This semester, I took a stats class and a very interesting class called Energy, Materials, and Manufacturing, which covered a range of sustainability-related topics. My project for that class was about grid-scale energy storage and whether or not combining storage (huge batteries, or other technologies) with renewable energy sources (such as wind and solar energy) is a viable way of reducing greenhouse gas emissions in the US. Though renewable energy generation itself is essentially carbon-free, manufacturing and implementing the storage and power generation technologies involves significant emissions when done on a massive scale and we were interested to see whether there was still a net reduction or not when taking these emissions into account.
We found that both pumped hydro energy storage and vanadium redox batteries have the potential to enable wider use of renewable energy sources while offering up to a 60% reduction in emissions as compared to current annual emission levels. However, this upper limit requires that 100% of our energy be generated from renewables (wind turbines, solar panels, etc.) instead of coal or natural gas, which is not likely to happen in the near future.We also made some significant simplifying assumptions, like ignoring the costs and logistical constraints associated with transmission. These considerations help explain why we aren't switching to renewable energy faster.
Another reason that we aren't switching to renewable energy sources faster is that non-renewable energy recently got cheaper in the United States, thanks to the natural gas boom facilitated by technology improvements in shale gas extraction, which is my main topic of research as a research assistant and PhD student at MIT. You've probably heard at least a bit about hydraulic fracturing in recent years, and it is improvements to hydraulic fracturing that has enabled better and better extraction of shale gas.
Shale gas, as the name suggests, is natural gas that is found in rock formations thousands of feet below the Earth's surface. When gas is found in conventional reservoirs, it is enough to drill a well and let the gas flow out. With shale gas, however, the flow rates are too slow for it to be worth the gas company's investment - too slow, that is, unless the well is "stimulated" by pressurizing the well with a special fluid until the rock fractures. The fracturing fluid also carries a material such as sand into the fractures to keep it propped open, and this allows gas to flow more freely.
Hydraulic fracturing has actually been around since the late 1940s - a fact that I was surprised to learn in my research this semester. One of the most significant improvements to this well stimulation method is the ability to drill directional wells. Where before, wells could only access whatever was at the bottom of a vertical well, now the wellbores can be turned horizontally and follow the relatively narrow shale zone for thousands of feet. This has significantly increased the amount of gas that can be produced by a single well and is one of the factors responsible for the increase in the projection of how much natural gas can be recovered in the US over the coming decades.
So what, specifically, am I attempting to do in my research? I am working on developing a tool that will help predict environmental risks (for now, focusing on greenhouse gas emissions) associated with shale gas extraction based on where the well is and what specific technologies are being used (there are many options, as each drilling and fracturing operation is designed specifically for a given site). It is widely agreed that natural gas will play an increasingly important role in meeting the growing energy demand in coming years, and since shale gas is what is enabling that, I am interested in contributing to solutions that help shale gas development proceed in as environmentally benign a manner as possible.
Am I a supporter of natural gas? I would say yes, especially since it is a cleaner energy source than coal, with the caveat: as long as we truly use natural gas as a bridge to more renewable energy sources. It is true that we need to buy some time as renewable energy generation and storage technologies are developed, and natural gas can help us in this regard.
I am concerned, however, that this new-found natural gas abundance will make us lazy and give us a false sense of security. Regardless of where you stand on the climate change debate, there is no denying that oil, gas, and coal are limited resources, and sooner or later we are going to have to face this fact. Sure, we can get more and more creative with how we get at these resources, but since we have already gotten to the point of literally flattening our mountains for coal and extracting gas from rock, I think there should be some red flags here. We are messing with systems that we don't completely understand and making irreversible changes that we may not see the effects of for years to come.
So I am a supporter of clean energy, and therefore I am a supporter of natural gas since it is relatively clean (especially compared to coal), but I earnestly hope for the day that natural gas has to step aside and make room for even cleaner technologies.