ERE
Energy, Resources and the Environment

Early Career Scientists

Student reporter for ERE at the 2016 GA

This year we will have our own student reporter, Lindsey Higgins, from Stockholm University, at the EGU GA. Lindsey will be reporting on research presented in the ERE sessions on this blog and social media. Please let us know if you think you have a suitable session for Lindsey to attend and report on. Here is some more about Lindsey and her motivations!

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Blog by Lindsey Higgins

As far back as I can remember, I have always felt drawn to the sciences. Fortunately, I had encouraging teachers when I was young and strong mentors throughout my university years. When choosing my degree program as an undergraduate, Physical Geography seemed like a perfect fit. It provided me with the opportunity to study a variety of topics and to really refine my research interests. At Buffalo State College in New York I chose a concentration of meteorology and climatology while also studying for a minor in Anthropology. This combination was the start of my interest in the intersection of human activity and environmental variability.

After taking part in any research project I could get myself into as an undergraduate, I felt the experience and drive necessary to further my academic career. At The Ohio State University I had the privilege of a research assistantship at the Byrd Polar Research Center in the Ice Core Climatology group. After working with a strictly climatological project for my Master’s degree, I was ready to move back into research that brought in the aspect of human involvement in the environment.

Currently, I am a PhD student at Stockholm University working with a crater lake in northern Tanzania. In my dissertation research, I use lake sediment to reconstruct past variability and remote sensing to look at modern fluctuations in the size of this lake. As this lake is an important freshwater resource for the people living around it, I became very interested in how it is affected by activities in the surrounding area and began collaborating with social scientists. If you are interested in this work, I will be presenting on Tuesday at 13.45 in room -2.47 during the session “Narrowing the gap: palaeoenvironment and human interaction during Late Quaternary” (CL1.06/GM6.9).

Aside from my research interests, I also find myself drawn to science communication and outreach. This is what led me to apply for a student reporter position at EGU. I often find myself asking how as researchers, we can translate our work to make it more understandable for the general public as well as people in positions to impact environmental policy development. It is my hope that after I complete my doctoral program, I can continue to be involved with this bridge between scientific research and public outreach.

I am grateful for this opportunity to report for the Energy, Resources and the Environment division and looking forward to sharing my experience at this year’s General Assembly!

LHiggins

Opportunity for Early Career Scientists

The Energy Resources and Environment Division of the EGU are looking to appoint an Early Career Scientist (ECS) representative in 2016. ECS make up a significant proportion of the EGU membership and it’s important to us that their voices are heard. ECS representatives are the link between the Union and its ECS membership. They give a voice to early career researchers and ensure their needs are met at the Assembly, and throughout the year.

The exact role and tasks of the ECS representative is not fixed but might include running the ERE Division blog, representing the ERE ECS within the ECS group and working with the ERE Committee. The appointment will be made at the EGU General Assembly, 17-22nd April, 2016 and will be for two years. A shadowing opportunity is available at the GA 2016.

If you would like to apply please send your CV and a cover letter with your reasons for wishing to represent ECS in the ERE Division to the Division President, Professor Christopher Juhlin (Christopher.Juhlin@geo.uu.se) by 1st April 2016. If you would like further information please contact the current ECS representative Sian Loveless (sian@bgs.ac.uk). Please forward this opportunity to anyone you think might be interested.

Change to Early Career Scientist definition

Change to Early Career Scientist definition

Earlier this year the term Young Scientist (YS) was replaced by Early Career Scientist. Now, in a positive move, the EGU Council has approved a change to the definition of an ECS.

Previously the definition of an ECS was:

A scientist who is 35 years old* or younger, AND who can be an undergraduate or postgraduate (Masters/PhD) student or who has received his or her highest degree (e.g., BSc, MSc, PhD) within the past seven years*.
* Where appropriate, up to one year of parental leave time may be added per child.

However, feedback from early career scientists at the 2014 and 2015 Young Scientists Forums, supported by the findings of the Young Scientist Survey of 2014, highlighted that ECS benefits are important at the onset of an academic career, independent of the age of the recipient. Taking into account this view, the EGU Council has approved a new definition which is inclusive of those who start their research career later on in life.

The new definition reads as follows:

An Early Career Scientist (ECS) is an undergraduate or postgraduate (Masters/PhD) student or a scientist who has received his or her highest degree (BSc, MSc, or PhD) within the past seven years*.
* Provided parental leave fell into that period, up to one year of parental leave time may be added per child, where appropriate.

For more information contact

Laura Roberts
EGU Communications Officer (early career scientists’ contact person at the EGU Office)
Munich, Germany
Tel: +49-89-2180-6717
Email: roberts@egu.eu

Drilling into magma: the future of electricity production from volcanic geothermal systems?

Words on Wednesday aims at promoting interesting/fun/exciting publications on topics related to Energy, Resources and the Environment. If you would like to be featured on WoW, please send us a link of the paper, or your own post, ERE.Matters@gmail.com

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Citation: Scott, S., Driesner, T. & Weis, P. Geologic controls on supercritical geothermal resources above magmatic intrusions. Nature Communications. 6:7837 doi: 10.1038/ncomms8837 (2015)

Blog by Samuel Scott

Electricity production from high-enthalpy geothermal systems typically involves drilling boreholes into permeable reservoirs at depths of 1-2 km and temperatures between 250-300 °C. The fluid that comes up the wellbore consists of a mixture of liquid and vapor, from which the vapor is separated and passed through a steam turbine to generate on average 3-5 MW per well. The Iceland Deep Drilling Project (IDDP) was founded by a group of international scientists who sought to drill to deeper, hotter conditions where water is a single-phase, intermediate density, supercritical fluid. Basic thermodynamic considerations suggest that wells drilled into supercritical geothermal resources could potentially provide an order of magnitude more electricity than a conventional geothermal well. A plan was developed to drill a borehole to 4-5 km depth in the Krafla geothermal system, with the aim of discovering a reservoir at supercritical temperatures (>374 °C) and pressures (>220 bars).

Transparent, opalescent steam discharges from the IDDP-1 borehole at the Krafla volcano in Iceland. (Image: Kristján Einarsson/IDDP)

Transparent, opalescent steam discharges from the IDDP-1 borehole at the Krafla volcano in Iceland. (Image: Kristján Einarsson/IDDP)

Drilling was difficult and did not go as expected. After chunks of quenched glass began to come up the wellbore, they knew that they had drilled into a magmatic intrusion located around 2 km depth. Studies of the glass showed that it was rhyolitic in composition. Temperature measurements suggested a fluid temperature as high as 450 °C, but since the intrusion was encountered at a relatively shallow depth, the fluid pressure was less than the supercritical pressure, and the fluid was categorized as ‘superheated steam’. The big surprise was the fact that the fluid reservoir was nonetheless much more powerful than typical wells drilled to 2 km depth. As can be seen in videos taken during the well testing (https://vimeo.com/28453850), the well discharged large volumes of translucent and opalescent fluid – classic indicators of a supercritical fluid. Well tests indicated that the well could potentially generate 35 MWe of electric power, roughly an order of magnitude greater than a typical geothermal well. However, there were many questions that surrounded this discovery. How did this fluid reservoir form? How could it form at such a shallow depth? It was unclear whether the IDDP reservoir was an anomaly, or whether similar resources could exist in other high-enthalpy systems.

This led myself and a group of collaborators at ETH Zurich to use numerical models to understand the hydrology of the IDDP reservoir. The computer code had already been successfully applied to understand high-temperature fluid flow in other settings, such as mid-ocean ridges and the formation of copper-rich porphyry deposits. We set-up the model such that only a few key parameters were needed, aimed at capturing the main sources of geologic variability between different geothermal settings. The key data that go into the model are the depth of the intrusion, the host rock permeability (a measure of how fractured the system is as a result of tectonic activity) and the brittle-ductile transition temperature (which determines the temperature where rock becomes impermeable due to plastic deformation closing connecting fluid flow pathways).

These models show how these primary geologic controls determine the extent and thermal conditions of supercritical reservoirs. For example, our study identified a brittle-ductile transition temperature greater than 450 °C as a key control on reservoir formation. Since basalt has a brittle-ductile transition temperature >450 °C, while granite becomes impermeable around 360 °C, we expect that the best resources will be found in basaltic rocks. Additionally, if the rock surrounding the intrusion is very permeable, we expect the supercritical resources to be close to the intrusion, relatively limited in spatial extent, and at temperatures near 400 °C. If the rock surrounding the intrusion is moderately permeable, the reservoirs will be larger and at higher temperatures. However, the fluid production rate for a well drilled into a supercritical reservoir will be higher when rock permeability is higher. Thus, there is a trade-off between fluid temperature and well productivity that is governed primarily by rock permeability. These basic concepts can inform future efforts to discover and exploit these resources.

SamScottFigure

If the rock (white) surrounding an impermeable body of magma (grey) is only highly permeable, supercritical water (red) is restricted to a thin layer around the magma (left panel). However, if the rock is moderately permeable, a large area can be heated to supercritical conditions (right panel). (Illustration: from Scott et al. 2015, Nature Comm.)

Our models were able to reproduce measured data from the IDDP well when the geologic controls are set to appropriate values for the Krafla system. This supports the model set-up, as well as the conclusion that supercritical geothermal resource properties depend on geologic controls. Moreover, the models show that conventional geothermal resources result simply from the mixing of supercritical fluids ascending from the intrusion and cooler fluids circulating near the intrusion but not heated to supercritical conditions. This is a new way to look at conventional high-enthalpy geothermal reservoirs.

In future studies, we will seek to better understand the role of supercritical water in controlling the thermal structure and temporal evolution of high-enthalpy geothermal systems. As our understanding progresses, we will move towards modeling specific geologic settings, including the Reykjanes geothermal system where the next IDDP well will be drilled. Since the Reykjanes geothermal field contains groundwater that is known to have a large seawater component, fluid salinity is likely to play a key role on supercritical resource formation and properties. Salt changes the thermodynamic properties of water such as density and viscosity and allows boiling to occur at higher temperatures and pressures than for pure water. This may affect the formation of similar supercritical reservoirs in unexpected ways.

Although this was not the outcome the IDDP expected, the fact that such a reservoir was encountered on the first intentional effort suggests they may be a common feature that we have been passing up by targeting reservoirs at shallower depths. It also means that targeting supercritical geothermal resources may be even more economically attractive than expected by the IDDP, since wells do not need to be drilled as deep as expected. Exploiting supercritical water resources has the potential to massively improve the economics of power production from magma-driven geothermal systems. Time will tell whether or not they can be found in systems all over the world, but we anticipate that the search for these fluid reservoirs will continue.