Abstract
Plug-in electric vehicles (PEV) are considered to be a potentially sustainable alternative to conventional vehicles for private transport and a way of balancing intermittent generation from renewable energy sources (RES). Using RES for electric mobility would be superior to all available fossil generation alternatives in terms of emissions and efficient energy conversion. To quantify the marginal energy from RES used, two charging strategies last trip charging and optimized demand-side management (DSM) with dynamic pricing are investigated for a German long-term high RES power mix scenario. The results for both charging cases indicate that the power demand for PEVs will not be met by RES. For last trip charging 1.40% comes from RES. In terms of DSM this share increases to 7.38% but results in higher overall CO2 emissions because for Germany coal provides the lowest cost fossil power. Hence DSM charging reduces peak load and helps to balance RES generation but is contrary to the original idea of clean transportation because of higher marginal emissions caused by the utilisation of coal. To account for contractual arrangements allowing consumers to directly purchase RES electricity, a second scenario with additional installed RES capacity is analysed. Because of the high RES share of over 50 % a complete usage of the RES is not possible and a small fraction of power must still be provided by dispatchable power plants. For the second scenario, DSM charging also allows for an increased use of RES compared to last trip charging (99 % versus 90% RES). In addition, total marginal CO2 emissions are lower and DSM helps to balance the ramping of RES. Therefore, it is concluded that for Germany the installation of additional RES and DSM charging would guarantee clean transportation using electric vehicles.
Highlights
The greenhouse gas emissions of plug-in hybrid electric vehicles and/or battery electric vehicles (PEVs) are unquestionably determined to a large extent by how the electricity is generated
This paper investigates the utilization of thermal power plants and renewable energy sources including and excluding the electricity demand of plug-in electric vehicles in Germany
Compared to approaches which use the average CO2 emissions of the power plant park, the methods used here allow the electricity consumption of electric vehicles to be directly assigned to individual power plants and provide much more accurate results
Summary
The greenhouse gas emissions of plug-in hybrid electric vehicles and/or battery electric vehicles (PEVs) are unquestionably determined to a large extent by how the electricity is generated. It may be deduced that RES are necessary to fuel PEVs in order to achieve a significant reduction of CO2 emissions unless nuclear power instead of coal provides most base load capacity. This paper addresses the behaviour of an electric generation mix where coal dominates current base load capacity while RES additions are considered highly desirable, so RES achieves a very high share of generation. This very high use of RES drives down the capacity utilization of base load (coal) power plants.
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