric vehicles we would not need anywhere near the dedicated charging stations that we have gas stations in town.  We would only need them along interstate highways.  In town any building can have charging ports at parking spaces but even these would not get near the use that gas stations do today.  All hotels, restaurants, work places, grocery stores, etc., can have charging stations and some already do today. Inductive charging is coming too.  This will allow wireless charging like some cellular phones have today.  Just pull into a parking spot and charging will happen automatically. Since charging still takes significantly longer than filling a fuel tank, we will need more charging stations on interstate routes away from towns.
• Ability to heat and cool the vehicle while it is parked and even while sitting in the garage.  Instead of hoping into a cold or hot car, or having to start and warm up the car (more waste) you can run the heated seats and HVAC before you even get in the car.  You can even do it (for short periods) while it is in the garage with the doors closed.  This actually helps maintain your range as well since you can do this while it is plugged in and not use the battery.  Another benefit is safety since you can warm the windows and prevent fogging before you drive away.
• I believe we will soon have more modular battery solutions.  While permanent in-car batteries will likely continue, we will augment that with portable batteries that can be used not only for extending your car range but also standby power for your house and portable power for camping and other things.  We can think more wholistically about batteries and all our electric needs and buy modular batteries that have multiple uses.  We already see this in power tools today where you can use the same battery in a drill, weed whacker, leaf blower, etc.  When it comes to larger batteries for cars and homes, this concept can scale up.  If we can standardize in this space, we can even have a battery ecosystem that would allow for swapping depleted batteries for charges ones quickly.  While you are charging your cars main battery at the roadside station you can also swap out a few battery modules, reducing your stop time and extending your range considerably.

Mass Transit

City bussed and local trains can and all go electric.  The same comments for cars apply here.  The use cycle is of course much larger as busses operate all day long.  They do spend a significant amount of time idling at stops.  They also make short acceleration/deceleration cycles constantly.  Here the savings switching to electric is big.  Not to mention the emissions from petroleum powered vehicles in some of the more confined inner cities, tunnels, and drop-off zones in large venues can be a problem. Then there is the noise reduction as well.

Delivery, garbage, mail, etc.

All of these vehicles have even more start-stop and idling periods than the mass transit category above.  Same concepts apply but with even bigger energy savings.

Where does battery electric maybe not make sense?  

I believe there are several categories where hybrid powertrains are likely the best instead of pure battery electric:

• Sports cars.  While you can make very high-performing electric sports cars, many drivers would miss having the engine as part of this experience.  The Porsche 918, Ferrari LaFerrari, and McLaren P1 were some earlier examples showcasing what hybrid powertrains can do for performance.  These applications do not need much energy storage since the car depends mostly on the engine to supply most the power, only using hybrid to enhance performance and braking.  This approach should make it's way across most sports cars, not just these supercars.  It can be enhanced to provide better active torque vectoring and traction control too. This is a small market share and collectively does not add up to much energy waste in the big picture.
• Long-haul trucks, especially going over mountain passes.  Hybrid makes the most sense here to give the truck a long range and keep the weight reasonable.  The hybrid power can be used to downsize the engine to optimize it for Brake Specific Fuel Consumption (BSFC) while at steady speeds under typical loads.  Use hybrid power to add acceleration and hill climbing power and for regenerative braking.  It could even be possible to make smart mountain passes where trucks going up can take power harvested from trucks going down.  This would improve safety by keeping the brakes cooler as well.  

What about the waste and environmental impact of all those batteries?

Many electric car opponents discuss the cost, energy use, and waste of the batteries for electric vehicles.  It is certainly true that there is a real cost and we need to manage how we handle batteries at the end-of-life.  Todays batteries are hazardous waste.  However, these batteries are getting better and lasting much longer than they once did.  We can also develop recycling programs to recover the materials from the expired batteries.  Of course that is not cheap either.  Energy storage is an engineering problem to solve and as demand increases, the motivation to solve this will also increase research and development. With a world of smart people working on this, I believe we will see breakthrough invention and innovation make step-change improvements as well as continuous improvements in this area.  New electric energy storage can be relatively easily retrofitted to existing electric cars too.  I believe if you buy an electric car now, by the time you need to replace your battery there will be cheaper and better options available than there are today.  These better options can also increase the range of the vehicle, and potentially the charging rate.

Carbon Neutral Fuel

During the energy transition, we should also develop and implement synthetic gasoline.  Many are working on this including Porsche.  Today there are businesses operating to capture CO2 from the air only to pump it underground and earn carbon credits.  Instead of doing that, we can capture carbon from sources like exhaust stacks or both stationary and mobile sources where high CO2 concentrations exist and use that to make synthetic gasoline.  The big benefit here is that it can be used in the cars we drive right now.  The average age of cars on the road today is over 11 years old.  If we completely stopped building internal combustion engine (ICE) cars today, even 11 years later we would have a large population of them still on the road.  Carbon neutral synthetic gasoline can have a huge immediate impact.  Porsche and Siemens are working on this fuel and producing it right now. More on the Haru Oni plant here.  In very remote areas, the CO2 can of course be captured from the air too to make this fuel. One of the big carbon emitters today is aircraft and a synthetic fuel can certainly hold promise for reducing this substantially. 

Electric Power

Our traditional mindset has a grid with large centralized power generation facilities generating the electricity and distributing it with weather prone ugly powerlines.  It seems most still look at this mindset when applying solar power.  Why?  Instead of making large solar power projects that cover acres of land and then having to send it over these powerlines, why not generate it at the point of use, or at least much closer to the point of use?  Every roof can be used to generate solar power.  Picture every large building having an optimized solar grid on the roof.  Not enough space?  OK, cover the parking lots too. Everyone would get nice shady parking and no land is wasted.  Parking lots are not exactly a view anyone will miss and keeping the sun off the cars will is another big benefit.  Empire Cat has done many solar parking lots in Arizona. This seems so logical to me. One of their installations at Sky Harbor Airport can generate over 4GW.

Homes are starting to get more solar power and this makes sense, especially in places like the desert where sun is abundant and air conditioning is one of the highest power consumers that happens to coincide with the most solar power generation.  This can also be used to charge the electric car in your garage.  

Home energy storage has many benefits and should expand going forward.  As small-scale local energy storage (mostly batteries) becomes more affordable and longer life, this will really help stabilize the grid and ensure more homes don't loose power during events with the grid (power outages).  It would be great to see less high-tension power lines in the world.  They are expensive, weather prone, and ugly and nobody will miss them,  

I see a continuing need for the power grid but only to fill in the gaps where/when solar cannot be generated, and to move power around from producers and consumers.  Every building can be both a producer and a consumer.  

I think there are places for wind power generation.  Like solar, you are dependent on mother nature to provide the right conditions.  In both cases, alternative power and energy storage will be needed at times.  I believe natural gas cogen plants can fill this need well in cases where the power is needed for longer periods.  Nuclear power can also be used here.

Electric energy storage can also be used to make better use of solar and wind energy.  Energy storage does not always mean batteries.  There are many methods of storing and retrieving energy.  

Hydroelectric power is one of the best power sources and we should of course continue to maintain and utilize our dams.  

I still believe there is a place for coal and natural gas power, primarily as standby or peaking power, especially during the energy transition.  This can be started for cases like the Texas deep freeze of 2021.  Keep this electric generation capacity available but use it as a last resort.  

Thermal Energy

We heat and cool our homes and other buildings.  We also convert energy to heat for things like hot water, drying our clothes, etc., and move heat for air conditioning  There are many inefficiencies here where we can make better use of the thermal energy and reduce the need of gas, coal, oil, and electricity.  Take for instance a typical home on a hot summer day.  We run the air conditioning to pump heat to the outside while we use other energy such as gas or electricity to heat the water and dry our clothes in a dryer.  Why do we take the air conditioned air from inside our home only to heat it to dry the clothes?  Why can't the dryer take the heat you are already pumping out of the house to heat the clothes in the dryer?  In fact, why can't it take the hot air from outside to start with already hotter air on warm days?  These things can easily be done actually.  To start with we need dryers that have both intake and exhaust pipes instead of just exhaust.  Then we can bring pre-conditioned air into it and optimize this energy.  

Today you can buy heat pump hot water heaters and these really make sense in certain hot climates.  Geothermal systems also make sense and can be used to also heat the hot water.  In the summer heating your hot water will actually save energy versus just cooling the house.  Hot water heat can and should be added to heat pump systems in hot climates.  You take the heat from where you don't want it (the house) and pump it to where you do (the hot water tank).

There are times when you can simply bring in outside air to heat or cool the home.  If you have a smart thermostat and air handling system, you can monitor the temperature and humidity inside and outside.  If conditions outside become more desirable, just pump that air into the building.  This also brings fresher healthier air into the house.  In some cases you may want to add better filtration systems to the air coming in from outside but that is cheap and easy.  Active duct valves are also needed to make each room in the building comfortable.  This becomes especially important in multi-story buildings.  In buildings with a basement, you may be able to cool the top floor simply by bringing colder air from the basement and pumping it to the top floor.  This will make both spaces more comfortable.

In the winter we take warm air from inside our homes, heat it more in the clothes dryer, and then pump it all outside while our heating system runs trying to heat the house.  Often people will also run a humidifier to add humidity to the house.  Instead, you can simply use the hot humid air your just produced in the dryer.  You would still want to condense some of that humidity out and you may want to employ a heat exchanger for most the air as you can add too much humidity but the current state is very wasteful.    

Thanks goodness we are finally replacing wasteful incandescent and halogen light with LED.  This really makes sense in hot seasons and climates.  Back in the day we would run incandescent bulbs which used over 80% of the energy they consumed to produce heat, only to have to run the air conditioning more to pump all that waste heat back outside.  That is very wasteful.  

Owning a Geothermal HVAC system

I bought a house in 2012 that had a Water Furnace geothermal system in it.  The system has a geothermal domestic hot water (DHW) heating system integrated in it.  The system was installed when the house was built in 2004.  It uses vertical wells in a closed loop.  A water mixture circulated through the wells in a loop that goes to a heat exchanger in the geothermal HVAC system mounted in the basement.  There is a heat pump that uses this ground loop to transfer heat either to or from the house for heating and cooling respectively.  Heat is also added to the hot water tank when the compressor is running.  The hot water tank is just an electric hot water heat that is not connected to power.  The geothermal system pre-heats this water tank before the water enters the main hot water heater so the main hot water heater has much less heating to do.  Here is a graphic explanation showing the cooling mode:

Here it is in heating mode:

Like all heat pumps, they move heat rather than generating it (for the most part).  The actual heat comes from the ground.  The compressor does have some inefficiency so it does generate some heat as well.  Heat pumps have a coefficient of performance rating which indicates how much energy they move versus how much energy is required to generate the total heat.  In other words, you may spend $1 to get $3 worth of heat.

There are many benefits to a geothermal system.  Of course the energy savings is one.  However, there are many others.  There is no noisy ugly outside HVAC condenser for one.  There never seems to be a good spot for the outside condenser unit in a typical air conditioner.  They also collect leaves and the fans can fail.  The geothermal system has no outside unit so your yard looks nice and you don't have that noisy thing to deal with.

The geothermal system has a large cooling capacity for summer.  Since it is sized for heating, the cooling capacity in many climates is more than is generally needed so it has no trouble at all keeping the house nice and cool all summer. Also, the ground temperature it is exchanging heat to is much cooler than the outside air in the summer so the compressor has much less work to do.

Like all heat pumps, the heat comes at a lower temperature.  Most furnaces put out very hot air for a while then shut OFF.  They wait until the temperature in the house drops then they do it again.  This leads to cycling between too hot and too cold.  The heat pump (geothermal or air exchanger type) run the fan much longer but put out warm but not hot air.  This leads to a more comfortable room temperature and better circulation in the house.

The geothermal system is better than a typical heat pump since it uses ground temperature instead of trying to move heat to and from outside air.  I have owned homes with the traditional heat pump systems.  They work just like a regular air conditioner in the summer.  In the winter though, they have issues.  The outside coils, acting as an evaporator in the winter, condense moisture on them and freeze up.   To defrost the coils the heat pump must reverse and heat the outside coils back up.  This is an energy waste and interrupts heating of the house.  Also, the heat pump is always trying to push heat the hard way as the air temperature become less desirable for this.  For instance, in the summer it has to push heat outside.  As the outside temperature increases it takes more energy to achieve this.  In the winter it is trying to extract heat from outside and as the temperature drops this takes more energy to achieve.  At some temperature, it can't really heat the house anymore and backup heat is used.  This backup heat is usually an electric grid (translation: very expensive to run).  In contrast the geothermal system is always exchanging heat with the ground temperature which is much more stable. Traditional heat pumps work well in very dry climates where the coil freezing issue is much less.

So, how much savings is there.  Below is a chart showing the energy use for my house compared with typical houses in my area.  I got the data from Ameren which provides both electricity and gas for our area.  I converted the gas therms into kWh units for this comparison.

As you can see the energy savings is quite significant.  This is total energy for the house, gas and electric.  However, depending on costs of each, the dollar savings can be much less.  Here is the costs for this same period, again comparing with typical homes similar to mine in the same area.

Right now the costs savings is not that big because electricity costs are high and natural gas costs are very low in this area.  This value proposition changes with varying costs of each.  Back when the house was built in 2004 natural gas was very expensive compared to now.  For those interested in reducing carbon foot print though, the geothermal system always wins.

This comparison is for total energy used in the home and includes all energy use.  We have converted nearly all our lighting to either CFL or LED.  I run a weather station off my main PC so it is always ON and awake.  We have gas for the fireplace and oven/stove only.  Everything else in the house is electric.  Our house was built in 2004 to the standards then and is fairly typical construction. We heat and cool the whole house all the time including the basement.  We keep it about 71F in the winter and 74F in the summer.  This comparison is not between identical homes or use of those homes so there is quite a large margin of error, in the plus or minus 20% range I suspect.

As I mentioned before, my system has geothermal water heating.  There are some drawbacks to this.  In the spring and fall when the system is not needing to heat or cool the house, it also stops producing hot water too since the compressor does not need to run.  Hot water is only produced when the compressor is running.  This just means the main hot water heater has to produce all the hot water so your cost savings goes away.  In the summer the system is very efficient because it dumps heat from the house into the hot water.  You get a double benefit.  Even in the winter though, my geothermal hot water hits over 110F so my hot water heater barely runs at all.  Given the low natural gas prices now in into the near future, I plan to replace my electric hot water heater with a natural gas unit to further reduce my costs.  I can also install some floor heating using the hot water.  In addition, I would like to remove the electric emergency heating grid and replace it with a radiator using hot water.  Right now my system will occasionally use the emergency heat when the temperatures get below single digits (F) which seems to happen all too often here.  I have a high efficiency natural gas fireplace I use during cold ambients to prevent using the emergency heat now.

There are many other types of geothermal systems.  Mine is closed loop as I mentioned.  Open loop systems pump water through them.  For instance, you pump water out of a well, through the heat exchangers in the geothermal system, and then it flows into another well back to the ground.  You can also use a lake or river for the water source.  Each of these systems makes different trade-offs.  The optimum system varies by your area, local laws, ground water levels, drilling costs, climate, and more.

Make sure your installer does the job correctly!  Our house had an issue with galvanic corrosion of copper and brass parts because they did not put dielectric fittings on all connections with the hot water tank.  This actually caused blue coloring on the bath tubs and other fixtures.   It also ate the water tank and several heating elements. Water heaters must have dielectric fitting on all water connections!  This is required because if the different metals used in the house plumbing and water tank.

Damage from galvanic corrosion. This fitting needs a dielectric connector to isolate the water heater from the rest of the plumbing.

Geothermal tank is closest to HVAC system (right).  Valve that is missing the dielectric fitting is at the bottom.

I fixed this when I replaced the water heater.

New tank and fittings with dielectric fitting in place

Another thing people often mess up is the use of the geothermal water tank.  Its important that this tank have a water loop the the geothermal system.  I have heard about system where the installer just put the geothermal inline with the tank intake.  This does not work!  When the geothermal kicks ON, it must circulate water through the tank.  Also, do not heat the geothermal tank (do not power it).  The idea is that you are pre-heating the water before the main water heater.  If you heat it (by connecting the heater to power) you will not get much if any geothermal heating.  The heater will heat the tank up and the geothermal will just turn OFF the water heating function.  Some people do connect the heater to power for use in the spring and fall when the geothermal is not producing much heat.  You can do this if you need more hot water but remember to turn it back OFF in the winter and summer.

Make sure the water lines from the water tank to the geothermal system are well insulated.  If you don't you will get fairly significant heat loss to the room.

Enhancements

Thermostat

I recently installed a modern thermostat on this system.  I used the Honeywell RTH9580WF.  This is a programmable thermostat that supports 2-stage heating and cooling and emergency heat.  One thing you need to consider when setting this up is the heating schedule.  Make you it does not vary much.  I plan to let it drop 2 degrees at night (because it like it cooler at night).  In order to warm it back up in the morning though, you need to bring the temperature back slowly.  No more than about 1 degree per hour.  Attempting a faster rate may engage the emergency heat.   You can create any cooling schedule you want since the system can easily handle even rapid cooling changes and has no emergency cooling mode.

I tried to find a thermostat where I could better control emergency heat but have been unsuccessful.  I have also considered putting an X10 module in-line with the emergency heat wire to block it unless the outdoor temperature is below a threshold, or the inside temperature has dropped below a threshold.  I can do this with data from my weather station system.  I created a .Net plugin that reads the weather station data and can control X10 devices.  I would need to add to that project for this functionality but it would be pretty easy.

Emergency Heat

I would like to replace my emergency heat system.  Today it is just an electric grid.  I would like to start by replacing my main hot water heater with a high efficiency natural gas unit.  It could be either a tank type or tankless.  Then install a simple radiator in the air handler, downstream of the main coils.  Basically, just remove the electric grid and replace it with a radiator (water to air heat exchanger).    Next, connect this radiator to the outlet of the hot water heater with a circulation pump, returning the water to the intake of the geothermal tank.  When emergency heat is needed this pump would turn ON circulating the water through the radiator heating the house.  This water is heated with a combination of geothermal and natural gas which is far cheaper than the electric grid.  A similar loop can be used for radiant floor heat.

With natural gas prices low, and expected to be low for a long time, this could pay off reasonably fast.  It also depends on how big your ground loop is, and how harsh the winters are.  If your ground loop is to the small side, and you have harsh winters, this could really make sense.  It may also make sense if you really want more temperature variation in the winter.  For instance, you like to sleep at 65F but you want 71F in the morning.  

Direct Ground Loop Cooling

Another enhancement I have considered is using the ground loop water directly to cool the air in moderate seasons.  The ground loop water is about 55F .  In the spring and fall when the cooling load is low, the house can likely be cooled without even running the compressor.  Ideally a thermostat with 3 cooling stages would be needed.  The first stage would just run a circulation pump which pumps ground loop water through a radiator in the air handler.  The other 2 stages would be just as they are now.  As the cooling load increases, and the compressor is needed, it will heat the ground loop diminishing the value of this ground loop cooling mode.  It would work well in the spring, especially on days where it is cool at night (possibly even needing some heat) but it gets a bit hot in the house in the afternoon.  When the geothermal runs in heating mode, it cools the ground loop.  

The payback time for this could be long.  It would save cooling costs in the spring and late fall but the savings may not be worth the costs.