| 1. |
- Frånlund, Maria, et al.
(författare)
-
Results from 22 years of Followup in the Göteborg Randomized Population-Based Prostate Cancer Screening Trial
- 2022
-
Ingår i: Journal of Urology. - 0022-5347 .- 1527-3792. ; 208:2, s. 292-300
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose:Our goal was to analyze results from 22 years of followup in the Göteborg randomized prostate cancer (PC) screening trial.Materials and Methods:In December 1994, 20,000 men born 1930-1944 were randomly extracted from the Swedish population register and were randomized (1:1) into either a screening group (SG) or to a control group (CG). Men in the SG were repeatedly invited for biennial prostate specific antigen testing up to an average age of 69 years. Main endpoints were PC incidence and mortality (intention-to-screen principle).Results:After 22 years, 1,528 men in the SG and 1,124 men in the CG had been diagnosed with PC. In total, 112 PC deaths occurred in the SG and 158 in the CG. Compared with the CG, the SG showed a PC incidence rate ratio (RR) of 1.42 (95% CI, 1.31-1.53) and a PC mortality RR of 0.71 (95% CI, 0.55-0.91). The 22-year cumulative PC mortality rate was 1.55% (95% CI, 1.29-1.86) in the SG and 2.13% (95% CI, 1.83-2.49) in the CG. Correction for nonattendance (Cuzick method) yielded a RR of PC mortality of 0.59 (95% CI, 0.43-0.80). Number needed to invite and number needed to diagnose was estimated to 221 and 9, respectively. PC death risk was increased in the following groups: nontesting men, men entering the program after age 60 and men with >10 years of followup after screening termination.Conclusions:Prostate specific antigen-based screening substantially decreases PC mortality. However, not attending, starting after age 60 and stopping at age 70 seem to be major pitfalls regarding PC death risk.
|
|
| 2. |
|
|
| 3. |
- Hugosson, Jonas, 1955, et al.
(författare)
-
Eighteen-year follow-up of the Göteborg Randomized Population-based Prostate Cancer Screening Trial : effect of sociodemographic variables on participation, prostate cancer incidence and mortality
- 2018
-
Ingår i: Scandinavian Journal of Urology. - : Medical Journals Sweden AB. - 2168-1805 .- 2168-1813. ; 52:1, s. 27-37
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: This study examined whether previously reported results, indicating that prostate-specific antigen (PSA) screening can reduce prostate cancer (PC) mortality regardless of sociodemographic inequality, could be corroborated in an 18 year follow-up. Materials and methods: In 1994, 20,000 men aged 50–64 years were randomized from the Göteborg population register to PSA screening or control (1:1) (study ID: ISRCTN54449243). Men in the screening group (n = 9950) were invited for biennial PSA testing up to the median age of 69 years. Prostate biopsy was recommended for men with PSA ≥2.5 ng/ml. Last follow-up was on 31 December 2012. Results: In the screening group, 77% (7647/9950) attended at least once. After 18 years, 1396 men in the screening group and 962 controls had been diagnosed with PC [hazard ratio 1.51, 95% confidence interval (CI) 1.39–1.64]. Cumulative PC mortality was 0.98% (95% CI 0.78–1.22%) in the screening group versus 1.50% (95% CI 1.26–1.79%) in controls, an absolute reduction of 0.52% (95% CI 0.17–0.87%). The rate ratio (RR) for PC death was 0.65 (95% CI 0.49–0.87). To prevent one death from PC, the number needed to invite was 231 and the number needed to diagnose was 10. Systematic PSA screening demonstrated greater benefit in PC mortality for men who started screening at age 55–59 years (RR 0.47, 95% CI 0.29–0.78) and men with low education (RR 0.49, 95% CI 0.31–0.78). Conclusions: These data corroborate previous findings that systematic PSA screening reduces PC mortality and suggest that systematic screening may reduce sociodemographic inequality in PC mortality.
|
|
| 4. |
- Pihl, Erik, 1981, et al.
(författare)
-
Biomass Retrofitting a Natural Gas-Fired Plant to a Hybrid Combined Cycle (HCC)
- 2009
-
Ingår i: 22nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2009; Foz du Iguacu, Parana; Brazil; 30 August 2009 through 3 September 2009. ; , s. 2163-2176
-
Konferensbidrag (refereegranskat)abstract
- This work investigates retrofit of a natural gas fired plant for co-firing with biomass. The retrofit is by integration of a solid biomass combustor with the bottoming cycle of a combined cycle gas turbine (CCGT) plant, to form a Hybrid Combined Cycle (HCC). The motivation is the need to find efficient options for substitution of natural gas by biomass to meet the imminent need to reduce C02 emissions as well as improve security of supply in the utility power sector, which in some regions is heavily dependent on power generation from rather new CCGT plants. The work is based on process simulations using an existing 600 MWfuel combined heat and power CCGT plant (commissioned 2006) as reference. It is shown that the HCC retrofit only yields a minor decrease in plant efficiency; electric efficiency (ηe) of 43.3%, compared to 44.4% for natural gas-only in the reference plant (full load and full substitution of supplementary firing corresponding to 39% of natural gas). A HCC with higher biomass-firing capacity and an additional high-pressure condensing turbine can increase the substitution of natural gas to 59% yielding ηe = 40.8% and total efficiency (electricity and heat) of 87.1%, i.e. a larger decrease in efficiency than for 39% substitution. A HCC plant gives in all configurations higher electric efficiency than a corresponding combination of single-fuel stand-alone plants, CCGT for naturalgas and steam CHP plants for biomass, with the same share of biomass in thefuel mix. A simulation representing one year's operation of hybrid and reference options, including part load cases, show that overall efficiencies can be kept at roughly the same levels as infull load. It is recognized that layout of existing plant, projected level of natural gas substitution and local conditions in fuel supply and energy demand are necessary to consider when assessing the most suitable option for C02 abatement by biomass in a gas power plant.
|
|
| 5. |
- Pihl, Erik, 1981, et al.
(författare)
-
Energy supply
- 2019
-
Ingår i: Exponential Roadmap Scaling up 36 solutions to halve emissions by 2030.
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The 2019 Exponential Roadmap focuses on moving from incremental to exponential climate action in the next decade. It presents 36 economically- viable solutions to cut global greenhouse gas emissions 50% by 2030 and the strategies to scale this transformation. The roadmap is consistent with the Paris Agreement’s goal to keep global average temperature “well below 2°C” and aiming for 1.5°C above pre- industrial levels. The 2019 roadmap is the second in the series. Each new roadmap updates solutions that have proven potential to scale and charts progress towards exponential scaling. The roadmap, based on the carbon law (see box) is a collaboration between academia, business and civil society. The roadmap is complemented with a high-ambition narrative, Meeting the 1.5°C Ambition, that presents the case why holding global average temperature increase to just 1.5°C above pre-industrial levels is important. Since the first roadmap, the Intergovernmental Panel on Climate Change (IPCC) published its special report on 1.5°C. The report concluded that the economic and humanitarian risks of a 2°C world are significantly higher than 1.5°C. The remaining emissions budget for 1.5°C is small, and will be exceeded within ten to fifteen years at current emission rates. The window of feasibility is closing rapidly. The global economic benefit of a low-carbon future is estimated at US$26 trillion by 2030 compared with staying on the current high-carbon pathway. The scale of transformation – halving emissions by 2030 – is unprecedented but the speed is not. Some cities and companies can transform significantly faster. Developed nations with significant historic emissions have a responsibility to reduce emissions faster. Greenhouse gas emissions, and the solutions to reduce them, are grouped by six sectors: energy, industry, transport, buildings, food consumption, nature-based solutions (sources and sinks). Meeting the 1.5°C goal means implementing solutions in parallel across all sectors. The solutions must scale exponentially. The roadmap identifies four levers required to scale the transformation as well as necessary actions for each: policy, climate leadership and movements, finance and exponential technology. Implementation must be fair and just or risk deep resistance.
|
|
| 6. |
- Pihl, Erik, 1981, et al.
(författare)
-
Highly efficient electricity generation from biomass by integration and hybridization with combined cycle gas turbine (CCGT) plants for natural gas
- 2010
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 35:10, s. 4042-4052
-
Tidskriftsartikel (refereegranskat)abstract
- Integration/co-firing with existing fossil fuel plants could give near term highly efficient and low cost power production from biomass. This paper presents a techno-economical analysis on options for integrating biomass thermal conversion (optimized for local resources 50 MW) with existing CCGT (combined cycle gas turbine) power plants (800-1400 MWth). Options include hybrid combined cycles (HCC), indirect gasification of biomass and simple cycle biomass steam plants which are simulated using the software Ebsilon Professional and Aspen Plus. Levelized cost of electricity (LCoE) is calculated with cost functions derived from power plant data. Results show that the integrated HCC configurations (fully-fired) show a significantly higher efficiency (40-41%, LHV (lower heating value)) than a stand-alone steam plant (35.5%); roughly half of the efficiency (2.4% points) is due to more efficient fuel drying. Because of higher investment costs, HCC options have cost advantages over stand-alone options at high biomass fuel prices (>25 EUR/MWh) or low discount rates (
|
|
| 7. |
- Pihl, Erik, 1981
(författare)
-
Integrating Biomass in Existing Natural Gas-Fired Power Plants
- 2010
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Using biomass for utility heat and electricity generation can supplement use of fossil fuels, whose emissions of carbon dioxide likely risk causing serious climate change and ocean acidification. Biomass as energy source is a limited resource and when used as fuel in thermal power plants this currently results in higher production costs than using fossil fuels such as natural gas and coal. It is, therefore, important to find highly efficient and reliable biomass conversion technologies. Reliability is important to minimize investment risk. Co-firing biomass with coal is well known as a potential low cost and high efficient way of introducing biomass in the stationary energy system. Yet, several regions around Europe and elsewhere are strongly dependent on natural gas for electricity generation, typically applying combined cycle gas turbine (CCGT) plants. Although CO2 emissions from natural gas is considerably lower than from coal fired plants, it is less known how to introduce biomass as fuel in natural gas fired plants than in coal. Therefore, the present thesis evaluates options for integration of thermal conversion of biomass with existing CCGT plants. The focus on existing gas fired plants is motivated by a) gas fired plants are becoming increasingly dominant in some regions and there should be sought integration options that are not only based on co-firing with coal, and b) if the existing power plant infrastructure can be used to introduce biomass this could facilitate a near term introduction of biomass, contributing to near term CO2 mitigation targets, as opposed to building biomass-only dedicated plants.The biomass-based options for CCGT integration investigated in this work are hybrid combined cycles (HCC) and biomass gasification. A HCC is a combined cycle firing various fuels; in the present case natural gas in gas turbines (GTs) as topping cycle, and biomass in a fluidized bed boiler as bottoming (steam) cycle. HCC options include fully-fired (hot windbox) schemes with uncooled flue gases from GTs used as fluidization media in boiler, and supplementary fired schemes with GT flue gas used for preheating air and economizing. Gasification means thermal conversion of biomass to producer gas, that is cleaned and upgraded to medium-value syngas or high-value methane, which can be used in GT-based plants. The gasification schemes considered in this work also include minor steam cycles. The above options are compared to power (and heat) generation in commercial state-of-the-art fluidized bed boiler steam plants, as reference. All are applied to two basic case studies (three CCGT plant concepts, based on actual/typical plants) with varying gas plant sizes and configurations with different gas turbine types and steam data, as well as in condensing or combined heat and power schemes.The results show that increased thermal and cost efficiency can be attained by some of the proposed schemes for biomass/CCGT-integration. Integrated fully-fired hybrid schemes can give an increase of the specific biomass efficiency related to electricity production in the range 4-9 %-points, and for the gasification options up to 14 %-points, compared with a stand-alone state of the art biomass boiler, which has an electrical efficiency in the order of 35 %. Gasification schemes for methane were found to be less efficient for power (and heat) production than those for medium-value syngas. Parallel-powered hybrid schemes did not show thermodynamical benefits in the studied options. Levelized cost of electricity (LCoE) for integrated options was found to be in the range of, at most, 10-20 EUR/MWh lower than non-integrated options. The best cost performance was found for options with the highest efficiencies (gasification to medium value syngas, hybrid options at some conditions) or for those with simple design at conditions of high DH prices and/or low biomass fuel costs. Drying of biomass with CCGT low temperature exhaust gases was found to be cost-efficient. Obtaining modest efficiency increase by employing more advanced technology, such as some configurations of hybrid cycles, did not show significant cost benefits. The choice of most cost effective technology was found to mainly depend on district heating prices, whereas fuel costs and discount rates had less but still important influence.The overall conclusion of this work is that biomass integration with existing combined cycle natural gas-fired plants has the potential to lower costs and increase the competitiveness for biomass power compared with other low carbon alternatives (fossil power with carbon capture), although attributed with some risks and technical difficulties. Biomass integration in existing natural gas power plants can, therefore, be part of a pathway to increase employment and development of biomass thermal conversion technologies.
|
|
| 8. |
- Pihl, Erik, 1981, et al.
(författare)
-
Material Constraints for Concentrating Solar Thermal Power
- 2012
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 44:1, s. 944-954
-
Tidskriftsartikel (refereegranskat)abstract
- Scaling up alternative energy systems to replace fossil fuels is a critical imperative. Concentrating Solar Power (CSP) is a promising solar energy technology that is growing steadily in a so-far small, but commercial scale. Previous Life Cycle Assessments (LCA) have resulted in confirmation of low environmental impact and high lifetime energy return. This work contributes an assessment of potential material restrictions for a large scale application of CSP technology using data from an existing parabolic trough plant and one prospective state-of-the-art central tower plant. The material needs for these two CSP designs are calculated, along with the resulting demand for a high adoption (up to about 8 000 TWh/yr by 2050) scenario. In general, most of the materials needed for CSP are commonplace. Some CSP material needs could however become significant compared to global production. The need for nitrate salts (NaNO3 and KNO3), silver and steel alloys (Nb, Ni and Mo) in particular would be significant if CSP grows to be a major global electricity supply. The possibilities for increased extraction of these materials or substituting them in CSP design, although at a marginal cost, mean that fears of material restriction are likely unfounded.
|
|
| 9. |
- Pihl, Erik, 1981
(författare)
-
Reducing Carbon Emissions From Natural Gas-fired Power Plants – Biomass, Concentrated Solar and Carbon Capture
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, possibilities to reduce emissions from combined cycle gas turbine (CCGT) plants are evaluated. The evaluation is done from two perspectives: techno-economic analysis, and analysis of the resource and integration potentials. Included technologies for reducing CO2 are biomass and concentrating solar power (CSP), integrated with the CCGT, as well as application of post-combustion carbon capture and storage (CCS) to the gas plant. The techno-economic analysis is based on technical options and methodology presented in three papers (Papers I, II and IV) and these options are in the thesis compared with a harmonized methodology. European potentials for integration with existing CCGT plants are assessed in the thesis by complementing database information for gas plants with solar irradiation data and satellite images. An analysis of the global material constraints of CSP is included, based on results from Paper III, and complemented with an oversight of material issues for biomass power and CCS. In addition, the thesis includes an oversight of global and European resource potentials of biomass power, CSP and CCS, based on literature review.One main conclusion of the thesis is that there are potential efficiency and cost benefits of integrating biomass and solar energy with existing natural gas-fired power plants. Solar and biomass options are both found to give up to 8-13%-points better efficiency when integrated with a triple pressure CCGT plant, than corresponding stand-alone configuration. CCS in gas plants is found to have the lowest levelized cost of electricity, LCoE (60-80 EUR/MWh), compared to biomass-based options (80-140 EUR/MWh) and stand-alone solar (>200 EUR/MWh). Biomass-gas hybrids are, however, found to be competitive with CCS options in terms of CB-E, break-even cost of CO2. Integrating CSP collectors with combined cycle plants will reduce the LCoE to almost half that of stand-alone plants (~130 EUR/MWh), nearly closing the gap to where CSP can be competitive with other low-carbon technologies. The total economic potential for biomass power is found to be about 1,000-3,000 TWhe/y in the EU. Comparable figures for CSP are 2,000-3,000 TWhe/y. The EU CO2 storage capacity is sufficient to facilitate more than 3,000 TWhe/y from natural gas CCS over a 100 year period. The European integration potential with CCGT plants is estimated to about 240 TWhe/y for biomass and 2-4 TWhe/y for concentrating solar. Material constraints should not be restrictive for significant growth or global capacity of the studied technologies. Integrating with existing CCGT plants can be viewed as a “low-hanging fruit” to reduce CO2 emissions, and build capacity and develop solar and biomass technologies.
|
|
| 10. |
- Pihl, Erik, 1981, et al.
(författare)
-
Thermo-Economic Optimization of Hybridization Options for Solar Retrofitting of Combined-Cycle Power Plants
- 2014
-
Ingår i: Journal of solar energy engineering. - : ASME Press. - 0199-6231 .- 1528-8986. ; 136:2, s. 021001-
-
Tidskriftsartikel (refereegranskat)abstract
- A thermo-economic optimization model of an integrated solar combined-cycle (ISCC) has been developed to evaluate the performance of an existing combined-cycle gas turbine (CCGT) plant when retrofitted with solar trough collectors. The model employs evolutionary algorithms to assess the optimal performance and cost of the power plant. To define the trade-offs required for maximizing gains and minimizing costs (and to identify ‘optimal’ hybridization schemes), two conflicting objectives were considered, namely, minimum required investment and maximum net present value (NPV). Optimiza- tion was performed for various feed-in tariff (FIT) regimes, with tariff levels that were either fixed or that varied with electricity pool prices. It was found that for the givencombined-cycle power plant design, only small annual solar shares (?1.2% annual share, 4% of installed capacity) could be achieved by retrofitting. The integrated solar combined-cycle design has optimal thermal storage capacities that are several times smaller than those of the corresponding solar-only design. Even with strong incentives to shift the load to periods in which the prices are higher, investment in storage capacity was not promoted. Nevertheless, the levelized costs of the additional solar-generated electricity are as low as 10 ce/kWh, compared to the 17–19 ce/kWh achieved for a reference, nonhybridized, “solar-only” concentrating solar power plant optimized with the same tools and cost dataset. The main reasons for the lower cost of the integrated solar combined-cycle power plant are improved solar-to-electric efficiency and the lower level of required investment in the steam cycle. The retrofitting of combined-cycle gas turbine plants to integrated solar combined-cycle plants with parabolic troughs represents a viable option to achieve relatively low-cost capacity expansion and strong knowledge building regarding concentrating solar power.
|
|
