Power-to-gas and Power-to-liquids for Managing Renewable Electricity Intermittency in the Alpine Region

Large-scale deployment of renewable energy sources (RES) can play a central role in reducing CO2 emissions from energy supply systems, but intermittency from solar and wind technologies present grid integration challenges. High temperature co-electrolysis of steam and CO2, in the so-called power-to-gas (PtG) and power-to-liquid (PtL) configuration, could provide a path for utilizing the excess intermittent electricity from a power system by converting it into chemical fuels that can be directly utilized in other sectors, such as transportation and heating. The chemical fuels could also be used in the power sector during periods of deficit in supply. Here, we study the economic and engineering potential of PtG/PtL systems deployment as storage for intermittent renewable electricity and as a source of low-carbon heating and transportation energy among the different energy sectors in the Alpine region, using the BeWhere model, a geographic explicit cost minimization model. Preliminary results indicate large-scale deployment of the PtG/PtL technologies for producing chemical fuels from excess intermittent electricity is feasible, particularly when incentivized by carbon prices. In addition, large volumes of captured CO2, as much as 30 Mt CO2 /year are utilized in the synthesis of the chemical fuels, providing as much as 23% of liquid transportation fuels. In this context, it can be concluded that PtG/PtL technologies can enable greater integration of RES into the energy supply chain, with application worldwide

Applying potential BECCS solutions to the US coal sector: New coal boom or bust?

Coal-fired plants have been the pillar of US power generation for more than a century, still contributing nearly 40 percent to U.S. electricity supply and accounting for about a third of national CO2 emissions. Nevertheless, coal\u27s dominance in the United States is waning, mainly because new emissions regulations are changing the economics of power generation, making coal uneconomical in some areas. At the same time, according to recent scenarios of energy transition, coal will continue to play a large and indispensable role in a carbon constrained world. Indeed, the challenge for governments and industry is to find a path that mitigates carbon emissions yet continues to utilize coal to meet urgent energy needs. Biomass coupled with post-combustion carbon capture and storage (BECCS) could play an important role in deeply cutting CO2 emissions from existing coal-fired power plants. However, adding existing commercial sequestration systems to pulverized coal power plants might significantly increase the cost of electricity and lead to energy penalty. Thus, the feasibility of CCS retrofit should be evaluated on a site-specific basis so to account for varying unit characteristics. Under such premises, the main goal of this work is to identify candidate coal plants for which CCS options might be economically feasible considering different policy scenarios (e.g. increasing carbon prices) and given the presence of site specific constraints (e.g. plant maturity, biomass availability and proximity of a suitable CO2 sink). The methodology implies the adoption of the spatially explicit model BeWhere, which optimizes the cost of the entire BECCS supply chain. Three CCS options are investigated according to different carbon abatement rate: Biomass co-firing up to 15% of total output from a single coal plant with no CCS, CO2 capture and a carbon negative routes through the adoption of biomass coupled with CCS. Saline aquifers located in the US territory and currently representing over 90% of the estimated capacity, are adopted as potential storage sites. The model outputs include the number and location of feasible coal power plants, the length and diameters of CO2 pipelines as well as the location and dimension of the injection sites. The results shows that although the storage of CO2 is largely economically sustainable, the implementation of a full scale BECCS project would require the imposition of high carbon prices (approximately $70/ton). We conclude that to allow the transition of North American black fuel towards a green energy, and thus to defer both climate change and coal plants phase-out, bold policies of clear vision to include CCS in the country’s emissions reductions agenda, must be undertaken

Negative Emissions on South East Asia: Renewable Energy Optimization with BECCS for Indonesia

Indonesia, on the one hand, is a tropical country with large biomass productivity and increasing oil and gas sector activities. On the other hand, it is the 3rd largest GHG emitter globally and some 90% of its emissions are generated from massive land-use change. However, Indonesia has also developed very ambitious climate targets aiming at up to 41% emission reduction by 2020. These targets need to be balanced with an envisaged GDP growth by 7% and projected 5 times higher energy consumption in 2050. To decrease its fossil fuel dependency and emissions, the government of Indonesia has decided to increase the renewable energy supply from 6% to 23% by 2025, along with a 100 percent electrification target by 2020. Furthermore, BECCS (i.e. the combination of forest based bioenergy with carbon capture and storage) is seen as a promising tool to bridge between the various future challenges Indonesia is facing and at the same time to deliver large quantities of negative emissions needed by the end of this century. But - irrespectively of Indonesia’s abundant resources to meet ambitious renewable energy and mitigation targets - there is lack of proper integrated planning, regulatory support, investment, distribution in remote areas of the Archipelago, and missing data to back the planning. To support the government of Indonesia in its sustainable energy systems planning, a geographic explicit energy modeling approach is applied. IIASA’s BeWhere Model identifies the optimal location of energy conversion sites based on the minimization of the supply chain costs. The model incorporates the existing fossil fuel-based infrastructures, and evaluates the optimal costs, potentials and locations for the development of renewable energy technologies (i.e. wind, solar, hydro, biomass and geothermal based technologies), as well as the development of biomass co-firing in existing coal plants. An optimally adapted renewable energy mix – vis-à-vis the competing fossil fuel based resources – is identified. In addition, the in situ BECCS capacity for different scenarios is assessed for Indonesia. Special focus is put on nature protection and cultural heritage areas, where feedstock (e.g., biomass harvesting) and green-field power plant sites will be limited – depending on the protection type and renewable energy technology. First results of the study provide indications on where, how and which technologies should be implemented. Moreover, the assessment indicates that the BECCS potentials vary substantially over the different scenario assumptions. Sustainable biomass feedstock production, energy demand and supply as well as competing industries and existing transport infrastructure are key to achieve an optimal BECCS solution. Clean energy access for all with special emphasis on remote areas and small islands in Indonesia turns out to be especially interesting from a socio-economic, emission savings and innovation perspective

Power-to-gas and power-to-liquid for managing renewable electricity intermittency in the Alpine Region

Large-scale deployment of renewable energy sources (RES) plays a central role in reducing CO2 emissions from energy supply systems, but intermittency from solar and wind technologies presents integration challenges. High temperature co-electrolysis of steam and CO2 in power-to-gas (PtG) and power-to-liquid (PtL) configurations could utilize excess intermittent electricity by converting it into chemical fuels. These can then be directly consumed in other sectors, such as transportation and heating, or used as power storage. Here, we investigate the impact of carbon policy and fossil fuel prices on the economic and engineering potential of PtG and PtL systems as storage for intermittent renewable electricity and as a source of low-carbon heating and transportation energy in the Alpine region. We employ a spatially and temporally explicit optimization approach of RES, PtG, PtL and fossil technologies in the electricity, heating, and transportation sectors, using the BeWhere model. Results indicate that large-scale deployment of PtG and PtL technologies for producing chemical fuels from excess intermittent electricity is feasible, particularly when incentivized by carbon prices. Depending on carbon and fossil fuel price, 0.15−15 million tonnes/year of captured CO2 can be used in the synthesis of the chemical fuels, displacing up to 11% of current fossil fuel use in transportation. By providing a physical link between the electricity, transportation, and heating sectors, PtG and PtL technologies can enable greater integration of RES into the energy supply chain globally

Prevalence of H. pylori among asymptomatic HIV-positive and negative individuals in Central Ethiopia and efficacy of eradication therapy

OBJECTIVES: Helicobacter pylori is a widespread pathogen and major contributor to dyspeptic disease and gastric cancer. Although the interaction between HIV and H. pylori infection is not well investigated, previous studies have suggested a decreased prevalence of H. pylori and limited efficacy of eradication therapy in HIV-positive individuals. Therefore, the objectives of this study were to describe the prevalence of H. pylori infection according to HIV status and analyze the efficacy of eradication therapy in Ethiopia. METHODS: A prospective, randomized, interventional study was performed involving HIV-positive and negative participants presenting to the Asella Referral and Teaching Hospital in Central Ethiopia between March and June 2017. A stool antigen test was used as a screening tool for H. pylori infection. Randomly selected patients received triple eradication therapy. RESULTS: The cumulative H. pylori prevalence was 77.3% (392/507): 78.8% (241/306) among HIV-positive individuals versus 75.1% (151/201) among HIV-negative individuals (P = 0.386). Twenty-five HIV-positive and 26 HIV-negative H. pylori-infected participants were randomized to receive standard triple therapy; three of them were lost to follow-up (one HIV-positive, two HIV-negative). The total eradication rate was 50.0%: 62.5% (15/24) among those HIV-negative versus 37.5% (9/24) among those HIV-positive [Au?1]. CONCLUSIONS: A high prevalence of H. pylori was observed among HIV-positive and negative individuals in Central Ethiopia. The efficacy of eradication therapy was low, with a trend towards lower efficacy in HIV-infected individuals

Hydropower production benefits more from 1.5°C than 2°C climate scenario

Hydropower plays an important role as renewable and clean energy in the world's overall energy supply. Electricity generation from hydropower represented approximately 16.6% of the world's total electricity and 70% of all renewable electricity in 2015. Determining the different effects of 1.5°C and 2°C of global warming has become a hot spot in water resources research. However, there are still few studies on the impacts of different global warming levels on gross hydropower potential. This study used a coupled hydrological and techno‐economic model framework to assess hydropower production under global warming levels of 1.5°C and 2°C, while also considering gross hydropower potential, power consumption and economic factors. The results show that both global warming levels will have a positive impact on the hydropower production of a tropical island (Sumatra) relative to the historical period, however, the ratio of hydropower production versus power demand provided by 1.5°C of global warming is 40% higher than that provided by 2°C of global warming under RCP6.0. The power generation by hydropower plants shows incongruous changing trends with hydropower potential under the same global warming levels. This inconformity occurs because the optimal sites for hydropower plants were chosen by considering not only hydropower potential but also economic factors. In addition, the reduction in CO2 emissions under global warming of 1.5°C (39.06×106 t) is greater than that under global warming of 2°C (10.20×106 t), which reveals that global warming decreases the benefits necessary to relieve global warming levels. However, the hydropower generation and the reduction in CO2 emissions will be far less than the energy demand when protected areas are excluded as potential sites for hydropower plants, with a sharp decrease of 40‐80%. Thus, government policy‐makers should consider the tradeoff between hydropower generation and forest coverage area in nationally determined contributions