The conversation of electric vehicles mass adoption usually centers around two key issues: ‘range anxiety’, i.e. how many miles can an EV run without recharging, and the availability of public, private, and workplace charging infrastructure. While Tesla introduced the 300 mile battery, most auto manufacturers of plug-in electric vehicle’s (PEV) offer a battery range of up to 100 miles. However, with advances in research and the use of new materials in innovative battery technologies, range anxiety could soon become a thing of the past.
But there are other difficulties in PEV mass adoption, such as utilities policy, the need for standards, and addressing the various levels of charging that are available today. In addition, drivers are accustomed to fueling their gasoline-operated cars whenever they want and when they need it, where a well developed and established networks of gasoline stations enables such convenience. Can we build a similar network for charging electric vehicle batteries? Add to that the challenges utilities face with planning and maintaining grid capacity, energy distribution, reliability, and responsiveness to peak-demand events. Eventually, EV mass adoption would have a major impact on the electricity grid distribution, capacity management, and the costs associated with necessary system upgrades.
Adam Langton, Energy Regulatory Analyst at the California Public Utilities Commission (CPUC) presented at the Energy Storage North America conference in San Jose, CA last week and talked about the commissions policy decisions in 2013 and the challenges the utility industry faces.
Most PEVs require 20 kW for fully charging the car’s battery. Fast (sometimes called Super) chargers present an additional problem due to their kW utilization (60kW). Coupled with the possibility of clustering, where several EV owners in a small proximity, in one neighborhood, may all install fast chargers.
Today’s EVs are the ‘early’ technology and require different levels of capacity, depending on the charger type:
- Level 1 at 2 kW - with input voltage of 120
- Level 2 at 20 kW - input voltage of 240
- Level 3 Fast/Super charger at 60kW - with input voltage of 480 (like in Tesla chargers)
In urban dwellings, the National ratio of homes to transformers are 5 to 1, and a utility tolerance of 3 - 5 kW of coincident load. To increase the draw from the grid, utilities require the customer to pay for the upgrade. Further more, multi dwelling housing has a greater demand than single family homes in a defined geographical area, as there are many residents per square foot. If many of them are (or will be) EV owners, simultaneous charging will shift the loads and distribution requirements. To balance loads, energy storage capabilities are needed in urban settings. Operatively, large scale batteries are used to store off peak energy generation (such in solar generation during the day) to minimize the impact of vehicle charging in the morning and afternoon. Similar approach can be in storing energy at low rates (at night time) to be used at peak demand during the day. However, battery solutions are costly.
The California Public Utilities Commission (CPUC) made the following decisions in 2013:
Data gathered in 2012 wouldn't reflect the current landscape, since EV adoption is increasing every month.
- Need more time to understand EV impact on distribution costs
- Continue common facility treatment till 2016
- Limit common treatment to less than 7kW - NOTE: this limit has been removed, regardless of the type of PEV charger used.
- Need future method to reasonably assign costs
- Revise load research requirements.
In exploring various options, possible cost assignment strategies include:
- Having separate allowances
- Requiring a service connection upgrade flat fee
- Socializing the cost of capacity upgrade where small clusters of neighbors share the upgrade cost
- Limiting capacity for charging purposes of PEVs in residential clusters
- A combination of these strategies
In the process of constructing the 'next generation' of policies, the CPUC encounters many challenges. For example, there are equity issues associated with a socialized model, where customers share the cost of circuit upgrades as required by utilities to address increased demand in a given neighborhood: who owns the upgrade? Who can benefit? What happens when people sell their homes and move? There may be an issue of over-paying for the upgrades by home buyers or sellers of the same property over a time period. The same challenge is exasperated in condominiums (or other multi-dwelling buildings), where owners may change more often.
When residents add EV charging to the scheme, managing the home-load at night will make sense (which is the time frame that charging usually happens). From a utility stand-point, even charging at night will likely to have an impact on the life of the transformer: transformers usually cool at night, when the demand lessens. If night-time limits aren’t set by utilities, with PEV charging the transformers will not be able to cool sufficiently, resulting in extensive ware-and-tear, more frequent breakdowns, and potentially frequent maintenance or replacement. In this case, who will pay for the replacement transformers?
There are many questions than answers. By 2016, the CPUC would need to have the policies set.
1. Energy Storage North America conference website: http://www.esnaexpo.com/
2. CPUC website: http://www.cpuc.ca.gov/puc/