Adam Hawkes

Fuel cells for micro-combined heat and power generation

Micro-combined heat and power (CHP) holds great potential for lowering energy cost and CO2 emissions in the residential housing sector. Of the various micro-CHP technologies, fuel cells, and in particular solid oxide fuel cells, show great promise due to their high electrical efficiency and resulting low heat-to-power ratio that is better suited to residential applications. However, fuel cells are still under development and the capital cost of units available today remains high. This paper looks at the technological aspects and operating modes of fuel cells relevant to micro-CHP as well as examining the state of commercial development, life cycle issues and the techno-economics of fuel cells for micro-CHP at the residential scale.

A review of domestic heat pumps

Heat pumps are a promising technology for heating (and cooling) domestic buildings that provide exceptionally high efficiencies compared with fossil fuel combustion. There are in the region of a billion heat pumps in use world-wide, but despite their maturity they are a relatively new technology to many regions. This article gives an overview of the state-of-the-art technologies and the practical issues faced when installing and operating them. It focuses on the performance obtained in real-world operation, surveying the published efficiency figures for hundreds of air source and ground source heat pumps (ASHP and GSHP), and presenting a method to relate these to results from recent UK and German field trials. It also covers commercial aspects of the technologies, the typical savings in primary energy usage, carbon dioxide emissions abatement that can be realised, and wider implications of their uptake.

Role of fuel cell based micro-cogeneration in low carbon heating

Micro-cogeneration, otherwise known as micro-combined heat and power (micro-CHP), is an emerging class of technologies designed to replace conventional home space heating and hot water systems. In addition to meeting thermal needs, they also provide electricity for on-site consumption or sale. The prime mover in a micro-CHP system can be based on a number of technologies: Stirling engine, internal combustion engine, Rankine cycle, or fuel cells. This article is concerned with the technology, techno-economics, and environmental credentials of the fuel cell-based systems, notably polymer electrolyte fuel cells and solid oxide fuel cells. It is demonstrated that these systems have a distinct advantage over their engine-based counterparts in that they have a low heat-to-power ratio, allowing them to operate more consistently over the year and thus achieve higher utilization. It is also shown that they could form an important part of a future portfolio of low carbon heating technologies. The challenge now lies with fuel cell developers and integrators to demonstrate their durability and to reduce capital costs.

Infrastructure, Investment and the Low Carbon Transition

Infrastructures have a key role to play in the delivery of energy services in a sustainable and reliable manner. Infrastructure investment however presents a challenge because distributing the costs and benefits of investing in and maintaining a reliable energy system is not straightforward. There are a number of important issues which need to be addressed such as the allocation of risk between investors and energy customers and the degree to which today’s customers should pay for an energy system which will be enjoyed by customers long into the future. A number of solutions have been adopted throughout the years; for example, during the period of nationalised infrastructures in the UK, costs and risks were socialised as part of centrally planned public investment programmes. The subsequent restructuring of the energy sector saw private investors being exposed to market signals and the associated risk of making bad investments.

Feasibility of domestic micro combined heat and power units with Real Time Pricing

Within the context of recent interest in ‘Smart Grids’, this paper considers the possibility that domestic consumers could participate in demand side management. Price is one of the main concerns for domestic consumers, and hence Real Time Pricing (RTP) can have an influence on consumers with dispatchable generation such as micro combine heat and power (micro-CHP). These systems can reduce the annual operating costs for consumers and simultaneously improve the load profile on the network. This paper employs a cost minimization unit-commitment approach to investigate the Pay Back Times for micro-CHP under RTP and results show that they are heavily dependent on capital costs of the systems. Therefore, such investment is presently only feasible when incentives such as capital grants exist. The total carbon dioxide emissions and load profile both see improvements when micro-CHPs are present. Furthermore, with the RTP scenario, on/off switching of many micro-CHP units causes the aggregate load profile to behave stochastically as the prices change and this is especially true during summer months. Therefore, the methodology for pricing units of energy needs to be thought through thoroughly before implementing RTP in the residential sector.

Techno-economic assessment of small and micro combined heat and power (CHP) systems

Abstract: This chapter introduces the economics of small-scale CHP systems. Beginning with a review of how decentralised energy resources can achieve economic value, it then discusses the sometimes ill-defined concept of techno-economics, and the variety of modelling techniques that underpin it. An optimisation method that pinpoints the key characteristics of commercially successful CHP is presented and applied to the case of micro-CHP in the UK, demonstrating that the heat-to-power ratio prime mover is the key driver of economic and environmental performance. Finally, the emerging tension between CHP and heat pumps is discussed in relation to future stringent emissions reduction targets.

Fuel cell systems for small and micro combined heat and power (CHP) applications

Fuel cells are electrochemical energy conversion devices that turn chemical fuel directly into electrical power as well as generating heat. They operate at high efficiency and can be applied across a wide range of applications. Micro-combined heat and power (CHP) is one area in which fuel cells are expected to have a particularly significant impact with the potential for lowering energy cost and CO2 emissions in the residential housing sector. This chapter looks at the technological aspects of fuel cells applied to micro- and small-scale CHP applications as well as examining the state of commercial development and future trends.

An optimization method to estimate the SOFC market in waste water treatment

Abstract Wastewater treatment plants (WWTP) are one of the most energy intensive public utilities. The valorization of the biogas produced from the sludge in combined heat and power (CHP) systems allows important energy and emissions reduction, particularly if highly efficient engines, like solid-oxide fuel cells (SOFCs) are used. This paper proposes a two-stage stochastic optimization approach to assess the market potential for SOFCs in WWTPs in Europe. Despite the biogas availability is a challenge to guarantee continuity of operation, the results show that the WWTP is a promising market to pave the way for SOFC cost reduction and further technological learning.

The role of CCS and biomass-based processes in the refinery sector for different carbon scenarios

Abstract This paper studies technological pathways in the refinery sector, such as fuel switching, carbon capture and storage (CCS), energy efficiency as well as retrofit decisions (i.e. upgrading, scaling-up, and equipment modernisation) with the aim of decarbonisation. A global refinery outlook is presented for a 2.5 °C and 2 °C climate target scenario from 2010 through to 2050. The results highlight that a full portfolio of technologies (non-conventional processes, gas-/coal- based, with/without CCS, and biomass- based process) is necessary. Among the conventional refineries, only the most efficient ones or those investing in CCS to increase competitiveness and reducing emissions, can stay in the market.

Decarbonisation of the Industrial Sector by means of Fuel Switching, Electrification and CCS

Abstract The industrial sector will have to undergo major changes in order to reduce its emissions with the goal of climate change mitigation. In this context, the iron and steel subsector accounts for the highest CO 2 emissions share. This work uses a simulation model of the global energy system and quantifies the impacts of different measures for CO 2 reduction (such as fuel switching, electrification and Carbon Capture and Storage - CCS) on investment and operation decisions. The reported scenarios consider the implementation of a CO 2 price as a policy instrument to decarbonise the industrial sector. The selected case study covers steel production in the USA up to the year 2050. The results show that single measures such as fuel switching, electrification and CCS adoption alone have a limited impact on the decarbonisation of the iron and steel sector and should be rather implemented all together in an integrated approach towards climate change mitigation.