June 25, 2018
Blockchain for EVs
With most talk about blockchain in transportation focused on freight and logistics, I want to explore the potential applications of blockchain for electric vehicles (EVs). To fully understand the implications of blockchain for EVs, let’s look at a brief overview of the blockchain, an engineer’s view if you will, characterizing the blockchain from its application advantages rather than the scientific underpinnings that one often finds perplexing.
Application-oriented Overview of Blockchain
The blockchain is a type of database technology, i.e., it is just another way of recording data. In this way, it is nothing revolutionary. What is revolutionary about it is the simple and ingenious way that blockchain ensures that the underlying data stays true over time. A database is as good as its immutability, or “unchangeability” or as I refer to it, its true-ness. Through the use of replication and peer-to-peer networking, a blockchain maintains copies of the underlying data or a ledger that is more robust than if just one party maintained it. This encryption and replication leads to increased trust in the underlying information making transactions easier and enforceable. While the technology as a whole is in its nascent stage, the elements it comprises of have been around for a long time, namely: peer-to-peer transactions — that have had applications in networking like torrents; and cryptography –- which is used to encode any sensitive information before it is transmitted on the network. Based on these characteristics, one of the first applications of the blockchain has been currency, where an anonymous and permissionless architecture is used, i.e., anyone can transact with anyone else without necessarily identifying themselves. An opposite application is smart contracts, which are essentially identity-based, permissioned environments. An identity-based, permissioned environment means everyone on the system is known, i.e., their identity is established, and they are “allowed” to transact, i.e., they are “given” permissions to transact. This architecture is similar to a company-wide intranet, where all the computers in the network are known, and only these systems have permission to use the network. One of the areas where smart contracts are most used currently is insurance, where the immutable nature of the blockchain makes the enforcement of the contract reliable and automatic. (Of-course tracking physical real-world truths and events in a digital transaction requires an oracle which is fraught with its own issues)
Applications of Blockchain for EVs
- Condition-monitoring: As cars start to be more and more instrumented, we have more ways of knowing the history of the car. The exact knowledge of history is even more important with an EV because the battery, which is the costliest component of the car, is highly sensitive to abuse. To understand this, we will take a slight detour into the science of lithium-ion batteries. Lithium-ion batteries (LiB) are electrochemical systems that store electricity utilizing the high electropositive character of lithium. While there are still many issues with LiBs, research is underway to try to make energy denser batteries, Cobalt based LiBs are some of the most energy dense batteries commercially used with energy density of around 150-200 Whr/kg. It is the high energy density that makes these batteries ideal candidates for portable energy storage applications like cell-phones and electric vehicles. However, if these batteries are not carefully operated, they can lead to thermal runaway and sometimes to catastrophic fires and explosions. Less dramatically and more frequently the batteries do not give desired performance. This performance loss can be observed in the form of loss of overall life of battery or loss of power/energy available during each cycle. System designers often over-design the system to account for these uncertainties. Factors affecting battery performance include operating conditions such as the charge/discharge rate, ambient temperature, etc. Based on the operating conditions, the performance of the battery can vary widely. While the EV manufacturer will take care — during the system design — to make sure that the battery stays within the limits to achieve optimal performance, accidental or intentional misuse can lead to the batteries being exposed to non-optimal operating conditions. Based on the extent and nature of these non-optimal conditions, the exact damage in the performance can vary. So, an immutable record of the condition that the battery has faced is crucial in estimating the current health of the battery. This immutable record then becomes the basis of contract between the battery supplier and the battery user.
Blockchain can help maintain the immutable record, at a slightly higher cost of replication, cryptography and networking. The contract could then help the user if the battery under-performs, replacing the current fixed-time warranty schemes that are prevalent today. Combining the trustable historical record with a physics-based model of the battery can result in accurate state estimation and performance prediction, which can help insurers confidently price premiums instead of considering conservative multipliers to take care of uncertainty. Leasing, the preferred method of EV ownership will also get a boost, as dealers will be able to price the vehicles appropriately based on actual usage and operating conditions.
- Secondary Use of Batteries: As EVs become more widespread and ubiquitous and as they start to pile up miles, we will soon have a lot of used batteries on our hands. Agencies like King County Metro already face severe challenges in getting rid of used batteries from the fleet of their hybrid EV buses. Batteries from EVs have to be discarded or replaced when they reach 80% of their original capacity. Some technology experts like JB Straubel profess that batteries that have reached 80% of their useful life are useless as they are too unpredictable and probably don’t have enough life left to warrant re-packaging. Although non-linear degradation has been experimentally observed for most batteries beyond 80% of capacity, many experts including ARPA-E (DOE) believe that secondary use of batteries is a potential market opportunity and therefore can help in the overall techno-economics of an EV. An immutable accurate record of battery history will go a long way in establishing confidence in the minds of users of these secondary batteries for applications like stationary storage etc.
- Energy Trading: This advantage of immutable record of accurate condition afforded by the combination of blockchain and physics-based model also lends itself to advanced uses of EV batteries like distributed energy resources in grid. With the use of some additional hardware to allow for efficient bi-directional flow of energy, a car battery can be used like any other energy storage system in the grid, with the added advantage of portability. The bi-directional flow of energy, often called Vehicle-to-Grid (or V2G) would allow EV owners, if they so choose, to participate in trading in energy markets, charging their batteries when energy is available for cheap, and discharging if the grid rewards them for their surplus energy. Further, this kind of trading and sharing of control can allow the grid to perform demand management in times of high demand. So they can delay the charging of some EVs when demand is high, thereby smoothing the load. While blockchain isn’t necessary for V2G and energy trading, it adds an extra layer of trust in the system, as each transaction is reliable and verifiable. Standards are in development to enable V2G and pilots are also being run to test the feasibility and gauge public perception around V2G and grid-level charge management of EVs.
- Democratizing Charging: One of the key issues faced by EV owners is finding a charger. While cities are working to provide public charging infrastructure of fast DC and level-2 AC chargers, these are few and far between and often unreliable leading to range anxiety among EV owners. Workplaces are also installing chargers with support from governments etc. However, the location and necessity of a charging event are hard to predict. Further, with the myriad of charge providers, it is cumbersome for EV owners to maintain a subscription to various charge providers leading to card overload. A solution to this is democratic charging, where we can allow anyone with available power the ability to sell this power to a car in need. One way to facilitate the transaction is to make the EV owners can carry devices that are calibrated and certified to report the amount of charge received. This is the solution that Ubitricity has come up with, where they provide users with a fancy cable that contains an energy meter that accurately measures the amount of energy received and communication capabilities that can send this measured total energy received value to the grid/energy provider for billing. In response to this solution, several city municipalities are considering installing power plugs on the light poles in the city (and due to the advent of LED lights lot of the existing light poles have now some excess power that they can share with EV owners). Along similar lines, echargie tries to be an Airbnb for EV charging, where they provide the ability to convert any existing plug into an EV charging port that EV owners can now plug into as if it were a public charging station, and billing is maintained through a mobile app. The democratic charging vision makes this extra “trust hardware” layer redundant. If the record of the energy/power transacted during charging is immutable (and recorded in a standard, agreed upon and commonly accessible way), then the EV owner can be billed for the energy usage anywhere, anytime. The vision of democratic charging is analogous to the way our cell-phone consumes mobile data. We seamlessly switch between towers and service providers, and all the settlement of finances, etc. are handled in the backend invisible to the user. A similar experience while charging an electric vehicle could make range anxiety a thing of past, and alleviate issues like remembering the appropriate method of using and paying for a charge.
An immutable record of the condition that the battery has faced is crucial in estimating the current health of the battery
When, where and how much of blockchain use is energy-efficient is a posed question, however automotive and transportation sectors are beginning to take note of the new technology and are gearing itself to move ahead full steam (or rather full charge) to bring in the era of blockchain for electric vehicles.