Accumulating small energy savings is having a large total effect on carbon reduction

The importance of reducing greenhouse gas emissions – typically carbon-containing gases, most notably CO2 – to prevent excessive global temperature rise is well understood. Our major energy sources, for generations now, have been fossil-based and therefore laden with carbon-based compounds that combine with oxygen when burned to create those dangerous greenhouse gases. They also emit other toxins as well as particulates that are damaging to health.

For some time now, we have been pursuing the goal to transition our energy sources from these traditional fuels to renewable sources. Springing to mind are perhaps the prominent of these, wind and solar energy with 3.37 terawatts of installed capacity now in operation worldwide, according to Statista *. Other sources include geothermal energy harboured within the earth’s core and wave energy induced by the gravitational effect of the moon.

Taking advantage of these sources is all about energy harvesting: converting that ambient energy into a form that is usable for human purposes. This is usually electricity and is predominantly produced by the large renewable-energy farms, both wind and solar, being installed in large numbers and across large areas of the earth’s surface.

These energy sources are quite satisfactory in many ways: today’s power electronics and conversion technologies can turn those few electron volts from PV panels, or the irregular, harmonic-laden waveforms from a wind turbine into usable electrical power. This may be a DC supply at a suitable voltage for powering loads directly, or for charging battery storage. Or it may be a high-quality AC output at a suitable voltage and frequency to feed in to the grid.

Making Less Go Further
One aspect that is less favourable, however, is scarcity. While there may be an abundance of sun and wind, and perpetuity is not in doubt, the quantity of electrical energy produced is quite low in relation to global demand, and generation is only possible when enough sun or wind is present. These times are not predictable or regular.

There are several practicable responses to this problem. One is storage: to make as much electricity as possible while the sun shines (or the wind blows) and store this in a battery array to be used later when ambient energy sources are not present. This is as valid in small domestic micro-generator applications as in utility-scale applications that integrate large grid-connected battery arrays. Some suggest these could be built from electric-vehicle batteries that still have about 80% of their capacity but are deemed to be unsatisfactory to continue their life on the road. Grid-connected storage is a hot topic with great potential, although best practices are yet to be finalized and much work remains to be done to install and connect enough storage.

The other side of the coin lies in reducing overall energy demand to meet the increasing installed capacity for renewables. There are several ways to do this, including developing more efficient appliances, improving power-conversion efficiency, and adopting more efficient processing techniques such as moving AI inference to edge devices and IoT sensors. We could also consider authoritarian measures such as enforcing limits on personal EV-mileage quotas through measures such as battery-charging caps or geofencing.

Smart Buildings
It is well known that a large proportion of the world’s energy is consumed in buildings, to power lighting systems, room heating, and water heating. Historically, these have been powered through a combination of electricity, as well as directly burning natural gas and mineral oil. In the push for net zero, energy for heating is expected to transition away from gas and oil towards electricity. This will have the effect of increasing the electricity demand imposed by buildings.

Reducing the energy needed to operate buildings, for the health and comfort of occupants, is one of many imperatives in the world’s pursuit of sustainability. Low-energy LED lighting reduces power demand by about an order of magnitude compared to traditional incandescent lamps. In the EU, legislation against inefficient lighting technologies included a ban on high-wattage incandescent lamps in 2009, followed by subsequent bans on lower wattages, that have encouraged widespread adoption of LED lamps in residential and commercial/industrial applications.

Also ongoing is the move towards smarter buildings that are capable of autonomously managing heating and lighting for optimum comfort and energy efficiency. A great deal of progress can still be made here, although the presence of large quantities of legacy electrical infrastructure including wiring and control systems such as thermostats tends to slow the pace.

Wireless technologies can offer a solution, allowing new controls to be installed with no new wires or significant decommissioning of old wiring. Bringing wireless technology together with energy harvesting to create self-powered controllers for lighting and HVAC (heating, ventilation and air conditioning) systems is facilitating the introduction of autonomous controls in smart buildings. No new wires are needed to provide power for the internal circuitry of the smart controllers, or to connect the controllers to smart lights or HVAC systems. And introducing these controllers has zero impact on the building’s overall energy demand since they are self-powered by ambient energy, using Peltier-type thermoelectric sources, solar cells, or kinetic energy conversion.

EnOcean has led the development of energy-harvesting smart controllers and now has a large installed base throughout commercial, industrial and residential buildings in Europe and worldwide. Individually, each of these units saves microwatts by powering internal circuitry from harvested energy. The energy saved by enabling smarter, autonomous control that eliminates reliance on occupants turning off lights when not needed, or turning heating settings down to reasonable levels is more significant. Autonomous lighting control, managed according to ambient light levels sensed using photoelectric detectors, permits additional valuable savings by adjusting the electrical lighting power to work with the ambient daylight, thus ensuring lighting is continually optimised throughout the day. Smart controls are reckoned to save about 20% of HVAC energy and 8% of electricity consumed by buildings.

CO2 Impact of EnOcean
Now having a large installed base of EnOcean technology, the CO2 impact can be assessed, and it is significant. EnOcean has developed a calculator, leveraging commonly used references, to quantify the savings in energy and, from this, the savings in generated CO2 achieved through EnOcean units controlling HVAC and small electrical power in buildings. More than 1 million buildings are now installed worldwide with EnOcean technology, in smart homes and commercial buildings. Overall, EnOcean is managing about 221 million square metres of smart-building floorspace. Based on official references for the energy demands of HVAC and small electrical power systems, these devices are currently saving 15% energy on average and by that more than 1.4 million tons of CO2 from the atmosphere, every year! And as more sensors are continuously installed, the annual savings will continue to increase.

Alone, of course, this is not enough to fulfil our urgent need to limit emissions and prevent damaging global temperature rise. But Smart Heating and Smart Power Control are comparatively inexpensive measures with a significant contribution that should encourage us all to increase our efforts to keep making progress.

*  Global renewable power capacity 2022 | Statista