This study quantifies the technical, economic and environmental performance of hybrid systems that use either a tidal stream or wind turbine, alongside short-term battery storage and back-up oil ...generators. The systems are designed to partially displace oil generators on the island of Alderney, located in the British Channel Islands. The tidal stream turbine provides four power generation periods per day, every day. This relatively high frequency power cycling limits the use of the oil generators to 1.6 GWh/year. In contrast, low wind resource periods can last for days, forcing the wind hybrid system to rely on the back-up oil generators over long periods, totalling 2.4 GWh/year (50% higher). For this reason the tidal hybrid system spends £0.25 million/year less on fuel by displacing a greater volume of oil, or £6.4 million over a 25 year operating life, assuming a flat cost of oil over this period. The tidal and wind hybrid systems achieve an oil displacement of 78% and 67% respectively (the same as the reduction in carbon emissions). For the wind hybrid system to displace the same amount of oil as the tidal hybrid system, two additional wind turbines are needed. The ability of the battery to store excess turbine energy during high tidal/wind resource periods relies on opportunities to regularly discharge stored energy. The tidal hybrid system achieves this during slack tides. Periods of high wind resource outlast those of high tidal resource, causing the battery to often remain fully charged and excess wind power to be curtailed. Consequently the wind hybrid system curtails 1.9 GWh/year, whilst the tidal turbine curtails 0.2 GWh/year. The ability of the tidal stream turbines to reduce curtailment, fuel costs and carbon emissions may provide a case for implementing them in hybrid systems, if these benefits outweigh their relatively high capital and operating expenditure.
There has been a growing interest in tidal-stream energy, with most past studies focusing on assessing the potential resource of sites with fast tidal currents in relatively shallow water. Regions ...with less energetic tidal currents, but in deeper waters, have been overlooked. One potential tidal-stream energy region, which fits this categorization, is the Gulf of California. In this paper we quantify the theoretical tidal-stream energy resource in this region. The resource is estimated with an unstructured depth-averaged hydrodynamic model. We find that the highest flow speeds of 2.4 m/s occur in the channel between San Lorenzo and San Esteban Island, and three lower-velocity potential sites are identified in the channels between: (1) Baja California Peninsula and San Lorenzo Island; (2) San Esteban and Tiburon Islands and (3) Baja California Peninsula and Angel de la Guarda Island. Although peak kinetic power density in these regions is found to be relatively low (∼3–6 kW/m2), the large water depth (100–500 m), results in an undisturbed theoretical annual mean power of between 100 and 200 MW. We therefore find the tidal energy resource to be large, but new turbine technologies would be required to exploit these ‘next generation’ resource regions.
•Gulf of California (México) simulated with a barotropic model.•Predicted peak tidal flows between 1.0 and 2.4 m/s at sites in the Gulf of California.•Theoretical tidal-stream power density estimates at four sites were ∼3–6 kW/m2.•Potential tidal stream sites in deep water (100–500 m).•New technologies would be required to exploit these non-traditional regions.
The extraction of tidal energy from head differences represents a predictable and flexible option for generating electricity. Here, we investigate the generation potential of prospective tidal power ...plants in the UK. Originally conceived as separate projects, operating these schemes as a cooperative system could prove beneficial. Combined with the inherent operational flexibility of tidal range-based schemes, a notable tidal phase difference in selected sites allows for the system to spread power generation over a larger proportion of the day. Using depth-averaged modelling and gradient-based optimisation techniques, we explore how a flexible cumulative operation schedule could be applied to provide a degree of continuous supply if desirable. While fully continuous operation is not achieved, a number of different optimisation schedules deliver cumulative continuous supply for over half of the year. The average minimum cumulative power output on these days is consistently over 500 MW out of a total installed capacity of 6195.3 MW. Furthermore, by introducing financial incentives associated with reliable, baseload supply, we provide an economic assessment of the tidal power plant system. The daily minimum cumulative power output determines income in the modelled idealised baseload market, while excess supply is traded in an hourly variable wholesale energy market. Results indicate that subsidies would be required in order to make a pursuit of continuous generation financially advantageous over energy maximisation strategies.
A small library of carriers consisting of various combinations of the cell penetrating peptide TAT, the SV40 Large T protein nuclear localisation signal (NLS) and a cationic dendrimer of 7 lysine ...residues (DEN) was synthesised and each member was tested for its ability to deliver exogenous DNA to human HeLa cells. We found that the TAT peptide was essential, but not sufficient for efficient uptake of exogenous DNA. The addition of either NLS or DEN significantly enhanced uptake and expression with the most active carrier consisting of the TAT, NLS and DEN peptides. For those peptides that facilitated DNA uptake, the complexes were targeted to intracellular compartments that required incubation with a fusogenic agent such as chloroquine before gene expression was observed. However, our data suggest that chloroquine did not enhance expression solely by promoting endosomal release since a fusogenic peptide derived from the influenza virus haemagglutinin protein did not improve gene expression. Chloroquine was found to protect DNA from degradation and enhance transcription of DNA bound to the respective carriers. Our results demonstrate that multi-component peptide-based gene carriers can be designed to deliver exogenous DNA. The actions of lysosomotropic agents such as chloroquine reveal the multifactorial properties required for carriers used in non-viral gene delivery.
Chloroquine affects the release of exogenous DNA accumulated in endosomes as well as its stability and expression.
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Hyperbranched polymers conjugated to a peptide-aptamer were prepared using a combination of RAFT polymerisation and click chemistry for targeting tumour cells in vivo. The polymers showed enhanced ...cell-uptake in vitro (compared to unconjugated polymer) while excellent specificity for solid tumours was observed in vivo using a mouse model of melanoma.
For tidal-stream energy to become a competitive renewable energy source, clustering multiple turbines into arrays is paramount. Array optimisation is thus critical for achieving maximum power ...performance and reducing cost of energy. However, ascertaining an optimal array layout is a complex problem, subject to specific site hydrodynamics and multiple inter-disciplinary constraints. In this work, we present a novel optimisation approach that combines an analytical-based wake model,
FLORIS
, with an ocean model,
Thetis
. The approach is demonstrated through applications of increasing complexity. By utilising the method of analytical wake superposition, the addition or alteration of turbine position does not require re-calculation of the entire flow field, thus allowing the use of simple heuristic techniques to perform optimisation at a fraction of the computational cost of more sophisticated methods. Using a custom condition-based placement algorithm, this methodology is applied to the Pentland Firth for arrays with turbines of
3.05
m
/
s
rated speed, demonstrating practical implications whilst considering the temporal variability of the tide. For a 24-turbine array case, micro-siting using this technique delivered an array 15.8% more productive on average than a staggered layout, despite flow speeds regularly exceeding the rated value. Performance was evaluated through assessment of the optimised layout within the ocean model that treats turbines through a discrete turbine representation. Used iteratively, this methodology could deliver improved array configurations in a manner that accounts for local hydrodynamic effects.
Introduction
There is an emerging need for the offshore renewable industry to have their own bespoke design guidelines because the associated projects and offshore facilities differ in fundamental ...ways to oil and gas facilities. Offshore renewable energy (ORE) facilities have already surpassed the numbers of installed facilities in the oil and gas industry by an order of magnitude and demand is forecast to continue growing exponentially. In addition ORE facilities often have different response characteristics and limit states or failure modes as well as profoundly different risk and consequence profiles given they are generally uncrewed and do not contain explosive hydrocarbon fluids which might be released into the environment. Therefore, the purpose of this paper is to advocate for licensing bodies and regulators (such as the various national PEL 114 committees) to challenge the process of automatic adoption of oil and gas design processes, while pushing for offshore renewables to be treated differently, when appropriate, with more relevant and applicable guidance.
Methods
To support this argument we present new bespoke design guidance developed for subsea cables based on specific modes of cable behaviour, which often differ from pipelines. We also show worked examples from recent project experience. The results from on-bottom stability analyses of a set of cables are compared between conventional oil and gas guidance following DNV-RP-F109 versus the stability using cable-optimised approaches.
Results
The outcomes from the ‘conventional’ oil and gas results are not simply biased compared to cable-optimised design methods, with a trend of being either conservative or unconservative. Instead, the results of the two methods are very poorly correlated. This shows that the oil and gas approach isn't simply biased when applied to cables, but is instead unreliable because it doesn't capture the underlying failure conditions. These analytical comparisons are supported by field observation - the ocean doesn't lie, and makes short work of any anthropogenic structures which are designed with inadequate appreciation of the real world conditions.
Discussion
To support the rapid growth of ORE, we should therefore actively pursue opportunities to rewrite the design rules and standards, so that they better support the specific requirements of ORE infrastructure, rather than legacy oil and gas structures. With more appropriate design practices, we can accelerate the roll out of ORE to meet net zero, and mitigate the climate crisis.
Lipophilic carriers have shown great potential in improving the delivery of gene therapeutics. We have synthesized positively charged peptide-based carriers including lipoamino acids. The carriers ...were shown to interact with DNA by performing isothermal titration calorimetry and particle size and zeta potential experiments. An exothermic reaction resulted from the titration of carrier into DNA. The particle sizes of the carrier/DNA complexes varied over the different charge ratios from 200–800
nm. The zeta potential was negative at a low charge ratio but positive when the amount of carrier was increased. The utilisation of lipophilic carriers is a promising approach to improve the bioavailability of gene delivery.
The synthesis and physico-chemical examination of lipophilic non-viral gene delivery carriers is reported.
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•Temporal characterisation of wave and tidal resource availability for Great Britain.•Ten metrics used to explore temporal characterisation and supply-demand matching.•Generation profiles with marine ...energy consistently outperform those without.•Correlation with load is not a suitable metric to establish supply-demand alignment.•Detailed discussion of potential GB power system benefits from marine energy.
Wave and tidal energy have the potential to provide benefits to power systems with high proportions of stochastic renewable generation. This is particularly applicable in combination with wind and solar photovoltaics, as the offsetting of these renewable resources results in more reliable renewable generation. This study utilises ten metrics to quantify the temporal complementarity and supply-demand balancing requirements of the energy mix in Great Britain, to investigate the potential magnitude of these system benefits. Wave and tidal generation profiles are created using historical resource data and hydrodynamic models. The results show that the inclusion of wave and tidal generation creates a renewable energy mix which is more available under multiple conditions: throughout a year of operation; at times of peak demand; for multiple consecutive hourly time periods; and at times when wind and solar generation are not available. Three regional case studies also show that the inclusion of marine energy allows for improved regional supply-demand matching, reducing instances of energy shortage and excess and potentially relieving transmission congestion at particularly constrained locations within GB. Finally, the implications of these findings are discussed in terms of GB wholesale market operation, system balancing and system security.
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