Clara F. Heuberger

Quantifying the value of CCS for the future electricity system

Many studies have quantified the cost of Carbon Capture and Storage (CCS) power plants, but relatively few discuss or appreciate the unique value this technology provides to the electricity system. CCS is routinely identified as a key factor in least-cost transitions to a low-carbon electricity system in 2050, one with significant value by providing dispatchable and low-carbon electricity. This paper investigates production, demand and stability characteristics of the current and future electricity system. We analyse the Carbon Intensity (CI) of electricity systems composed of unabated thermal (coal and gas), abated (CCS), and wind power plants for different levels of wind availability with a view to quantifying the value to the system of different generation mixes. As a thought experiment we consider the supply side of a UK-sized electricity system and compare the effect of combining wind and CCS capacity with unabated thermal power plants. The resulting capacity mix, system cost and CI are used to highlight the importance of differentiating between intermittent and firm low-carbon power generators. We observe that, in the absence of energy storage or demand side management, the deployment of intermittent renewable capacity cannot significantly displace unabated thermal power, and consequently can achieve only moderate reductions in overall CI. A system deploying sufficient wind capacity to meet peak demand can reduce CI from 0.78 tCO2/MWh, a level according to unabated fossil power generation, to 0.38 tCO2/MWh. The deployment of CCS power plants displaces unabated thermal plants, and whilst it is more costly than unabated thermal plus wind, this system can achieve an overall CI of 0.1 tCO2/MWh. The need to evaluate CCS using a systemic perspective in order to appreciate its unique value is a core conclusion of this study.

A systems approach to quantifying the value of power generation and energy storage technologies in future electricity networks

Abstract A new approach is required to determine a technologys value to the power systems of the 21st century. Conventional cost-based metrics are incapable of accounting for the indirect system costs associated with intermittent electricity generation, in addition to environmental and security constraints. In this work, we formalise a new concept for power generation and storage technology valuation which explicitly accounts for system conditions, integration challenges, and the level of technology penetration. The centrepiece of the system value (SV) concept is a whole electricity systems model on a national scale, which simultaneously determines the ideal power system design and unit-wise operational strategy. It brings typical Process Systems Engineering thinking into the analysis of power systems. The model formulation is a mixed-integer linear optimisation and can be understood as hybrid between a generation expansion and a unit commitment model. We present an analysis of the future UK electricity system and investigate the SV of carbon capture and storage equipped power plants (CCS), onshore wind power plants, and grid-level energy storage capacity. We show how the availability of different low-carbon technologies impact the optimal capacity mix and generation patterns. We find that the SV in the year 2035 of grid-level energy storage is an order of magnitude greater than that of CCS and wind power plants. However, CCS and wind capacity provide a more consistent value to the system as their level of deployment increases. Ultimately, the incremental system value of a power technology is a function of the prevalent system design and constraints.

Levelised Value of Electricity - A Systemic Approach to Technology Valuation

Abstract The mitigation of climate change requires a near total decarbonisation of the power generation sector by 2050. Decisions on the amount of generating capacity, the types of technologies, and their operation are crucial to achieving emission targets. As power plants operate in an interconnected system, their evaluation should be based on their contribution to overall system performance as opposed to their individual costs when operating in isolation. In this contribution, we present a methodological approach for deriving the Levelised Value of Electricity (LVOE) as a new metric determining the value of a technology to the electricity system. The methodology is based on a mixed-integer linear program (MILP) which simultaneously optimises the electricity system design and operation. It considers both security of supply and environmental aspects and presents the technology value as a function of the prevalent system conditions. An illustrative study on the LVOE of Carbon Capture and Storage (CCS) power plants reveals how the economic deployment of CCS could reduce total system cost in the future UK energy system.

Optimal Scheduling of Air Separation with Cryogenic Energy Storage

Abstract The idea of cryogenic energy storage (CES), which is to store energy in the form of liquefied gas, has gained increased interest in recent years. Although CES at an industrial scale is a relatively new approach, the technology used for CES is well-known and essentially part of any cryogenic air separation unit (ASU). In this work, we assess the operational benefits of adding CES to an existing air separation plant. Three potential new opportunities are investigated: (1) increasing the plant’s flexibility for load shifting, (2) storing purchased energy and selling it back to the market during higher-price periods, (3) creating additional revenue by providing operating reserve capacity. We develop a mixed-integer linear programming (MILP) scheduling model for an ASU- CES plant and apply a robust optimization approach to model the uncertainty in reserve demand. Results from an industrial case study show that the amount of wasted products can be considerably reduced and significant cost savings can be achieved by utilizing the CES.

Closing the carbon cycle to maximise climate change mitigation: power-to-methanol vs. power-to-direct air capture

It is broadly recognised that CO2 capture and storage (CCS) and associated negative emissions technologies (NETs) are vital to meeting the Paris agreement target. The hitherto failure to deploy CCS on the required scale has led to the search for options to improve its economic return. CO2 capture and utilisation (CCU) has been proposed as an opportunity to generate value from waste CO2 emissions and improve the economic viability of CCS, with the suggestion of using curtailed renewable energy as a core component of this strategy. This study sets out to quantify (a) the amount of curtailed renewable energy that is likely to be available in the coming decades, (b) the amount of fossil CO2 emissions which can be avoided by using this curtailed energy to convert CO2 to methanol for use as a transport fuel – power-to-fuel, with the counterfactual of using that curtailed energy to directly remove CO2 from the atmosphere via direct air capture (DAC) and subsequent underground storage, power-to-DAC. In 2015, the UK curtailed 1277 GWh of renewable power, or 1.5% of total renewable power generated. Our analysis shows that the level of curtailed energy is unlikely to increase beyond 2.5% until renewable power accounts for more than 50% of total installed capacity. This is unlikely to be the case in the UK before 2035. It was found that: (1) power-to-DAC could achieve 0.23–0.67 tCO2 avoided MWh−1 of curtailed power, and (2) power-to-Fuel could achieve 0.13 tCO2 avoided MWh−1. The power-to-fuel concept was estimated to cost

Power Generation Expansion Considering Endogenous Technology Cost Learning

209 tCO2 avoided−1 in addition to requiring an additional

Air separation with cryogenic energy storage: Optimal scheduling considering electric energy and reserve markets

430–660 tCO2 avoided−1 to finally close the carbon cycle by air capture. The power-to-DAC concept was found to cost only the

Opening the black box of energy modelling: Strategies and lessons learned

430–660 tCO2 avoided−1 for air capture. For power-to-fuel to become profitable, hydrogen prices would need to be less than or equal to

Power capacity expansion planning considering endogenous technology cost learning

1635 tH2−1 or methanol prices must increase to

Real-World Challenges with a Rapid Transition to 100% Renewable Power Systems

960 tMeOH−1. Absent this change in H2 price or methanol value, a subsidy of approximately