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Although algae are often grown at pH values between 6 and 8, shifting to more alkali or acidic conditions may benefit CO 2 delivery to algal cultures. To assess the impact of culture pH on growth rate and uptake of CO 2, we grew three relatively fast growing acidophilic (Coccomyxa sp., Euglena mutabilis and Euglena gracilis) and three alkaliphilic (Thalassiosira pseudonana, Phaeodactylum tricornutum, Chlamydomonas sp.) algal species at pH values near neutral and near the extreme of their growth range. All six species showed similar growth and CO 2 uptake ability at extreme as at neutral pH values. Cultures of the alkaliphilic species captured a higher proportion of CO 2 from the gas stream than the acidophilic species; removing 50 to 65% of CO 2 from air compared to only 38% removed by acidophilic species (or 10–24% from CO 2 enriched air). Alkaliphilic species did not become carbon limited when fed CO 2 at the concentration provided by air (0.04% CO 2), but produced less biomass and captured less total CO 2 (0.06 to 0.08 g CO 2 per day) than the acidophilic species (0.6–0.8 g CO 2 day −1) which required CO 2 enriched air to avoid carbon limitation. Bicarbonate feeding reduced the loss of CO 2 to the environment, compared to feeding gaseous CO 2, but with a potential cost in reduced specific growth rate or biomass production.

The Nordic countries constitute a natural location for the development and deployment of Bio-Energy with Carbon Capture and Storage (BECCS). Finland, Sweden and Denmark are world-leading with respect to heat and power generation from sustainable biomass. Norway is world-leading with respect to Carbon Capture and Storage (CCS). The Nordic countries also have ambitious targets for reductions of their CO2 emissions, host leading technology providers, and have large biomass potential per capita. System studies suggest that bioenergy could be the single largest energy carrier in the Nordic countries by 2050. Negative CO2 Emissions with Chemical Looping Combustion of Biomass is a multi-partner project with the goal to develop new technology that: i) enables CO2 capture and negative CO2 emissions at the lowest possible cost, ii) is able to produce power and steam for industrial and other applications, iii) utilizes Nordic expertise in fluidized bed technology and iv) has potential to achieve improved fuel utilization. The technology capable of achieving these goals is Chemical-Looping Combustion of biomass (Bio-CLC). The article presents the project and features some early results from its implementation.

In the framework of the CCSP R&D program, the regulatory gaps have been assessed at VTT using the current monitoring rules for capture, pipeline transportation and geological storage of CO2 as a benchmark. The scope of the presented work includes: (i) definition of CO2 emissions from ship transportation of CO2; (ii) review of EU regulations on MRV of maritime CO2 emissions; and (iii) review of the MRV regulation on capture, transport and geological storage of CO2 under the EU-ETS. The considered activities related to ship transportation of CO2 are liquefaction and intermediate storage with recirculation loop for boil-off CO2, loading and unloading facilities and CO2 transportation and handling during the ship voyage. Identification of the regulatory gaps, based on the above, shows what is needed to enable ship transportation of CO2 for geological storage in Europe. Based on the results, maritime transportation for CCS could be made possible with very limited new emission monitoring and verification practices. Also the trade-offs of using an MRV regulation analogous to pipeline transportation of CO2 is discussed in the results.

In this work, a concept for producing calcium carbonate from argon oxygen decarburisation (AOD) slag was further developed. In addition, its economic and environmental feasibility was evaluated. In the studied case, a stainless steel plant generating AOD slag and a paper plant requiring calcium carbonate are situated at a relatively close distance. The studied concept uses ammonium chloride as solvent for extracting calcium from the slag. In a subsequent step, the extracted calcium reacts with CO2 in lime kiln flue gas and precipitates as calcium carbonate. First, an industrial application of the concept was designed including the following units: a reverse osmosis unit enabling better recovery of ammonium chloride, an evaporator for removing excess water from the process, and a scrubber for removing ammonia vapours from the flue gases. The process was modelled, after which the investment costs and operational costs were estimated, and its environmental footprint was assessed. The results indicate that the process could in its current stage of development be economic for producing calcium carbonate for replacing ground calcium carbonate used by paper mills. If the net annual profit would be used as payment on the investment, the payback period would be 2.2 years. As the process consumes CO2 the process would have negative CO2 emissions, avoiding 0.3 t CO2 per tonne calcium carbonate produced.

The EC 2030 Framework acknowledges that CCS may have an important role in reducing direct emissions from industrial processes on the scale needed in the longer term. In this paper the potential of applying different CCUS concepts to different industrial applications in Finland has been evaluated from both the economic performance as well as the emission reduction potential point of view. The overall CO 2 emissions from industry as well as the heat and power sector in Finland were in 2013 about 52 Mt of which the estimated biogenic emissions comprise about 24 Mt. The results from this work show that with a CO 2 emission allowance price of 50 €/t, CCS would be economically feasible for 8 Mt CO 2 /a, covering transport and storage costs. Most of the cost-effective CCS applications in Finland would be in the biomass power & heat sector and in the pulp and paper industry. However, this requires that “negative” emissions from bio-CCS are acknowledged and included in the EU emission trading system. CCS does not provide a simple solution to reduce CO 2 emissions in Finland as there are no suitable formations for CO 2 storage, which means that CO 2 export would be required. However, a range of CO 2 utilisation options could be attractive.

Silica is commonly used as an ingredient in the coatings of inkjet papers because of its capability to provide a coating layer structure combining a high pore volume, into which all the applied inkjet ink can transfer, and a suitable pore size distribution for very quick ink absorption. Nowadays, the production of silica pigment is quite expensive, and therefore, it would be advantageous to find a cheaper raw material source. In this study, the raw material was Greek olivine from magnesite mine sidestreams. The silica pigment was produced at laboratory scale by using nitric acid as a solvent. The target of this work was to clarify how this produced silica pigment is suited for inkjet coating pigments. The coating colors were applied by a laboratory rod coater on fine base paper and white-top kraftliner, and the coated surfaces were printed with a home and office area inkjet printer. The results showed that the produced olivine-based silica pigment has a potential in matt inkjet coatings. The coating of the produced silica pigment increased the print density, decreased the print-through, and diminished the bleeding of fine paper and white-top kraftliner board. However, further development work is needed to improve the pigment brightness to a more acceptable level, and to control the particle size at the nitric acid dissolution.

Ink-jet printing technology is expected to continue growing, but cheaper silica pigment formulations than those currently available on the market will be needed for it to be commercially viable. The target of this work, part of the EU FP7 project ProMine, is to study the possibility of generating low-cost silica pigment from silicate mining industry sidestreams for use as a coating pigment for ink-jet paper. The worldwide resources of olivine are abundant and olivine is one of the main minerals in the dunite deposits in Greece. In this study silica is produced from Greek olivine silicate mineral by an acidic dissolution method. The pigment and coating layer properties of produced silica are compared to commercial silica pigments. The laboratory scale study shows that the coating of produced silica pigment has ink-jet ink absorption speed and pore structure close to commercial precipitated silica coating. Produced silica pigment coated papers are matt, having very low gloss. Results show that produced silica pigment has potential for use as matt ink-jet coating pigment.

A new 10-50 kWth scale dual fluidized bed (DFB) chemical looping combustion (CLC) process development unit (PDU) applicable for biomass was constructed during 2015-16, located in VTT's new piloting center Bioruukki in Finland. The DFB-CLC test rig consists of a circulating fluidized bed (CFB) air reactor interconnected with a bubbling fluidized bed (BFB) fuel reactor. A set of tests were carried out with ilmenite as oxygen carrier, using white and black wood pellets as fuels. The main targets were to study main operational and process parameters for CLC using biomass-based fuels with a high volatile content. Another interest was to assess the risk for high-temperature corrosion in the flue gas path of the air reactor to evaluate the possibility for improving power generation efficiency by using enhanced steam values. The DFB-PDU was operated with biofuel in total for 16 h for 9 tests. The main challenge encountered was an insufficient bed temperature of the fuel reactor (900-950ºC targeted, 840-860ºC achieved) causing a relatively high oxygen demand (29-41%). The main reason for this was that the DFB-PDU was originally designed for gasification. A clear dependency of the fluidization velocity on the CO2 capture efficiency and oxygen demand was found and explained. As the fuel is fed and gasified in the fuel reactor, fuel leakage to the air reactor was low and alkaline components were not accumulated to the surface of oxygen carrier particles, it can be concluded that concentrations of vaporized alkali chlorides components in air reactor flue gas are much lower than in conventional biomass combustion applications. The results indicate that the risk of high-temperature corrosion of superheater tubes is lower in bio-CLC than conventional biomass combustion, making it possible to to use higher steam values (temperature, pressure) in bio-CLC improving the power generation efficiency from biomass.

In this paper, the possibilities and conditions for CCS applications in Finland are assessed. The study includes an overview of Finland's current climate and energy policy framework, mapping of large CO2 emission point sources and identification of possible CO2 transportation and storage alternatives. The future role of CCS in the Finnish energy system is further assessed with energy and emission scenarios created with a comprehensive model called TIMES-Nordic. There are several large CO2 emission sources in Finland that could be potential candidates for CCS, including steel works, power and heat generating plants, as well as oil refineries. In 2008, the 12 largest facilities in the Finnish emission trading registry accounted for 30% of the total CO2 emissions in Finland. Since the Finnish bedrock is not suitable for large-scale geological storage of CO2, captured CO2 would most likely have to be transported to the North Sea or Barents Sea for long-term storage. Most of the largest CO2 emitting facilities are located on the coast line of Finland, which facilitates transportation of CO2 by ship. The current Finnish climate and energy policy largely focuses on increasing the share of renewable energy and nuclear power in energy conversion, which leaves less room for CCS. The preliminary results from the scenario calculations indicate that the share of CO2 mitigation by CCS in Finland would be less than 10 Mt/a CO2 by 2050. However, Finland has also large, stationary CO2 emissions originating from biomass combustion in the pulp and paper industry. When assuming that biogenic CO2 emissions would be included into the emission trading system, the CCS potential rises up to 18 Mt/a CO2 by 2050.

Carbon dioxide mineral sequestration is not as widely advocated as CO2 sequestration by other means such as underground storage alternatives, yet it possesses properties (capacity, permanency, energy economy) that can not be matched by other options. In this paper, our findings and results since GHGT-8 as well as current activities and near-future plans regarding CO2 mineral carbonation are presented. The focus lies on the use of fluidised bed (FB) reactors for the carbonation of magnesium silicates via magnesium oxide or magnesium hydroxide intermediates, at temperatures and pressures up to 600 ∘C, 100 bar (allowing for both sub- and supercritical conditions for CO2), supported by earlier experiments using pressurised thermogravimetric analysis (PTGA). In addition, as the production of reactive magnesium from silicate mineral is not straightforward, it receives special attention, and first results of magnesium hydroxide production from serpentine using different methods are presented.

Fixing carbon dioxide (CO2) as carbonates using silicate-based materials is an interesting alternative option for storage of carbon dioxide. Suitable magnesium-rich rocks are distributed throughout the world. The magnesium silicate deposits in Eastern Finland alone could be sufficient for storing 10 Mt CO2 each year during a period of 200–300 years. Rocks potentially suitable for carbonation are already mined, processed, piled, and stored at mines producing industrial minerals and metals. Two process schemes were constructed based on previous experimental results with producing magnesium carbonates from serpentinite, a serpentine ore. The thermal stability of the produced hydromagnesite was also assessed using thermogravimetric analysis. Although pure hydromagnesite can be produced that is thermally stable up to 300 °C, the process scheme studied requires recycling of large amounts of sodium hydroxide and acid. Since the current methods for recycling the spent chemicals are expensive and would presumably cause CO2 emissions due to power consumption, the process studied might be suitable for producing valuable mineral and metal products from serpentinite, but probably not for CO2 capture and storage.

In this work we study the possibility of utilizing steel converter slag, a byproduct of steel manufacturing, for production of pure calcium carbonate. The dissolution of calcium from steel converter slag by using acetic acid as a solvent and the precipitation of pure calcium carbonate from the resulting solution were experimentally investigated. It was found that, while strong solutions of acetic acid dissolve most of the calcium from the slag, weak acetic acid solutions dissolve calcium selectively. Precipitation of any substantial amount of calcium carbonate was found to require the addition of sodium hydroxide. Calcium conversion from the solution into the precipitate was as high as 86%, and the purity of the precipitate was over 99%. The calcium carbonate particles produced at low temperatures were found to have rhombohedral particle shapes, a very high brightness (98.7%), and a small particle size (mean value of 0.6 μm).

Carbonation of magnesium silicates offers an interesting option for CO2 emission mitigation in Finland, a country with large resources of serpentine-type minerals. Wet processes using aqueous solutions show reasonable chemical kinetics combined with poor energy economy. A dry, gas–solid process with slower chemical kinetics (demonstrated previously), but better energy economy could be an alternative. This paper addresses the energy economy of a two- or three-stage gas–solid process for magnesium silicate carbonation. It involves production of reactive magnesium as magnesium oxide or hydroxide in an atmospheric pressure step, followed by carbonation at elevated pressures that allow for reasonable carbonation reaction kinetics under conditions where magnesium carbonate is thermodynamically stable. For a feasible large-scale process the kinetics in the individual reactors must be fast enough, while the heat produced in the carbonation step must be sufficient to compensate for energy inputs to the preceding step(s). Results give reactor temperature combinations that allow for operation at a negative or zero energy input, for given carbonation reactor pressure and degree of carbonation conversion, and other process energy requirements. Softwares used were HSC and Aspen Plus. Also, some results from gas–solid kinetics studies with magnesium oxide-based materials at the pressures considered are included.

Industrial waste materials, such as steelmaking slags, appear to be potential raw materials for reducing CO2 emissions by carbonation. The suitability of applying a carbonation route based on acetic acid leaching to produce carbonates from blast furnace slag is presented in this study. The effect of solution pH, temperature, and CO2 pressure on the precipitation of carbonates was experimentally studied. A simple thermodynamic model was used to verify our results. The feasibility of the process was also discussed, addressing energy input requirements and the consumption of chemicals. According to our experiments, the addition of NaOH, i.e. an increase in solution pH, is required for the adequate precipitation of calcium carbonate at temperatures of 30–70 °C and pressures of 1 or 30 bar. Preliminary process calculations showed that approximately 4.4 kg of blast furnace slag, 3.6 l of acetic acid, and 3.5 kg of NaOH would be required to bind 1 kg of CO2, resulting in 2.5 kg of 90% calcium carbonate. While the heat needed for the evaporation of the acetic acid could probably be acquired as waste heat by process integration with other processes, the electricity required for NaOH regeneration would make the process unsuitable for CO2 sequestration.

An approach to capture and storage of CO2 by precipitation of magnesium carbonate was experimentally studied using aqueous solutions prepared from serpentinite. Serpentinite was first dissolved in 4 M HCl or HNO3 at 70 °C, after which the excess quantity of solvent was evaporated and the precipitated magnesium salt was mixed with water. CO2 gas was bubbled through the solution, while the alkalinity of the solutions was controlled using NaOH. A solution pH of 9 was found to be the optimal alkalinity for precipitation of magnesium carbonates from the solution. At this pH, the highest purity of the carbonate product (99 wt.% hydromagnesite), highest amount of CO2 fixed as carbonate (37 wt.% CO2 in precipitate), lowest net requirements of NaOH, as well as the highest conversion of magnesium ions to carbonate (94 wt.%) were obtained. Relatively pure iron oxide (88 wt.%) and amorphous silica (82 wt.%) were separated at various stages of the procedure. The high requirements of NaOH (2.4 tonne per tonne CO2 stored) and make-up acid (2–4 tonne per tonne CO2 stored) seem to be the largest obstacles to overcome for application of this approach as a CO2 storage process. © 2007 Elsevier B.V. All rights reserved.

Abundant resources of magnesium silicates make an interesting prospect for long-term storage of CO2 by mineral carbonation. Several carbonation processes proposed in literature for CO2 storage employ extraction of silicate minerals using a liquid solvent. In this study, the dissolution of natural serpentinite in respective solutions of acids, bases and ammonium salts has been investigated. Experiments performed at room temperature showed that H2SO4 was most efficient at extracting magnesium from serpentinite, followed by HCl, HNO3, HCOOH and CH3COOH. Experiments for determining the dissolution kinetics was performed at temperatures of 30, 50 and 70 °C in 2 M solutions of H2SO4, HCl, and HNO3. At 70 °C temperatures all magnesium was extracted from serpentinite in each of the three acid solutions tested during 1–2 h. Also a large part of iron in serpentinite was extracted, while very little silicon dissolved (b4%). The dissolution rate seemed to be limited by product layer diffusion for serpentinite particles with a size distribution of 74–125 μm. The apparent activation energies were 68 kJ mol −1 for dissolution in H2SO4, 70 kJ mol −1 for dissolution in HCl, and 74 kJ mol −1 for dissolution in HNO3.

A promising option for long-term storage of CO 2 is to fixate carbon dioxide as magnesium- and calcium carbonates. Slags from iron and steel works are potential raw materials for carbonation due to their high contents of calcium silicates. Precipitated calcium carbonate (PCC) is used as filler and coating materials in paper. If slag could be used instead of limestone for producing PCC, considerable energy savings and carbon dioxide emissions reductions could be achieved. In this paper, the leaching of calcium from iron and steel slags using acetic acid was investigated. Thermodynamic equilibrium calculations at atmospheric gas pressures showed that extraction of calcium is exothermic and feasible at temperatures lower than 156 °C, while the precipitation of calcium carbonate is endothermic and feasible at temperatures above 45 °C. The formation of calcium- and magnesium acetate in the solution was found to be thermodynamically possible. Laboratory-scale batch experiments showed that iron and steel slags rapidly dissolve in acetic acid in a few minutes and the exothermic nature of the reaction was verified. While silicon was successfully removed by filtration using solution temperatures of 70–80 °C, further separation methods are required for removing iron, aluminum and magnesium from the solution.

The objective of the present study was to set up a small-scale pilot reactor at ONGC Hazira, Surat, for capturing CO2 from vent gas. The studies were carried out for CO2 capture by either using microalgae Chlorella sp. or a consortium of microalgae (Scenedesmus quadricauda, Chlorella vulgaris and Chlorococcum humicola). The biomass harvested was used for anaerobic digestion to produce biogas. The carbonation column was able to decrease the average 34 vol.% of CO2 in vent gas to 15 vol.% of CO2 in the outlet gas of the carbonation column. The yield of Chlorella sp. was found to be 18 g/m2/day. The methane yield was 386 l CH4/kg VSfed of Chlorella sp. whereas 228 l CH4/kg VSfed of the consortium of algae.

Carbonation of magnesium and calcium silicates has emerged as an interesting option for long term storage of captured CO2. However, carbonated minerals are not stable in acidic environments. This study was conducted to determine if synthetically carbonated minerals dissolve in acidic rain and release CO2. Synthetic magnesium and calcium carbonates were leached in nitric acid solutions of various acidities, as well as rainwater, and the stability of the minerals was investigated with various methods. The experimental study was complemented with thermodynamic equilibrium calculations using Gibbs energy minimization software (HSC 4.0). The leaching of base ions from the two carbonate minerals was found to behave similarly and depend mainly upon the acidity of the solution. The fraction of Mg and Ca dissolved after several days of stabilization in separate solutions with initial pH 1 was 9% for both carbonates, while the fraction of dissolved minerals in a solution with initial pH > 2 was less than 1%. FT-IR analyses of the reactor atmosphere revealed that CO2 gas was more rapidly released from calcium carbonate than from magnesium carbonate. However, only 1.5% of the CO2 stored in the calcium carbonate was released as gas at pH 1 against 0.0% for magnesium carbonate. No notable CO2 release occurred when leaching magnesium and calcium carbonates in solutions of pH 2. The solid residue analyses showed that the fixed CO2 content of the carbonates that had been exposed to nitric acid was even higher than before the treatment.

Carbon dioxide emissions to the atmosphere can be reduced by chemical fixation in organic or inorganic carbonates. Many compounds can be commercially produced on an industrial scale using CO2, allowing for turning a (nowadays problematic) waste gas into economic profit. Besides this, the carbonation of magnesium silicates and calcium silicates is an option for long-term storage of CO2 at a capacity that exceeds that of other options for CO2 storage by several orders of magnitude, with the inherent benefit that post-storage monitoring of the stored CO2 is not necessary. The first part of this paper gives an overview of commercial carbonate chemical production routes that do (or in a near future can) make use of the CO2 that is produced at a large scale from human activities. The second part addresses the process technology, market potential and other aspects of mineral carbonation for long-term CO2 storage as an alternative for, for example, storage in underground aquifers.

The possibilities for reducing carbon dioxide emissions from the pulp and paper industry by calcium carbonation are presented. The current precipitated calcium carbonate (PCC) production uses mined, crushed calcium carbonate as raw materials. If calcium silicates were used instead, carbon dioxide emissions from the calcination of carbonates would be eliminated. In Finland, there could, thus, be a potential for eliminating 200 kt of carbon dioxide emissions per year, considering only the PCC used in the pulp and paper industry. A preliminary investigation of the feasibility to produce PCC from calcium silicates and the potential to replace calcium carbonate as the raw material was made. Calcium carbonate can be manufactured from calcium silicates by various methods, but only a few have been experimentally verified. The possibility and feasibility of these methods as a replacement for the current PCC production process was studied by thermodynamic equilibrium calculations using HSC software and process modelling using Aspen Plus®. The results from the process modelling showed that a process that uses acetic acid for extraction of the calcium ions is a high potential option for sequestering carbon dioxide by mineral carbonation. The main obstacle seems to be the limited availability and relatively high price of wollastonite, which is a mineral with high calcium silicate content. An alternative is to use the more common, but also more complex, basalt rock instead.

This paper describes modifications to improve the feasibility of a pre-combustion CCS concept for a gas turbine combined cycle. A natural gas-fired greenfield combined heat and power (CHP) plant equipped with pre-combustion capture was used as a base case, for which various improvement options were identified, assessed and selected. The base case was modified using the selected improvement options, after which the investment costs were re-evaluated. The results showed that the investment cost can be reduced with 8 % by excluding the pre-reformer and the low temperature water-gas-shift reactor from the reforming process. The exclusion of the pre-reformer did not affect the performance of the plant, but the exclusion of the low temperature water-gas-shift reactor led to higher CO2 emissions.

Hiilidioksidin talteenottoa ja varastointia (CCS) pidetään kansainvälisesti yhtenä merkittävimmistä tulevaisuuden hiilidioksidipäästöjen vähentämiskeinoista. Myös Suomessa kiinnostus CCS:ään on herännyt.