Synopsis
Going "all in" with electric vehicles (EVs) has the potential to significantly reduce energy resource consumption and greenhouse gas (GHG) emissions in the US and other countries. A scenario where EVs are powered with energy produced using RNG(renewable natural gas) is compelling. An EV initiative by itself is an energy efficiency play with the potential to reduce annual US energy consumption by as much as 11% and provide cost-savings to consumers. That scenario is significatively improved when EVs operate using green electricity produced by utilizing RNG. It is feasible to realize disruptive reductions of 25% in US GHG emissions economically. It is notable that utilization of RNG for EV energy production avoids egregious land use challenges but other green energy sourcescan be substituted if appropriate.
Introduction
Sustainability engineering can be a complicated enterprise given the myriad of constraints that must be addressed in conjunction with a seemingly complex and diverse assortment of solutions that are available. A couple of considerations must be first and foremost as one approaches framing problem solutions:
- Rarely are genuine sustainability solutions implemented using a "One size fits all" protocol. A certain level of customization generally is required, particularly in addressing aggregate energy and resource balances.
- Expect the unexpected. When integrating two process platforms, one may be able to realize fortuitous synergies. For example, bioconversion systems can produce RNG, hydrogen, and fertilizers while solving regional water problems.
Closer inspection shows that there is much more to the EV sustainability value proposition than meets the eye. This realization may not even be apparent to EV aficionados. The key takeaway for EV architecture is, first and foremost, that it is a compelling energy-efficiency play for societal functionality.
Thus, with just the basic strategy of reducing energy consumption, one realizes lower GHG emissions. However, by also simultaneously incorporating the use of a green energy source such as RNG for generating electricity to power EVs, it is feasible to achieve even much greater aggregate emissions reductions.
Assessing Potential EV/RNG Impact on US GHG Emissions Reduction
The basic strategy with EVs and RNG is to utilize RNG to make green electricity. A basic value proposition is devised by analyzing the basic metric that apply to this situation.The key assumptions are:
- The number of automobile miles driven in the US per year the associated amount of carbon dioxide GHG generated per mile.
- The amount US GHG carbon dioxide emissions by the US in one yearwhich is around 4,800 million metric tons of CO2 while global emissions are 36,300 million metric tons.
- Assume that an EV/RNG configuration can effectively eliminate automotive GHG emissions. This is stated because they EVs already are more energy efficient than gasoline autos and green electricity can be generated using a green energy source such as RNG.
The graph below shows total US CO2 GHG emissions, total US CO2 automobile GHG emissions, and US CO2 GHG emissions with elimination of automobile emissions.
The depicted results show a reduction of total US CO2 emissions of 27% (((4800-3485)/4800) x100) which is probably closer to 25% if one assumes some inefficiencies. Obviously, these projections are an ambitious stretch goal. Nevertheless, it is uncommon in the climate change/sustainability arena where one initiative can realize large impact on emissions while simultaneously bringing economic efficiencies. Consequently, even more "modest" goals in this situation suggest the possibility of double-digit reductions in emissions while preserving economic efficiency.
50:50 RNG/NG and Other RNG/NG Blend Scenarios
As an example, consider 50/50 RNG/NG (natural gas) or 25/75 mixtures. RNG can be generated at existing anaerobic digester installations where it can be blended with natural gas that is extracted from existing deposits. A simplified analysis performed with the help of the data shown in the graph above suggests that:
A 50/50 RNG/NG blend used to power EVs would result in US emissions reduction of almost 14% while a 25/75 RNG/NG blend realizes US emissions reduction of over 9%.
It is important to appreciate that the emissions reductions achieved by either one of the blended scenarios is noteworthy, if not hugely impressive. Consequently, the strategy of providing power to EVs using green energy is compelling on many levels.
Summary
Formulating groundbreaking sustainability and climate change initiatives requires perseverance, technical acuity, and a bit of luck. Achieving such goals can be as elusive and rare as witnessing a planetary alignment in the solar system. The opportunity to integrate two existing platforms, EVs and RNG/NG, that are demonstrated, have considerable existing infrastructure, and a respectable track record is even more fortuitous and attractive. In summation, analysis shows that using RNG or blends of RNG and NG to provide energy for EVs can achieve double digit reductions in US GHG emissions while providing energy efficiency. By having existing infrastructure in conjunction with experiential gravitas lowers both the costs and risks for embarking on this initiative.