News & Media
Microbial diversity influences nitrogen cycling in rivers
Seasonal changes affect microbiome communities, genes, and subsurface biogeochemical pathways differently
DOE researchers investigated the role of microbial genetic diversity in two major subsurface biogeochemical processes: nitrification and denitrification. Results show that across different seasons only a few microbe species, namely Nitrosoarchaeum, carry out nitrification functions—demonstrating high resistance to environmental change. However, denitrification genes, which are more broadly distributed in the community, displayed a variety of diversity patterns and abundance dynamics—demonstrating greater microbial interactions as conditions change.
There is little research connecting microbiomes at the genetic level to hydrobiogeochemical modeling. This research helps broaden collective knowledge for a better understanding of the pathways affected by environmental changes. For example, under extreme environmental conditions an entire biochemical pathway could be altered or eliminated if a single step has low genetic diversity such that its loss could not be replaced.
The Pacific Northwest National Laboratory research team, led by Bill Nelson, found that major environmental processes—specifically nitrification and denitrification—are maintained through a variety of diversity strategies. Historically, the bulk of biogeochemical research has focused on microbial communities at the organismal level. But this research focused on the importance of genetic distribution and diversity.
In their recent PLoS ONE paper, the researchers discuss the roles microbes play in ecological functions; the novelty of the genetic makeup of these microbes; and future research opportunities to determine which organisms are genetically expressing nitrogen cycling functions.
The novelty of this study comes from examining the temporal dynamics of diversity at the gene level. To evaluate all genes in the nitrification and denitrification pathways, novel Hidden Markov Models (HMMs) were developed that can recognize the broad diversity found in environmental samples. They found that while different environmental conditions impair microbiome growth and the gene expression of some populations, at the same time, it can stimulate others. High biodiversity at the organism or genetic level creates more resiliency, and the microbiome community can respond more rapidly to environmental changes.
Bill Nelson, Pacific Northwest National Laboratory, William.Nelson@pnnl.gov
This research was supported by the U.S. Department of Energy (DOE), Office of Biological and Environmental Research (BER), as part of the Subsurface Biogeochemical Research Scientific Focus Area (SFA) at Pacific Northwest National Laboratory (PNNL).
W.C. Nelson, E.B. Graham, A.R. Crump, S.J. Fansler, E.V. Arntzen, D.W. Kennedy, J.C. Stegen, “Distinct temporal diversity profiles for nitrogen cycling genes in a hyporheic microbiome”. PLoS ONE 15(1) e0228165 (2020). [DOI: 10.1371/ journal.pone.0228165]
Peeking Into the Lives of Soil Microbiomes
SoilBox provides in-depth imaging and characterization of soil microbial communities in their native environments.
To better characterize the vast diversity of soil microbes and their interactions, DOE researchers developed a high-tech simulated soil core called SoilBox. This 16.7-centimeter-deep box allows researchers to visualize soil microbes’ complex interactions using different imaging methods and facilitating, for the first time, visualization of the soil microbiome’s organization and community metabolism. Furthermore, SoilBox provides a tool for researchers to observe how soil microbial communities respond to environmental changes and perturbations.
The complexity of soil makes spatial imaging of soil microbial communities challenging. Using SoilBox, researchers can now visualize the diversity and metabolic
landscape of the soil microbiome under different environmental conditions, such as soil moisture and temperature. Understanding the basic biology of the soil microbiome is necessary for understanding how native soil systems respond to environmental perturbations such as drought, lack of nutrients, and fire.
Soil-dwelling microbes are key players in the overall health of soil ecosystems, performing critical functions like carbon and nutrient cycling. The interplay between the soil microbiome and the soil it inhabits is a dynamic relationship heavily influenced by factors such as soil acidity, organic content, and temperature. The size and distribution of soil particles also affects many soil characteristics, adding to the already complex challenge of accurately describing structure-function relationships of soil microbial communities.
To address the difficulties of studying the soil microbiome in its native state and at a microscale resolution, a team of researchers from Pacific Northwest National Laboratory, led by Arunima Bhattacharjee and Chris Anderton, developed SoilBox. This system represents a soil ecosystem by simulating an ~12-cm-deep soil core; several windows facilitate molecular and optical imaging measurements that are crucial to understanding the nuanced interactions between the soil microbiome and its environment. This novel imaging capability allows scientists to study the dynamic landscape of soil microbial communities as they relate to environmental changes, including nutrient cycling.
This work overcomes the challenge of visualizing the diversity of soil microbial communities in the complex and ever-changing environment of soil. SoilBox will be used in the near future to investigate soil microbial community dynamics.
Chris Anderton, Pacific Northwest National Laboratory, email@example.com
This research was supported by the Department of Energy (DOE) Office of Biological and Environmental Research (BER) and is a contribution of the Scientific Focus Area "Phenotypic response of the soil microbiome to environmental perturbations." Pacific Northwest National Laboratory (PNNL) is operated for the DOE by Battelle Memorial Institute under Contract DE-AC05-76RLO1830. A portion of the research was performed using EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility sponsored by BER and located at PNNL.
A. Bhattacharjee et al.,“Visualizing microbial community dynamics via a controllable soil environment.” mSystems 5, 1:e00645-19 (2020). https://doi.org/10.1128/mSystems.00645-19.
PNNL Launches Marine Renewable Energy Database
Tethys Engineering addresses industry’s technical and engineering challenges
Marine renewable energy (MRE) has the potential to provide 90 gigawatts of power in the United States through waves and tidal and ocean currents.
To harness the ocean’s energy, the MRE industry needs to understand how to address technical and engineering challenges such as efficient power takeoff, device survivability, and grid integration.
PNNL developed Tethys Engineering in September 2019 to allow sharing resources around the deployment of devices in corrosive, high-energy marine environments. The recently launched Tethys Engineering online database includes collected and curated documents surrounding the technical and engineering development of MRE devices. Users can search and filter results to intuitively identify information relevant to developers, researchers, and regulators.
Tethys Engineering includes more than 3,000 journal articles, conference papers, reports, and presentations related to wave, current, salinity gradient, and ocean thermal energy conversion technologies. The database contains information from around the world.
The Tethys Engineering database was created as a companion to the already established Tethys website, which focuses on the environmental effects of the MRE industry.
Understanding the Grid Value Proposition of Marine Energy: A Literature Review
In 2018, the US Department of Energy’s Water Power Technologies Office Marine Hydrokinetics Program directed two national laboratories, Pacific Northwest National Laboratory and National Renewable Energy Laboratory, to investigate the potential of marine renewable resources to contribute the U.S. electric system. Due to the innovative nature of marine renewable energy and the transformation of the US electric system resource mix, there is a lack of insight about the future potential role and grid value proposition of marine energy.
An initial step in this technical project is to review available literature to inform and help characterize the portfolio of potential marine energy resource contributions. This literature review summarizes the energy fundamentals of marine resources; the performance and operational characteristics of energy conversion devices; grid opportunities and integration challenges most applicable to marine energy; storage coupling to achieve grid opportunities; and offshore wind energy competition and collaboration. It provides the context and the state of knowledge in which the grid value proposition of marine energy should be further researched and explored.
Notable findings from the review include the following:
- Very little work has been conducted to connect the grid and fundamental marine energy development. Few technical papers attempt to demonstrate grid value from marine energy or, conversely, illustrate how grid applications may have an effect on device size and scale, convergence of device types, and location of marine energy technologies. Those that have done so relied on numerous estimations and assumptions and target very specific potential benefits.
- Aggregation of tidal generation for baseload—the concept of distributing tidal generators to accomplish complementary phase shifts in generation that, when summed, would provide relatively stable power—faces challenges from a cost perspective. One study evaluated three geographically separate, complementary locations off the Scottish coast. The study concluded that aggregate power generated from sites with varying resources is sensitive to the characteristics of the individual sites and some irregularity should be expected in aggregate power output due to natural variation in successive tides. Ultimately, the study suggests that using complementary sites and limiting the capacity of the turbines, particularly during neap tides, could create baseload power, or a constant power output; but the research team expressed concerns regarding whether such a deployment would be cost effective. Decreasing the turbines’ rated capacity and therefore not capturing the resource to its fullest extent would cause economic losses.
- Tidal energy-generating profiles may be well matched for storage. Energy storage is a fast-growing resource in the energy industry. It can provide value in a multitude of grid situations, including supporting marine energy technologies. One report suggests that because tides are predictable, tidal technologies are ideal for pairing with energy storage to create a steady output of power. In fact, Nova Innovation recently integrated a Tesla battery storage system with the Shetland Tidal Array in Scotland and expanded the generating capacity and enabled dispatchability at the site.
- There is a potential match between resource peak and electric demand. When considering a seasonally peaking resource, like wave energy, there is an opportunity for the generation patterns to be well matched with energy demand. For example, one study noted that British Columbia’s energy consumption peaks in the winter when the available wave resource is also at its strongest; this same characteristic is true along the rest of North America’s Pacific Northwest coast.
- Co-location may deliver grid benefits. A study evaluating a portion of the North Sea showed that there could be significant benefits to co-locating wave devices and offshore wind turbines. When wind and waves are negatively correlated, this decreases variability and can help mitigate grid integration concerns that are sometimes associated with variable generation. Being proactive in the siting process and performing quantitative spatial planning can avoid potential conflicts between sea uses, while harnessing the most useful energy.
- The availability and cost of land was used in utility decision-making for resource selection and resulted in a portfolio selection that included marine energy development. In a 2017 Integrated Resource Plan for the Caribbean Utilities Company (the public electric utility for Grand Cayman in the Grand Cayman Islands), a contractor evaluated land use associated with different generation technologies and found a significant advantage to using marine energy, specifically ocean thermal energy conversion (OTEC). Accordingly, and despite a higher capital cost for OTEC relative to other resource options, the resource plan containing OTEC was among the two recommended portfolios. In the portfolio, OTEC resources replaced onshore solar development, which requires a relatively high land commitment proportional to total generation, as well as natural gas-fired backup generation and battery storage. Although OTEC is not considered in this report, connections can be drawn to the technology, and research from that field is applicable to other marine energy resources in particular instances.
As the marine energy industry grows, there is a corresponding increase in the body of literature about both the potential value of harnessing marine resources as well as the requisite technical work to integrate the resource into the grid. Due to the unique aspects of marine energy resources, especially their offshore location, volume, and predictability, there are many reasons to consider marine energy a viable potential renewable resource in the future electric system.
Understanding the Grid Value Proposition of Marine Energy: An Analytical Approach
The US Department of Energy’s Water Power Technologies Office (WPTO) has tasked two national laboratories, Pacific Northwest National Laboratory (PNNL) and National Renewable Energy Laboratory (NREL), to develop an understanding of the grid value proposition for marine renewable energy (MRE): how harnessing the energy of waves, tides, and ocean currents could be a meaningful and competitive source of renewable energy in the future grid.
This work will provide insights to the conditions under which MRE technologies offer unique benefits for the electricity system. PNNL and NREL will conduct a project to comprehensively review the grid value for marine renewable energy development at scale on an intermediate- to long-term horizon. The project will dovetail with nationally-accelerating valuation efforts to characterize and quantify specific services from energy resources and assess the value of those services over time. It will capitalize on the emerging concept of locational value, especially for distributed energy resources (DER), referencing adopted frameworks and related laboratory analysis. And it will take advantage of laboratory expertise in a variety of disciplines – ocean physics, mechanical and electrical engineering, energy economics – chained together in order to ensure that benefits and services assessed are realistic for MRE technologies and ocean energy resources.
The purpose of the immediate analytical approach is to outline the landscape of MRE attributes and their potential value and, at a high-level, discuss methods to quantify these values. For purposes of this investigation, the words grid value should be broadly construed. The term is meant to include, but not be limited to, provision of a defined grid service, measurable benefit to grid performance, avoided costs to system investments or operations, revenue capture, and contribution to desired grid qualities (e.g. reliability or low carbon intensity). Value can also accrue to a range of entities.
The authors intend to consider use cases and system benefits where MRE may have a competitive or unique role; and where there is a distinct and measurable value additional to energy production. To do this, the authors look beyond the typical values of energy production (a payment of cents per kilowatt-hour produced) and instead to “grid services,” those services required for the grid to operate and deliver energy to customers (i.e. unit scheduling and dispatch, reactive power and voltage control, and frequency control). Certain grid services are captured in the traditional suite of ancillary services that may be directly compensated in an organized market, and as a result many of these benefits already have highly competitive contributing generators or other electricity system assets. Therefore, in this initial exercise of considering competitive and unique benefits, the authors are less concerned with the energy (or grid service) production itself but the timing, the location, or the system condition that form measurable and distinct value.
Protecting climate-sensitive soil ecosystems
Review paper summarizes the effects of climate change on soil microorganisms and the ecosystem services they provide, and evaluates potential mitigation measures.
Researchers from Pacific Northwest National Laboratory reviewed the current state of knowledge about the impacts of climate change on soil microorganisms in different climate-sensitive soil ecosystems. They also examined the possibilities of using soil microorganisms to store carbon or inoculate plants to help mitigate the negative consequences of climate change. Based on their review, the authors recommend an integrated approach that combines beneficial properties of soil microorganisms with sustainable soil management practices to support plant production, maintain a clean water supply, sustain biodiversity, store carbon, and increase resilience in the face of a changing climate.
The effects of climate change on soil microbial communities have potentially large consequences for Earth's soil ecosystems and the beneficial services that soil microbiomes provide. This review highlights the need to connect the fine-scale details arising from microbiome studies to the landscape-scale resolution of many Earth system climate models in the search for climate change mitigation measures.
On Earth’s terrestrial surface, the soil microbiome cycles nutrients to sustain plant and animal life. While this microbial community is innately connected to environmental conditions, impacts on the soil microbiome due to climate change vary depending on the ecosystem. Different aspects of climate change impact soil microbial communities and their important ecosystem functions, such as cycling of carbon and supporting plant growth. But the molecular details of soil biochemical reactions responsible for these key functions are largely unknown.
Researchers synthesized existing knowledge of climate change impacts across a range of soil environments—permafrost, forests, grassland, wetlands, and deserts—to examine how the microbiome responds. They looked at microbial changes coinciding with different climate change variables including increases in carbon dioxide levels, temperatures, drought, flooding, and fires. Their review showed that microbial physiology largely determines the ability of soil ecosystems to adapt, and that some microbiomes may be suitable for climate change mitigation measures such as carbon sequestration and promoting plant growth. The review sets the stage for future research on soil microbiomes and challenges to overcome in order to connect to larger-scale predictive models of climate change.
Janet Jansson, Lab Fellow, firstname.lastname@example.org
Kirsten Hofmockel, Earth Scientist, email@example.com
This research was supported by the Department of Energy Office of Biological and Environmental Research (BER) Genomic Science Program and is a contribution of the Scientific Focus Area "Phenotypic response of the soil microbiome to environmental perturbations." PNNL is operated for DOE by Battelle Memorial Institute under Contract DE-AC05-76RLO1830. A portion of the research was performed using the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility sponsored by BER and located at PNNL.