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Topic Review: Heating in a low-carbon future

renewables

11 Jan 2019

SCI Energy group’s first major conference, Heating in a Low-Carbon Future, will be held at SCI HQ on 28 February 2019. Here, members of the group talk about the changes needed for the UK to embrace a low-carbon future.
Brian Allin and Peter Reineck, SCI Energy group

Affordable, sustainable energy is fundamental to the UK’s prosperity, but new technologies are needed to achieve an 80% reduction in CO2 emissions from 1990 levels by 2050, while meeting energy demand and keeping energy costs competitive. In 2015, 21% of the total 489m tonnes net of CO₂ emissions from the UK energy system came from heating buildings and 17% from heating homes.

Reducing CO₂ emissions from the way we heat our homes is key to hitting these targets. Converting most of the UK’s domestic and light commercial properties to low-carbon heating will require innovative, adaptive technologies, switching a large part of the load from natural gas and oil to low-carbon electricity, while mains power will increasingly be used to charge vehicles.

Supply networks will need to be more robust but recognising that the scope for enlarging them is limited. Forms of heating that do not increase power consumption, such as district heating or adding hydrogen to the gas grid, will be part of the mix. Investment and running costs will also need to be controlled so that it is affordable.

SCI’s Energy group is developing new perspectives on the energy trilemma – reliability, affordability and sustainability – by modelling alternative scenarios for the UK energy system that focus on optimal use of available and emerging technologies. The modelling work was conducted by the Energy Technologies Institute using its ESME energy model. The outputs and conclusions will provide an objective, evidence-based view on the role of science and innovation in the UK energy sector for use in government consultations, and to inform regulatory and market incentives and investments.

 

The Low Carbon Economy. Video: UK Trade & Investment

Interim findings from our modelling suggest smart control systems as the most cost-effective choice for home owners to save energy and hence reduce CO₂ emissions from heating their homes, while also reducing their bills. A reduction in CO₂ emissions from home heating in the range of 30% could be obtained from energy efficiency measures combining smart control systems with upgrading insulation, resulting in improved comfort and a reduction in natural gas consumption. Low-carbon routes to heating, such as heat pumps, provide attractive choices to reduce emissions further.

Energy efficiency measures must be considered as a primary step to avoid excessive heating demand, minimising the requirements of electrical and heating networks. The upgrade of insulation and inclusion of renewable energy requirements in building regulations has improved new-build and major refurbishments. Previous initiatives to retrofit loft insulation and cavity wall fills to existing homes have been successful due to the quick payback – based in part on subsidies – and improvement in comfort, as well as not being greatly intrusive.

However, these initiatives only raised energy efficiency to a fraction of the level required by regulations. This leaves a large proportion of existing dwellings with less than adequate energy efficiency. Many of these homes have been seen as difficult to improve because of the perceived adverse impact of insulation materials on the property, whether applied inside or externally.

New materials like aerogels and vacuum insulated panels applied to the inside of external walls, as well as potential innovations in cellular polymer insulation, offer vastly improved insulation, comfort and reduction in dampness without sacrificing significant space. For example, a thickness of 16mm of aerogel with a support/decoration medium like magnesia (MgO) board can achieve up to a 70% reduction in heat loss, compared with brick, which still constitutes a sizable portion of UK built stock construction.

Smart control systems are a low-cost way to challenge home owners and tenants to save energy, while improving efficiency and comfort by controlling the temperature of different parts of their homes at all times of the day and night using their smartphones.

smart energy at home

Smart energy systems could save consumers considerable amounts of money.

Heat pumps offer a large improvement in the efficiency of electric heating based on the ratio of heat output to the electrical energy used (coefficient of performance), which can average three, thereby reducing the electrical energy required by around 35%. In terms of the electricity grid, this equates to 3kWh of energy from every kWh transmitted. 

Innovation in heat pump design can reduce the insurge current on start-up, which can be many times the running current, by idling the equipment when offload rather than stopping completely. Inverter motors can overcome an inherent inefficiency of electric motors by varying motor input frequency and voltage to control speed and torque.

Heat pumps come in various forms. Air recovery standalone heaters doubling as air conditioners in summer are particularly good where electricity provides heating. Air-source water heating units can replace gas boilers providing hot water and heating for water-based radiators or underfloor systems – the latter can operate more efficiently due to the lower running temperatures. There are also ground-source systems.

Coupling heat pumps with thermal solar panels, photovoltaics, local microgrids, other renewables or energy storage, enhances energy efficiency and lowers running costs once initial capital outlay has been recovered. These systems can also help decouple energy requirements for heating from the electricity grid supply, particularly at times of high demand, thereby improving the grid’s robustness. Microgrids can also reduce the net cost of solar panels by allowing surplus electricity to be sold to neighbours, which can be facilitated, perhaps, by blockchain technology.

Two other methods – hydrogen and district heating – deliver energy to homes without increasing the load on the power grid but require significant investment in infrastructure. Adding hydrogen from gasification plants with CO₂ capture to the gas grid could progressively decarbonise the gas supply without disrupting how we heat our homes or cook. District heating uses a central CHP plant firing low-carbon or biorenewable fuel, such as biomass or waste, to generate steam for transmission to buildings and condensate return in insulated pipes.

Legislation requiring developers to incorporate zero-carbon construction and future proofing may be necessary, while awareness and training in zero-carbon design, construction and maintenance needs to be encouraged urgently.

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