It’s important to understand the difference between these two interrelated energy terms as it has a big bearing on your pocket. This article is designed to be as simple to understand as possible.
Temperature is the physical state of something measured in degrees and kWhrs is a measurement of an amount of energy. Everyone should understand this, it’s not too difficult. To give you an example where this can be used, there are more than enough kWhrs of heat in the ground outside your home to heat it for its entire life a million times over. So why don’t we ?.
The problem is that this heat is at the wrong temperature. We need the temperature to be higher than the the item we are trying to heat for there to be a potential to extract it. It’s easier to understand if you think about water, for water to move from one place to another, the source must be higher if you want the water to travel freely OR if the water source is lower, you will need energy to pump it to the higher point. (This is basically what a heat pump is)
The following is a technical example (we will keep it simple) of how the harvesting of daylight completely undermines the use of legacy solar hot water panels which use the greenhouse effect. In this example we will just concern ourselves with the everyday heating of hot water in a 300L cylinder. It will become clear the significant financial difference temperature makes.
Watch this video first just to see how powerful HONE is so the information below becomes more relevant. the HONE heat engine temperature is at 76C and climbing.
Below we are going to look at the difference temperature makes to the financial return on renewable energy.
Conditions of comparison example: In this comparison we are going to heat a hot water cylinder of 300 Litres from cold. The incoming cold water is coming into the house at 10 degrees Celsius and we want to heat the cylinder to 60 degrees Celsius. We are going to assume a cloud cover of approx 300 to 400 watts/sqm of light coming through the cloud.
We are going to compare HONE (Case 2) and legacy type Solar Hot Water panels (Case 1).
House One….Legacy Solar Hot Water System…
A solar hot water system will have low or no performance in cloud as solar relies on the greenhouse effect which requires sunshine. A solar hot water system in this situation will add approx 15C at best or 18972 Kilojoules (5.27 kWh) of energy. This will take the water up to 25C, still cold to the touch as your skin temperature is approx 36C.
This free energy equates to 0.52 Litres of oil and using a standard oil boiler hot water only efficiency of 64.4% (BRE Hot Water Only) equates to a saving of 0.80 L/oil and 0.64 cents.
If you assumed this happened everyday just for the purpose of the lesson, the annual saving would be €233 in oil from the solar hot water system. (Note the solar panel system would need to be at least 7.3 sqm in size for this kWh rating, a single solar panel would only create savings of approx €47 per year (SEAI DEAP)
As the water is still too cold to shower with, we need to fire the boiler to finish the heating of the hot water to a temperature we can use, this will rise it by a further 35C to 60C as the boiler set point is 60C minimum due to Legionnaires disease legislation, i.e. the lowest setting a boiler stat can be set at is 60C.
The Oil Boiler in this situation will add additional 35C of hot water or 44280 Kilojoules (12.3 kWh) of energy. This will take the water up to 60C.
This boiler energy equates to 1.23 Litres of heating oil and using a standard oil boiler hot water only efficiency of 64.4% (BRE Hot Water Only) equates to a spend of 1.9 L/oil and a cost of €1.52 cents.
If you assumed this happened everyday just for the purpose of the lesson, the annual spend would be €554.80 in oil to heat hot water as per this example.
House Two….HONE System…
A HONE system will have excellent performance in cloud as it is solely a Daylight harvesting nanotechnology. A HONE system in this situation will have no problem adding the full 60C requirement or 63288 Kilojoules (17.58 kWh) of energy. This will take the water up to 60C. However it is typical the HONE system will continue to heat past this temperature.
This free energy equates to 1.75 Litres of oil and using a standard oil boiler hot water only efficiency of 64.4% (BRE Hot Water Only) equates to a saving of 2.7 L/oil and €2.16 cents.
If you assumed this happened everyday just for the purpose of the lesson, the annual saving would be €788 in oil from the HONE system. (Note the HONE system would be approx 8.8 sqm in size to achieve this)
In summary, now imagine these houses are beside each other and everything is the same, same size, same people who use the same amount of hot water daily, etc. Let’s see how they compare.
House one (Solar Panels) saved €233 but still spent €554 on oil. House two (HONE) spent nothing on oil but saved €788. The HONE household did not spend the €554 the solar house had to so it was better of by €554 and it also got free hot water with a value of €788.