Press Release: Patent Obtained – Technology for Issuing and Trading Granular Renewable Energy Certificates through Daytime EV Charging and V2G Supply-Demand Time-Shift

Denryoku Sharing (D-Sharing)

September 14, 2023

Denryoku Sharing Co., Ltd. (D-Sharing; based in Shinagawa-ku, Tokyo; Chairman & CEO Naoki Sakai) announces that it has obtained a patent (Japanese Patent #7246659) for basic methodology for quantitatively measuring, evaluating and trading values of carbon dioxide (CO₂) reductiongenerated through, for example, charging of electric vehicles (EVs) during daytime when Carbon Intensity (CI)[1] of electricity supplied from power grid is low (typically, sunny daytime); and balancing out demand and supply through charging to and discharging from EV batteries over V2G[2] and V2H[3] arrangements by using bidirectional inverter[4]. Measurement is carried out at a defined time interval, which can be used for issuance of so-called granular renewable energy certificates.[5]

EVs are generally regardedas cleaner vehicles, emitting less CO₂ compared with internalcombustion engine (ICE) vehicles[6] and, thus, would significantly contribute to decarbonization. However, CI of the electricity used for charging EVs matters. If the CI of the charging electricity is 0 (zero), you can literally claim that your EV is carbon-free.[7] On the other hand, if the CI of the charging electricity is high (e.g., in the evening when the power grid significantly needs to rely on fossil-fuel-fired thermal power plants), your EV may not be so clean. By using this patented technology, each EV’s comprehensive contribution to CO₂ reduction,including CO₂ emission related to electricity used for charging, canbe measured meticulously for the issuance of granular renewable energy certificates. Such certificates can then be traded, which in turn would incentivize 24/7 carbon-free electricity supply.

To cope with theintermittency of renewable-energy-origin electricity generation (due to sunny vs. cloudy/rainy, windy vs. windless, and day vs. night) and resulting supply-demand mismatch, electricity demand must be managed in a rational way. Since storing electricity, by means of pump-up hydro, battery, etc., almost always involves some 30% of loss, generated electricity should be used as it is generated, to the extent possible. Hence, we would like to recommend, again to the extent possible, charging EVs during daytime when renewable-energy-origin electricity from solar panels is abundant[8]. As is already indicated above, if there is no imminent need for long drive, electricity stored in EV batteries can then be discharged over V2G and V2H arrangements when grid’s (or home) electricity demand is high. By using this patented technology, values of CO₂ emission reduction through suchtime-shifting can also be measured meticulously for the issuance of granular renewable energy certificates. Proper incentives can, thus, be created for such demand management through time-shifting, for large-scale adoption as well as individual household adoption.

D-Sharing joined UnitedNations’ 24/7 Carbon-Free Energy Compact[9] and intends to collaborate with UN by using, amongst other technologies and initiatives, this patented technology.

[1] Electricity from power gridcan be “cleaner” or “dirtier” depending on how its generation sources are mixed. It is very clean when the generation sources are renewable-energy-origin only
(e.g., sunny daytime from solar) whereas it becomes dirtier when fossil-fuel-fired thermal power plants need to kick in for balancing out demand and supply (e.g., during peak demand time in the early evening). CarbonIntensity (CI) refers to how many grams of CO₂ are emitted toproduce a kilowatt hour (kWh) of electricity that is typically measured each and every hour for a power grid concerned. CI fluctuates widely for some power grids (e.g., those in Japan).

[2] V2G (vehicle to grid): By connecting parked EVs to power grid, theycan be used as “swarm electricity storage”. Electricity can be charged from the grid to the EV batteries or discharged from the EV batteries to the grid to help balance out demand and supply simultaneously.

[3] V2H (vehicle to home): Similar to V2G, by connecting parked EV tohome, which may have rooftop solar panels, it can be used as electricity storage. Electricity can be charged to the EV battery when home consumption is less than supply from solar panels, or discharged from the EV batteries to home when, for example, electricity tariff is high during peak-time or when power outage happens (e.g., due to natural disaster).

[4] Newer EV models are increasinglyequipped with bidirectional inverter.

[5] as opposed to “conventional”renewable energy certificates (RECs) which do not have so-called “time-stamps”

[6] While typical ICE vehicleemits about 160g of CO₂ per km driven, typical EV emits only 50-100gof CO₂ per km driven thanks to energy efficiency of electric motorcompared with ICE. (D-Sharing estimates)

[7] This argument, however, doesnot take into account the costs of production and disposal, a.k.a. life-cycle costs. Life-cycle CO₂ emission reduction benefit of an EV over atypical ICE vehicle can be realized only after driving some 90,000km.

[8] but, in certain circumstances,not even utilized and wasted

[9]  https://www.un.org/en/energy-compacts/page/compact-247-carbon-free-energy