•Deep direct-use projects were evaluated for heating, cooling and thermal storage.•Performance was compared with non-geothermal systems and other countries.•Subsurface, surface and financial ...conditions significantly impact feasibility.•Attractive levelized costs of energy found for heating, cooling and thermal storage.
This paper investigates the techno-economic feasibility of geothermal deep direct-use for heating, cooling, and thermal energy storage in the United States. The six 2017–2019 deep direct-use projects funded by the U.S. Department of Energy are reviewed and evaluated using the simulation tool GEOPHIRES, and results are compared with prior studies, existing geothermal district heating systems in Europe and the United States, as well as non-geothermal centralized and non-centralized heating, cooling, and thermal energy storage systems. Analysis indicates that deep direct-use feasibility varies widely, depending on subsurface characteristics, system design, and financial conditions. Project base case levelized cost of heat values ranged between $13 and $350/MWh; key drivers lowering the levelized cost of heat include higher reservoir temperatures, shallower reservoir depths, higher well flow rates, higher utilization rates, lower drilling costs, and lower discount rates. Incentives such as grants and an investment tax credit resulted in small improvements in project economics. Base case levelized cost of heat values for four projects fell within the range of levelized cost values for existing systems in Europe and the United States, and were comparable to values found in previous studies, including the 2019 GeoVision study. The lowest-cost projects for district heating had comparable levelized cost of heat values to existing fossil-fuel-driven district heating systems, and lower values than decentralized heating with natural gas boilers or heat pumps. Chilled water production with absorption chillers driven by a high-quality geothermal resource obtained attractive levelized cost of cooling values, in line with values from typical centralized cooling production facilities and lower than domestic decentralized cooling with air-conditioning units. Also, thermal energy storage is a potential deep direct-use application, where levelized cost of storage values can be obtained that are comparable to those of other thermal storage techniques such as borehole thermal energy storage and hot water storage tanks. Other aspects of deep direct-use, which are not captured in a standard levelized cost of energy metric, include the ability to decarbonize the heating and cooling supply, and provide reliability and resiliency to the energy infrastructure. These attributes are gaining increased attention and improve overall project feasibility. Finally, this paper identifies technical, market, policy, and social barriers for deep direct-use development in the United States, and provides potential approaches for reducing these barriers.
This paper investigates the techno-economic feasibility of geothermal deep direct-use for heating, cooling, and thermal energy storage in the United States. The six 2017–2019 deep direct-use projects ...funded by the U.S. Department of Energy are reviewed and evaluated using the simulation tool GEOPHIRES, and results are compared with prior studies, existing geothermal district heating systems in Europe and the United States, as well as non-geothermal centralized and non-centralized heating, cooling, and thermal energy storage systems. Analysis indicates that deep direct-use feasibility varies widely, depending on subsurface characteristics, system design, and financial conditions. Project base case levelized cost of heat values ranged between $13 and $350/MWh; key drivers lowering the levelized cost of heat include higher reservoir temperatures, shallower reservoir depths, higher well flow rates, higher utilization rates, lower drilling costs, and lower discount rates. Incentives such as grants and an investment tax credit resulted in small improvements in project economics. Base case levelized cost of heat values for four projects fell within the range of levelized cost values for existing systems in Europe and the United States, and were comparable to values found in previous studies, including the 2019 GeoVision study. The lowest-cost projects for district heating had comparable levelized cost of heat values to existing fossil-fuel-driven district heating systems, and lower values than decentralized heating with natural gas boilers or heat pumps. Chilled water production with absorption chillers driven by a high-quality geothermal resource obtained attractive levelized cost of cooling values, in line with values from typical centralized cooling production facilities and lower than domestic decentralized cooling with air-conditioning units. Also, thermal energy storage is a potential deep direct-use application, where levelized cost of storage values can be obtained that are comparable to those of other thermal storage techniques such as borehole thermal energy storage and hot water storage tanks. Other aspects of deep direct-use, which are not captured in a standard levelized cost of energy metric, include the ability to decarbonize the heating and cooling supply, and provide reliability and resiliency to the energy infrastructure. These attributes are gaining increased attention and improve overall project feasibility. Finally, this paper identifies technical, market, policy, and social barriers for deep direct-use development in the United States, and provides potential approaches for reducing these barriers.
•We successfully modified the PFA methodology to identify favorable areas for superhot EGS at Newberry Volcano in 3D.•Key components of superhot EGS plays were developed, including heat source, ...thermal insulation, and producibility.•Uncertainty was also quantified in 3D for datasets which provided enough information to do so.•Two different methods were used to weight exploration datasets, and the resulting favorability models compared.
The DErisking Exploration for multiple geothermal Plays in magmatic ENvironments (DEEPEN) project aims to de-risk exploration of geothermal plays in magmatic systems, with a focus on superhot and supercritical geothermal systems. This article presents advancements in geoscientific assessment of superhot enhanced geothermal system (EGS) resources as part of the DEEPEN project, particularly in exploration and identification of these systems. While there exists a general consensus on key components of conventional hydrothermal systems, there has not been a prior consensus on such components for EGS, let alone superhot EGS. The DEEPEN project identified these key components for superhot EGS plays, and used them to modify the traditional geothermal play fairway analysis (PFA) approach to identify favorable areas in superhot EGS plays in 3D. This was done through modeling both favorability and uncertainty separately for each key component of a superhot EGS play, incorporating diverse 3D geoscientific datasets, including geologic features, models produced from direct observations, single inversions, and joint inversions. The PFA is applied to Newberry Volcano as a form of validation. The results appear to validate the methodology, aligning with expectations derived from conceptual modeling, and highlighting the area targeted for EGS stimulation well NWG 55-29 as favorable, and suggesting potential additional areas worthy of exploration at Newberry.
The DErisking Exploration for multiple geothermal Plays in magmatic ENvironments (DEEPEN) project aims to de-risk exploration of geothermal plays in magmatic systems, with a focus on superhot and ...supercritical geothermal systems. This article presents advancements in geoscientific assessment of superhot enhanced geothermal system (EGS) resources as part of the DEEPEN project, particularly in exploration and identification of these systems. While there exists a general consensus on key components of conventional hydrothermal systems, there has not been a prior consensus on such components for EGS, let alone superhot EGS. The DEEPEN project identified these key components for superhot EGS plays, and used them to modify the traditional geothermal play fairway analysis (PFA) approach to identify favorable areas in superhot EGS plays in 3D. This was done through modeling both favorability and uncertainty separately for each key component of a superhot EGS play, incorporating diverse 3D geoscientific datasets, including geologic features, models produced from direct observations, single inversions, and joint inversions. The PFA is applied to Newberry Volcano as a form of validation. Finally, the results appear to validate the methodology, aligning with expectations derived from conceptual modeling, and highlighting the area targeted for EGS stimulation well NWG 55-29 as favorable, and suggesting potential additional areas worthy of exploration at Newberry.
To undertake the first systematic review examining the performance of artificial intelligence (AI) applied to cross-sectional imaging for the diagnosis of acquired pulmonary arterial hypertension ...(PAH).
Searches of Medline, Embase and Web of Science were undertaken on 1 July 2020. Original publications studying AI applied to cross-sectional imaging for the diagnosis of acquired PAH in adults were identified through two-staged double-blinded review. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies and Checklist for Artificial Intelligence in Medicine frameworks. Narrative synthesis was undertaken following Synthesis Without Meta-Analysis guidelines. This review received no funding and was registered in the International Prospective Register of Systematic Reviews (ID:CRD42020196295).
Searches returned 476 citations. Three retrospective observational studies, published between 2016 and 2020, were selected for data-extraction. Two methods applied to cardiac-MRI demonstrated high diagnostic accuracy, with the best model achieving AUC=0.90 (95% CI: 0.85-0.93), 89% sensitivity and 81% specificity. Stronger results were achieved using cardiac-MRI for classification of idiopathic PAH, achieving AUC=0.97 (95% CI: 0.89-1.0), 96% sensitivity and 87% specificity. One study reporting CT-based AI demonstrated lower accuracy, with 64.6% sensitivity and 97.0% specificity.
Automated methods for identifying PAH on cardiac-MRI are emerging with high diagnostic accuracy. AI applied to cross-sectional imaging may provide non-invasive support to reduce diagnostic delay in PAH. This would be helped by stronger solutions in other modalities.
There is a significant shortage of research in this important area. Early detection of PAH would be supported by further research advances on the promising emerging technologies identified.
Valproate is a first-line treatment for patients with newly diagnosed idiopathic generalised or difficult to classify epilepsy, but not for women of child-bearing potential because of teratogenicity. ...Levetiracetam is increasingly prescribed for these patient populations despite scarcity of evidence of clinical effectiveness or cost-effectiveness. We aimed to compare the long-term clinical effectiveness and cost-effectiveness of levetiracetam compared with valproate in participants with newly diagnosed generalised or unclassifiable epilepsy.
We did an open-label, randomised controlled trial to compare levetiracetam with valproate as first-line treatment for patients with generalised or unclassified epilepsy. Adult and paediatric neurology services (69 centres overall) across the UK recruited participants aged 5 years or older (with no upper age limit) with two or more unprovoked generalised or unclassifiable seizures. Participants were randomly allocated (1:1) to receive either levetiracetam or valproate, using a minimisation programme with a random element utilising factors. Participants and investigators were aware of treatment allocation. For participants aged 12 years or older, the initial advised maintenance doses were 500 mg twice per day for levetiracetam and valproate, and for children aged 5–12 years, the initial daily maintenance doses advised were 25 mg/kg for valproate and 40 mg/kg for levetiracetam. All drugs were administered orally. SANAD II was designed to assess the non-inferiority of levetiracetam compared with valproate for the primary outcome time to 12-month remission. The non-inferiority limit was a hazard ratio (HR) of 1·314, which equates to an absolute difference of 10%. A HR greater than 1 indicated that an event was more likely on valproate. All participants were included in the intention-to-treat (ITT) analysis. Per-protocol (PP) analyses excluded participants with major protocol deviations and those who were subsequently diagnosed as not having epilepsy. Safety analyses included all participants who received one dose of any study drug. This trial is registered with the ISRCTN registry, 30294119 (EudraCt number: 2012-001884-64).
520 participants were recruited between April 30, 2013, and Aug 2, 2016, and followed up for a further 2 years. 260 participants were randomly allocated to receive levetiracetam and 260 participants to receive valproate. The ITT analysis included all participants and the PP analysis included 255 participants randomly allocated to valproate and 254 randomly allocated to levetiracetam. Median age of participants was 13·9 years (range 5·0–94·4), 65% were male and 35% were female, 397 participants had generalised epilepsy, and 123 unclassified epilepsy. Levetiracetam did not meet the criteria for non-inferiority in the ITT analysis of time to 12-month remission (HR 1·19 95% CI 0·96–1·47); non-inferiority margin 1·314. The PP analysis showed that the 12-month remission was superior with valproate than with levetiracetam. There were two deaths, one in each group, that were unrelated to trial treatments. Adverse reactions were reported by 96 (37%) participants randomly assigned to valproate and 107 (42%) participants randomly assigned to levetiracetam. Levetiracetam was dominated by valproate in the cost-utility analysis, with a negative incremental net health benefit of −0·040 (95% central range −0·175 to 0·037) and a probability of 0·17 of being cost-effectiveness at a threshold of £20 000 per quality-adjusted life-year. Cost-effectiveness was based on differences between treatment groups in costs and quality-adjusted life-years.
Compared with valproate, levetiracetam was found to be neither clinically effective nor cost-effective. For girls and women of child-bearing potential, these results inform discussions about benefit and harm of avoiding valproate.
National Institute for Health Research Health Technology Assessment Programme.
Levetiracetam and zonisamide are licensed as monotherapy for patients with focal epilepsy, but there is uncertainty as to whether they should be recommended as first-line treatments because of ...insufficient evidence of clinical effectiveness and cost-effectiveness. We aimed to assess the long-term clinical effectiveness and cost-effectiveness of levetiracetam and zonisamide compared with lamotrigine in people with newly diagnosed focal epilepsy.
This randomised, open-label, controlled trial compared levetiracetam and zonisamide with lamotrigine as first-line treatment for patients with newly diagnosed focal epilepsy. Adult and paediatric neurology services across the UK recruited participants aged 5 years or older (with no upper age limit) with two or more unprovoked focal seizures. Participants were randomly allocated (1:1:1) using a minimisation programme with a random element utilising factor to receive lamotrigine, levetiracetam, or zonisamide. Participants and investigators were not masked and were aware of treatment allocation. SANAD II was designed to assess non-inferiority of both levetiracetam and zonisamide to lamotrigine for the primary outcome of time to 12-month remission. Anti-seizure medications were taken orally and for participants aged 12 years or older the initial advised maintenance doses were lamotrigine 50 mg (morning) and 100 mg (evening), levetiracetam 500 mg twice per day, and zonisamide 100 mg twice per day. For children aged between 5 and 12 years the initial daily maintenance doses advised were lamotrigine 1·5 mg/kg twice per day, levetiracetam 20 mg/kg twice per day, and zonisamide 2·5 mg/kg twice per day. All participants were included in the intention-to-treat (ITT) analysis. The per-protocol (PP) analysis excluded participants with major protocol deviations and those who were subsequently diagnosed as not having epilepsy. Safety analysis included all participants who received one dose of any study drug. The non-inferiority limit was a hazard ratio (HR) of 1·329, which equates to an absolute difference of 10%. A HR greater than 1 indicated that an event was more likely on lamotrigine. The trial is registered with the ISRCTN registry, 30294119 (EudraCt number: 2012-001884-64).
990 participants were recruited between May 2, 2013, and June 20, 2017, and followed up for a further 2 years. Patients were randomly assigned to receive lamotrigine (n=330), levetiracetam (n=332), or zonisamide (n=328). The ITT analysis included all participants and the PP analysis included 324 participants randomly assigned to lamotrigine, 320 participants randomly assigned to levetiracetam, and 315 participants randomly assigned to zonisamide. Levetiracetam did not meet the criteria for non-inferiority in the ITT analysis of time to 12-month remission versus lamotrigine (HR 1·18; 97·5% CI 0·95–1·47) but zonisamide did meet the criteria for non-inferiority in the ITT analysis versus lamotrigine (1·03; 0·83–1·28). The PP analysis showed that 12-month remission was superior with lamotrigine than both levetiracetam (HR 1·32 97·5% CI 1·05 to 1·66) and zonisamide (HR 1·37 1·08–1·73). There were 37 deaths during the trial. Adverse reactions were reported by 108 (33%) participants who started lamotrigine, 144 (44%) participants who started levetiracetam, and 146 (45%) participants who started zonisamide. Lamotrigine was superior in the cost-utility analysis, with a higher net health benefit of 1·403 QALYs (97·5% central range 1·319–1·458) compared with 1·222 (1·110–1·283) for levetiracetam and 1·232 (1·112, 1·307) for zonisamide at a cost-effectiveness threshold of £20 000 per QALY. Cost-effectiveness was based on differences between treatment groups in costs and QALYs.
These findings do not support the use of levetiracetam or zonisamide as first-line treatments for patients with focal epilepsy. Lamotrigine should remain a first-line treatment for patients with focal epilepsy and should be the standard treatment in future trials.
National Institute for Health Research Health Technology Assessment programme.
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