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An unlikely energy source for charging EVs

Published by , Senior Editor
World Pipelines,

Stephen Richards, Vice President of Engineering at Sapphire Technologies writes: Electricity demand is set to increase by 38% by 2035, according to a study by Princeton University. One notable factor driving the increase in electricity demand in the US: electric vehicles (EVs). By 2030, data from BloombergNEF shows just over 50% of passenger cars in the US will be EVs’ capacity to accommodate EV demand, they pose certain challenges like intermittency and urban availability.

For example, since many EV drivers charge overnight, evening peaks are misaligned with solar supply. MIT researchers estimate that if left unchecked this trend could lead to the need to install more than 20% more capacity to meet peak demand. However, there are clean energy sources that can help supplement renewable energy in both urban and rural locations, that could help solve gaps in capacity at peak charging hours. One such solution involves leveraging energy wasted in the natural gas supply chain. Energy is wasted at both pressure letdown stations in pipelines across the US and at wellheads. Turboexpander-generators have emerged as a reliable and emission-free method for generating clean electricity from pressure letdown processes both in pipelines and at the wellhead. With energy recovery systems like Sapphire Technologies FreeSpin® In-line Turboexpander producing up to 2.6 GWh of clean energy each year per system, there is a unique opportunity for the natural gas industry to offer a supply solution to meet the demand of EVs in the future.

Building out the grid to support EVs is going to be a costly and time-consuming endeavour. According to analytics company Kevala, California’s utility companies alone will have to spend US$50 billion to support distribution grid updates. Renewable energy sources like solar and wind could theoretically be used to expand capacity for the national grid without increasing emissions, however, relying on these energy sources to support EV demand poses numerous challenges – intermittency and geography being perhaps the two most significant. Supply of renewable energy tends to peak during daytime hours, which could run counter to EV demand. According to a 2023 JD Power study, 83% of EV drivers do their charging at home – which tends to happen overnight. Additionally, if renewables were to be used to expand grid capacity this would also include building out high voltage transmission lines from remote wind and solar plants to demand centres, which, according to CNBC, involves lengthy regulatory processes and complex financing.

Some have suggested that EVs themselves could be a potential solution to grid flexibility. For example, a recent Bloomberg article discusses the potential to incentivize UK EVs to scale up/down demand depending on grid load. Yet, this would put an additional planning burden on EV drivers, especially commercial fleets already operating on tight profit margins. And, if the grid goes down due to extreme weather, cybersecurity threats, or aging infrastructure challenges, EVs would still be left stranded. Another potential solution to balancing the increased demand from EVs involves vehicle-to-grid technology that enables an EV to act as a storage device and allows for the bi-directional flow of energy between an EV and the grid. However, while an intriguing technology, this option is at best long-term due to technological and regulatory hurdles.

A more realistic approach to supporting the increased demand from EVs on the grid involves the trend toward localised power generation. A microgrid is a self-sufficient energy system, often combining hybrid energy sources, that covers a smaller geographic footprint. Microgrids are an environmentally and economically appealing solution for EV charging for several reasons. To start, they help protect the grid from EV load growth and protect EVs from being stranded during potential grid outages and from shouldering the burden of peak pricing. Remote microgrids also help bridge the gap in EV charging stations in locations that are too far to be connected to the main electricity grid. Microgrids also provide easier opportunities to incorporate clean energy sources.

According to the Center for Climate and Energy Solutions, as of the start of 2023 the US had 692 microgrids installed, with a total capacity of nearly 4.4 gigawatts. Renewables like solar and wind energy are often used as energy sources for microgrids – especially remote grids. However, there is another clean energy source, with a comparable LCOE, that can be used to back up the intermittent supply of wind and solar energy for microgrids and to provide an energy source for microgrids in locations where solar and wind are less accessible. This energy source is derived from converting wasted pressure energy into clean electricity through the use of turboexpander generators. For example, Sapphire Technologies FreeSpin® In-line Turboexpander (FIT) can be installed at the hundreds of thousands of pressure letdown stations in natural gas pipelines and at wellheads to convert energy wasted in pressure reduction processes into electric power without interrupting operations. With about 3 million miles of natural gas pipeline in the US, for example, FIT installed at pressure letdown stations across the country have the potential to power microgrids in both urban and rural locations.

Although microgrids currently account for a small fraction of the total US electricity generation, less than 1% according to the Center for Climate and Energy Solutions, they are projected to grow rapidly by nearly 20% year-on-year through the remainder of this decade. Microgrids typically range from a few hundred kilowatts to a few megawatts. Each FIT can generate 300kW of clean electricity and many locations can support multiple units. As an example, several of the projects are for eight units making 2.4 MW total capacity. Based on data from the Department of Energy on EV electricity consumption/miles and average American driving habits, an analysis by Sapphire Technologies shows that one FIT unit could supply enough electricity to charge about one thousand electric vehicles every day. If the demand on the microgrid dips below the generating capacity of the installed FIT systems, the flow control valve can be modulated and some of the flow diverted around the turboexpander. Alternatively, the FIT can be combined with a Battery Energy System (BES) to store the excess electricity when the microgrid demand is low and to boost the electricity when the demand is high.

Not only would leveraging wasted pressure energy from natural gas pipelines to charge EVs have a positive impact on emissions reduction in the transportation sector, but also it affords pipeline operators the opportunity to monetise otherwise wasted pressure energy. With federal legislation like the Inflation Reduction Act (IRA) providing incentives for EV adoption and EV infrastructure buildout, and specific states providing incentives for microgrids development (California, Connecticut, Massachusetts, New Jersey, and New York), the cost of financing such projects could potentially be significantly offset. Moreover, they would provide natural gas operators with a vested interest in electrification of the transportation sector.

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