Introduction
The basic principle of the sustainable energy cycle is, the inclusion of electric vehicle as a part of a localized electric grid for a house, multiple buildings or entire community.
Majority of EV owners uses their electric vehicle during the week for shorter trips, while longer trips are done during weekend or during vacation. The EV used for the project uses a dual battery system, where first battery is used for daily driving needs, while the second battery is also a part of the energy storage of the building and is inserted back in to the vehicle only when a larger range is needed.
By increasing the energy capacity in the stationary batteries, we increase the capability of the energy storage, as it increases the efficiency of the photovoltaic system which can sustain itself for a longer periods without sun. This system can completely satisfy the energy needs of a house, if said house is a low energy user, or a vacation house, which is not used very frequently. It also reduces the cost of the stationary battery, as it is being used for the building as well as the vehicle.
We have presented the idea at WTN (World technology network summit) in New York in November 2015 and gradually building the system during 2016 till it became fully functional till the end of the year. The project is still ongoing by collecting the data and improving the system. The new addition will be “Solar van” project which will have robotized removable part of the battery that will serve as range extender or storage.
Batteries are still the most expensive part of both storage system and electric car, so double use could significantly increase both range and storage when needed. At the moment no car producer except Tesla offers a car with a range that suits long distance drives. At the same time most household storage systems serve just as buffers and not real storage due to high cost of batteries. Most of the Mo-Fri daily drives in EU 28 don’t exceed 50 km while weekend and holiday drives tend to be of greater distance. So the necessity of having a longer range is mostly limited to the time when family is not at home, what lowers the household electricity consumption at that time. That means that if electric car producers would make part of the battery in a removable form, this part could serve as additional storage for the house being totally or just partly off grid. Additional batteries for existing cars could also be produced by third parties what we have proved by adding removable 10 kWh battery that has served also as battery storage to existing VW E Golf. Besides additional electric car batteries, some existing electric vehicles that are used only during summer season like Renault Twizzy and scooters, could be connected to Sustainable energy cycle directly thus boosting the available storage capacity without any additional work or cost.
Same system can also be applied to vacation houses that are used just for holidays or weekends and could be completely off grid basically having just a small 2 – 5 kWh storage battery connected to renewable energy sources for the time the house is not in use. When the owner arrives for the weekend, part of the electric car battery is connected to the system.
In case of an off grid or partly off grid community, multiple cars are connected to local or central storage system boosting its capacity during most of the time.
Prototype
Till October 2016 we have been building a fully functional prototype of Sustainable energy cycle for a 2 family house of 7 people (5 drivers). Both families use only electric cars for daily, business, weekend and holiday driving. Removable 25 kWh battery is available for the cars to boost the range when necessary while 2 small city cars (converted electric Smarts) could be directly connected to the system when the family is using long range cars with electric range extender.
- Overall maximum storage battery capacity is 115 kWh
- Fixed storage is 50 kWh of lithium cells
- Electric range extender contains 25 kWh
- Both city cars (Smart fortwo and Smart Roadster) contain 40 kWh and could be directly connected to the system. Smart Roadster is a fun/leisure car, so it has been connected to storage during winter time.
- Annual PV electricity production is 8000 kWh, annual consumption 14000 kWh
- Storage operating voltage is 52 V (class A – not dangerous for humans)
- Maximum range of Metron 7 (converted electric car) using electric range extenders and main battery is 800 km at 70 km/h
Impact and beneficiaries
Island PV systems:
At 40 degrees latitude, a completely off grid island system needs a storage battery being 13% of annual energy consumption. So a 50 kWh storage battery would only be enough for 384 kWh annual energy consumption. Our sample sustainable energy cycle would increase storage to 75 kWh, so it would be enough for 577 kWh annual consumption or at full use 115 kW to fulfill the needs of 884 kWh annual consumption. It is enough for a weekend house or a very high efficient household. Sustainable energy cycle increases the efficiency of an island system for the same ratio as is the ratio between fixed storage and electric range extender storage. At today’s average storage batteries and EV batteries it would by average improve island system by 50%
Partly independent households or small communities:
Partly independent households or communities cover part of their energy needs by renewable power plants (PV or wind), while the rest has been taken from the grid. Especially during longer cloudy weather periods such systems lose efficiency due to low storage capacity. Table below is calculated for our sample system where during most of the months there is lack of electricity, so additional power has to be supplied from the grid. Using our sample system, we can store more energy, so during summer months we can completely cover all energy needs by PV, while during other months, we can adapt the demand for grid power according to peak and off peak hours determined by the grid operator. This sample system produces 8000 kWh of renewable energy annually and by adding additional car batteries and small cars to the system we could improve use of renewables for 32 % (time when renewable energy was available to power the house).
Larger systems to balance the grid:
Sustainable energy cycle could also improve efficiency of large systems that are being built lately to balance the grid cutting the peaks. In this case Sustainable energy cycle acts similar to V2G (vehicle to grid) system, but is more universal due to removable car battery that could be in use for storage also when cars are driving. Total impact relates to the size of large system storage and number and size of electric range extenders in use at certain community.
Additional beneficiaries
Sustainable energy cycle offers additional advantages:
- Lower energy consumption of electric vehicles at city/short distance driving due to lower weight when additional battery has been removed
- In case that electric range extenders (additional batteries) would be installed additionally by third parties, it would create jobs locally at community level in form of workshops that would install those batteries in electric vehicles.
- Electric range extenders would prolong the lifetime of electric cars as the main battery would be stressed less at long range drives due to lower C rating at same speed/power.
- Higher range of electric cars would lower the necessity of using fast DC chargers that cause energy consumption peaks that affect the grid.
- Sustainable energy cycle would boost RD and implementation of smart grids that systems will be connected to. Automation of removing and installing the additional batteries will be the next logical step.
Use of fun/leisure cars
Fun/leisure electric vehicles that are used mostly during periods of good and warm weather like Renault Twizzy, golf carts and scooters could be connected to Sustainable energy cycle directly. It would boost the available EU storage capacity during the time when most needed (winter) without much cost and effort. 18265 Renault Twizzy vehicles have been sold in EU till end of 2016. Twizzy is an open 2 seat vehicle used only in good weather when we have less need for storing photo-voltaic electricity. The total capacity of Twizzy’s in EU is 52,76 MWh considering its 6,1 kWh battery. Even if just one fifth of all those vehicles would be connected to storage systems, it would contribute to EU battery storage more than the biggest operational storage system in Feldheim, Germany having 10 MWh and costing 12,8 million €.
Battery system of those vehicles operates at same level then most commonly used storage systems for households (48 Volts DC nominal), so they could be connected without complex technical and financial investment.
There is also a certain amount (250-300) of Greenline 33 and 40 hybrid leisure boats parked during off season time (October-April) all around EU lakes. Each boat has a lithium battery of 12 kWh that could serve as storage preventing damage that is often caused at parked boats due to self discharge during off season. Due to 48V voltage they can be directly connected to the hybrid storage system (3 MWh at least).
Replication potential and social acceptance
Sustainable energy cycle could be replicated anywhere for households, weekend houses, remote farms, business facilities and communities. It seems to be very well socially accepted, as several independent environmental organizations have already supported our project: Alpe Adria Green, Bündnis Alpen Kovention Kaernten and Alpine Pearls. The most important step right now is that Sustainable energy cycle becomes recognized also by big car producers and grid operators, so that it could be built at a larger scale.
Excellence and innovation
Sustainable energy cycle is a new approach towards achieving the goals of 2020 and 2030 EU objectives. Nobody till now has used the simple fact that most of the time we use our electric vehicle only for short distances and that part of the battery can be removed and used as storage battery. Sustainable energy cycle has been presented at World Technology Network where it has been recognized as innovation in the field of “Environment”:
New York, NY (November 8th, 2015) – Today, Andrej Pecjak, was named a World Technology Award Finalist by the World Technology Network (“The WTN”) – a global community comprised of the most innovative people and organizations at the forefront of science and technology and related fields. Andrej Pecjak and has been selected as a finalist for category “Environment” for »Sustainable energy cycle«. Award winners will be revealed at the WTN’s 14th annual World Technology Summit & Awards event, held November 19-20, 2015, in the TIME Conference Center at the historic TIME & LIFE Building in New York City.
The World Technology Summit & Awards is a global gathering that brings together many of the world’s leading technologists, scientists, futurists, policymakers, entrepreneurs, and forward-thinkers for two days of talks, panel discussions and demonstrations that explore what’s groundbreaking, imminent, possible, and society-changing in emerging technologies. This year’s theme is “The Future: Who and What You Need to Know.”
Each year, the WTN recognizes the best and brightest in their fields and the organizations on the cutting edge of technological innovation. Recipients are voted on by their peers – the WTN Fellows, the winners and finalists from previous annual awards cycles – based on their outstanding contributions to technology, science and other related disciplines and the potential impact and long-term significance of their work. Thirty awards across all industries – from art and design to health and medicine to space – will be presented during a special black-tie awards gala on the closing night of the summit.
A full list of 2015 World Technology Network Award finalists can be found here: http://www.wtn.net/summit-2015/world-technology-awards-finalists
Source: http://www.wtn.net/summit-2015/webcast
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Jozef Stefan institute, Department of Inorganic Chemistry