Like any new technology, Heat Pumps have their detractors. In that sense they are a bit like Twitter – controversial but incredibly useful.

For those of you who don’t use Twitter, you probably only hear negative things about the platform. But how else would you stumble across the work of Robert Howarth?

Who is Robert Howarth? He is an eminent Professor of Ecology and Environmental Biology at Cornell University and holds a PhD from MIT – both institutions amongst the top in the World. His webpage is here: Robert Warren Howarth | Department of Ecology and Evolutionary Biology (cornell.edu)

In the research paper mentioned in the Twitter feed above Professor Howarth seeks to understand, using all the available data, which method of heating water yields the lowest amount of Green House Gas emissions. In the US, 18% of the energy delivered to households is used to heat water.

Naturally there is a lot of complexity within the research paper, and it makes some important (worst case) assumptions. For instance, it assumes that all of the electricity used in the heat pump was generated by coal or gas. In the UK, a very substantial proportion of our electricity now comes from wind, solar, hydro or nuclear. It never comes solely from coal or gas.

The central finding of the paper is this: “Methane and Carbon Dioxide emissions associated with heating water with a storage natural gas water heater (which is the most common way of heating water in the U.S.) was greater than that with a heat pump water heater powered by electricity from coal across all time scales considered in this study (up to 100 years)”.

In other words, the normal way to heat water using gas is worse for green house gas emissions that a heat pump, even if you assume that all the electricity for the heat pump comes from the worst polluting fossil fuel of all (coal).

Furthermore, Shale Gas is known to be much worse for the environment than regular natural gas. So another important observation that Howarth makes is that heating water using Shale Gas is actually 5-6 times worse for Green House Gas emissions than using Heat Pumps.

Howarth concludes:

“Natural gas is often portrayed as a “bridge fuel,” with the implication that it is a preferable energy source over other carbon-based fossil fuels resulting in a less adverse impact on the climate, desirable to be used until carbon-free technologies are mature and in place

The analysis presented here provides counterarguments to this idea in two different aspects: that

(1) using natural gas-based technologies can result in even higher emissions of GHGs than using coal-based technologies, and that    

(2) technologies that can support carbon-free sources of energy already exist in an                         economically viable way.

The electricity powering the heat pump water heaters can be generated from carbon-free energy sources such as wind, solar, hydropower, and geothermal sources that have little or no emissions directly related to electricity production; yet, even when powered by electricity from coal and natural gas, total GHG emissions from generating domestic hot water with heat pumps is less than directly using natural gas. Therefore, currently available modern technologies like the heat pump water heater are in fact a true bridge to the clean energy environment.”

So What?

Well, it is a common criticism of Heat Pumps that if the electricity they use isn’t green, then the heat pump itself isn’t green.

Howarth’s paper completely debunks this criticism.

The unfortunate thing is that Howarth’s paper was published in Jan 2016, and yet these kinds of criticisms are still common.

What about cost?

Most consumers are primarily motivated by cost. In particular, the installation cost and the running cost of a Heat Pump.

At Brimstone Energy, we would never advocate ripping out a serviceable gas boiler and replacing it with a Heat Pump.

Financially it makes sense to do the following:

1.            Run your current system to its optimal efficiency.

2.            Service your current system annually and retain it for as long as is economically viable. Your boiler should have a life span of at least 20 years.

3.            Get “Heat Pump Ready.” This will probably mean replacing some radiators and improving the insulation of your property. This will provide immediate benefits as well as making the installation of a heat pump a simpler (and cheaper) affair in the future.

In terms of running costs, this is changing all the time. The biggest factor is what price are you buying your electricity at versus your natural gas.

As at May 2023, you’ll be buying Natural Gas at about 10.5 pence per kWh. With Octopus Flux, the Heat Pump tariff from Octopus Energy with a double dip price drop, you’ll pay about 20 pence per kWh for 6 hours a day.

Since your heat pump will be at least 3 times more efficient that your gas boiler, you can quickly see that in this scenario, the heat pump is actually cheaper to run than the boiler.

What’s next?

The starting point for all domestic Energy Efficiency measures is a Heat Loss Survey of your home since the bulk of domestic energy consumption relates to heating, both space heating and water heating.

Brimstone Energy will give you impartial advice on how best to improve the energy efficiency of your home, and issue a step by step guide bespoke to your property.

Brimstone Energy – For all your Home Energy Needs