One day many of us will have to do something even more radical: rip out our gas boilers. The government’s official advisers on climate change say almost all homes — 85% of which currently use gas — need low-carbon heating by 2050. The chancellor has proposed a ban on gas boilers in all new-build homes from 2025, but the far bigger challenge is how to wean 24m existing homes off their gas heating. So, if you need a new boiler, what are the greenest options. Electric heating it is still far more costly to run, at an average of 14p per kWh, as opposed to 4p for gas. That’s why current rules contradict the committee’s proposals: energy performance certificates (EPCs), which you need before you can let or sell your home, rate electric heating as much worse than gas combi boilers. In well-insulated homes that need little heating, electric boilers can be the most cost-effective replacement. They’re about the same price as the gas equivalent, but are less powerful. An electric combi boiler, which instantly heats mains water for taps and central heating, would suit a one-bedroom flat; for anything bigger, you’d need to add a cylinder and perhaps a second boiler. By reversing the process that cools a fridge, a heat pump extracts thermal energy from the air or ground and multiplies that to heat homes. It needs 1kWh of electricity to produce up to 2.5kWh of heat, so has less than half the emissions of a gas boiler for about the same running cost. Despite this, Britain fits only 20,000 heat pumps a year, compared with 240,000 in France. In order for every home to have one, UK electricity generation would have to treble, experts say. Heat pumps typically cost between £7,000 and £9,000; Mitsubishi Ecodan, Samsung and Daikin are the leading brands. The government’s renewable heat incentive (RHI) aims to pay you back the excess cost above that of a gas boiler in the space of seven years. Hydrogen is the most common chemical element and gives off only water vapour when burnt. It made up half of the “town gas” used in Britain until the 1970s, when it was replaced by natural gas from the North Sea. Now government-funded research is again seeking ways to pipe hydrogen to our homes. A full conversion would require boilers and cookers to be replaced. But one hydrogen boiler is already available that can be fitted without changing your hob or pipework: the Viessman Vitovalor. It uses a catalyst to split hydrogen off natural gas from the mains supply. It then burns this using “cold combustion” to produce electricity and heat — shaving £700-£900 off annual fuel bills for a three- to five-bedroom house, according to Patrick Wheeler.
Times 12th May 2019 read more »
THE Scottish Government is being urged to mirror the success of countries such as Denmark and reconsider its approach to the commissioning, design and implementation of district heating systems (DHS), or heat networks. A study published today by the “think and do tank” Common Weal suggests the work would be within the scope of currently devolved powers, along with the development of its favoured National Energy Company (NEC). The paper suggests the NEC would work with a Scottish Energy Development Agency (SEDA) and a public National Energy Service (NES) to maximise the benefits of investment in new DHS projects. In their study, Dr Keith Baker and Dr Ron Mould point to the success of Denmark in the development of successful and sustainable DHS and heat networks. They say evidence shows that using multi-technology approaches – particularly those combining large-scale solar thermal with sustainable biomass and inter-seasonal heat storage and recovery technologies – must become a central theme in the future development of DHS in Scotland. “However, sadly, such thinking currently appears to be completely beyond the Scottish’s Government,” they add. Mould told the Sunday National that DHS had great potential: “District heating has the potential to offer affordable low-carbon heating to homes and buildings. The Scottish Government has recognised this by putting policies in place with ambitious targets. However, district heating in Scotland has not always been successful. “This report is built on research on district heating and fuel poverty and pulls in expertise from a range of colleagues to highlight that there are experiences in Scotland, the UK and further afield, for example Denmark, from which we can learn.
The National 12th May 2019 read more »
WHEN it comes to shifting to a zero-carbon society, one of the big things that needs to be had is a public conversation around the way we heat and insulate our homes. It doesn’t sound glamorous. Talking about it doesn’t have the allure of the conversation about the latest breed of electric cars – but we need to do it. We need to talk boilers. A big question, then, is what does that mean for the gas boiler? Where do the millions of these across the country fit into a Scotland with a target of zero net carbon by 2045? Eighty per cent of our Scottish homes are heated by gas. The majority of new-builds are still being constructed with gas boilers. Yet methane gas, a fossil fuel, has no real place in a zero-carbon world. Its burning produces half the amount of carbon dioxide as coal and, when methane leaks, it is a powerful greenhouse gas itself. This boiler question seems particularly pertinent to me because my own boiler is old, on its last legs, and likely to be up for replacement soon. Yet, when I look around, It’s hard to see what the right replacement technology would be. One of the biggest questions is whether the solution lies in a decarbonised electrical supply or decarbonising the gas network. Currently, the most promising answer looks to be electricity, since the technologies are mostly already there – and the chief barrier, beyond cost, is the fact that many homes run on gas appliances which will have to be replaced. Electricity in Scotland is increasingly being generated by renewables, and by 2032 it’s predicted to be largely decarbonised. Nevertheless, many still see great potential in hydrogen, particularly given it could provide a solution to the fluctuating nature of renewables, and in a UKCC committee report published last autumn, the gas was touted as part of the answer. This is partly because, in the UK, we have one of the best gas grids in the world. Yu observes: “We’ve got a good gas network, why don’t we decarbonise the gas network? We could potentially switch to hydrogen, either as a percentage of the supply or entire supply after upgrading the networks.” The problem, however, with hydrogen is that there are still various technical challenges to surmount, as well as financial issues, in that appliances will have to be replaced by new hydrogen-friendly cookers and boilers, which are not yet available. There is also the issue of how hydrogen is produced. If it’s from methane, then the process involves the production of CO2 which then has to be captured, a process that is still in development and expensive. The other is by electrolysis from water, which is comparatively inefficient.
Herald 12th May 2019 read more »