Pages of books on a wall

Letters to the editor: volume 16, issue 12

Image credit: Patrick Tomasso/Unsplash

In the January 2022 issue of E&T, readers discuss the fallout from the COP26 UN Climate Change Conference in Glasgow.

Climate challenge is too urgent to ignore hydrogen

The main objective to have emerged from the recent COP26 United Nations climate change conference in Glasgow is to ensure that global temperature rise is limited to 1.5°C above pre-industrial levels by 2050. The temperature is already 1.1°C above and we see disastrous floods, droughts, fires, ice-melts in polar regions, disappearing permafrosts and immensely powerful storms. So at 1.5°C all these effects will be increased – a frightening prospect.

Although some countries have made promises to reduce coal extraction, burning methane and deforesting by 2030, they have generally been quiet about oil extraction. It is so urgent that fossil fuels are left in the ground. Hot and sunny countries like Saudi Arabia and India should surely be producing solar electricity and thereby supplying this and hydrogen (produced by electrolysis) to the rest of the world for transport etc, and for domestic steel production. Hydrogen could be exported by pipeline or bottled. Its use should be considered for domestic boilers using existing pipelines, and as bottled gas for transport. Apart from using fuel cells to convert hydrogen to electricity for transport uses, it could be used to power internal combustion engines directly.

No mention is made of world population, yet the enormous growth in the last 100 years or so has been the main cause of the climate problems. In the same period the forest/wilderness cover of the Earth’s surface has reduced from 66 per cent to 35 per cent. More people needing more food and shelter has meant more fuel, less forest cover and so on. It is my view that efforts need to be made to publicise the importance of limiting population growth.

Harry M Rosenbaum MIET
By email

Don’t write off gas too soon

A future balance between nuclear and hydrogen is clearly a potentially viable route to net-zero carbon dioxide. Assuming – optimistically – that 25GW of nuclear power is available by 2030, then solar and wind power capacity will need to supply electricity and release hydrogen from water using electrolysis and to store the gas.

Hydrogen gas turbine generators could then carry much of the grid system load variation – including that of new electric vehicle battery chargers and heat pumps – when there is little wind or sun. That would require over five times the total solar and wind capacity currently planned, to which must be added the hydrogen needs of transport and industry. National Grid estimates that decarbonisation of the Grid alone will cost £3tn, around £100,000 per household.

It must be clear that this is not going to happen by 2030 and that we will have to keep burning conventional gas for some time to come, with or without carbon capture and storage. King Canute could not buck the laws of physics and neither can all of the hot air released by the recent COP meeting.

Developing carbon capture technology and giving it to China, with its 30 per cent of human global emissions, would have a far greater impact, than nibbling away at the UK’s 1 per cent. We could then proceed without a massive increase in fuel poverty – caused by penalising fossil fuels – before alternatives are available.

Roger J Arthur MIET
By email

January 2022 Letters Section Cartoon

Image credit: E&T

Hydrogen engines beat impractical batteries

Electricity generation will be key to decarbonisation, but only if it’s green and comes from renewables or nuclear, which may be decades away. Tesla introduced mass electric cars and governments leapt at what they thought to be a good means to reducing emissions. But is low-density energy storage really such a green solution for road vehicles? Did governments evaluate the long-term environmental effects of various technologies before making the leap of faith? In several decades’ time, will battery power become impracticable?

A number of questions arise. Does planet Earth have sufficient lithium, nickel and cobalt to make batteries? As supplies dwindle their cost is likely to rise. Countries controlling their supply could prioritise their own battery manufacture, to the detriment of others. So is long-term supply politically secure for, say, cobalt from Chinese-owned mines in the Democratic Republic of Congo? And will electric cars be practicable world-wide? Will there be sufficient electrical generation to enable this?

Going electric sounds ‘green’. It may be in the locality of the car, but neither running electric cars nor battery manufacture is emission-free. In addition, electric cars are far heavier, leading to increased urban particulates from their tyres. To say nothing of their cost, which currently is beyond the means of many buyers.

A greener and better economic long-term UK aim would be to use internal combustion engines running on green hydrogen gas or zero-carbon fuel. This would have to wait for a hydrogen grid and large-scale zero-carbon fuel production. But the long-term result would be less expensive for buyers, better for the UK balance of payments, more sustainable, secure and environmentally friendly.

Hydrogen engine technology is mature, having been first developed in the 1920s. Demonstrator cars appeared in the 1970s. BMW made a small batch in 2007 and unsuccessfully tried to persuade the German government to go that way. Our diesel rail locos, construction plant and some HGVs may be planning to use hydrogen-powered IC engines because batteries may be impracticable. If for rail, why not also for cars?

In the UK, both Cummins (with government backing) and JCB are working on hydrogen internal combustion engines. They are a little more costly than a diesel, unlike batteries or fuel cells, and almost as efficient. For most of their operating range their exhaust is only steam. They do emit a small amount of NOx but only near full power and easily removed by a catalyst.

The UK could be self-sufficient with hydrogen electrolysed by nuclear or wind and solar green electricity. So, might relying on batteries be a short-term phase? Might combustion engines stage a revival? Will the huge investment in battery manufacture and charging points in hindsight be seen as unwise policy? Long-term, would our renewable electricity generation be better used to produce hydrogen rather than power electric cars?

Colin Mynott

Stop sending energy down the drain

I read the November 2021 issue of E&T magazine, which focused largely on the COP26 conference, with interest. There were letters and articles galore about wind turbines, solar power, heat pumps, MHVR systems, insulation, power distribution and a plethora of other related subjects, but astoundingly, there was little or no mention of waste water heat recovery (WWHR) systems.

Water is an amazing compound that has the highest specific heat capacity of any liquid readily available for use by mankind. That’s why we use it to cool things down with (and fight fires) very effectively. It will absorb copious amounts of energy very quickly. Liquid ammonia has a slightly higher specific heat capacity but with a boiling point of -33.4°C is somewhat inconvenient to use, for obvious reasons.

Water, however, has the unique property of turning from a solid to a liquid, and subsequently from a liquid to a gas, in a range of only 100°C. We procure, store, transport, filter, treat and purify millions of tonnes a day of one of our planet’s most precious resources to an incredible degree, use mind-boggling amounts of energy to heat it up and then we simply pour it down the drains. It’s absolute stupidity!

I consider that as well as discovering and employing new methods of generating clean energy, we all need to use much less of it. The adoption of WWHR systems into mainstream domestic and commercial use would go a long way to achieving that end. Only two or three decades ago, the vast majority of domestic energy was used in heating houses. With the great amount of insulation that we now have in our homes, most of our domestic energy is now used in heating hot water, which we then pour down the drains. If every new house that was built had a WWHR system designed and built into it at the planning stage, the amount of energy required to heat domestic hot water could easily be more than halved. This would have a massive impact on the total energy consumption, but also on the cost to the consumer.

It’s a technology that is still very nascent, but research and development should go into making these systems readily available, affordable, easy to install by builders and plumbers, easy to maintain by the householder and they should be the norm, rather than the exception, on all houses.

I am currently in the process of building a large house on the west coast of Scotland, with five bathrooms. All of the waste water from the showers and baths goes into a separate drainage system that feeds into a 1,000-litre insulated tank. The water stratifies in temperature and a copper coil of pipe taking the cold water feed to the domestic hot water tank recovers the heat from the grey water. A swan-neck exit from the WWHR tank ensures that only cold water is pushed out to the foul drain to which it discharges. Naturally, a bypass valve is incorporated into the design to allow for cleaning and sluicing out of the tank on a periodic basis. The additional materials cost of the system installation amounted to only a few hundred pounds and the savings made on energy will pay for these additional install costs within a very short period of time.

Basic calculations have shown that more than 80 per cent of the energy put into the hot water is recovered by the use of this system. The proof of the pudding is in the eating, they say, and with total biomass fuel costs of under £10 per week, to heat a large 450m² six-bedroomed house and, more importantly, to provide all of the hot water required, via a log-gasification boiler, I consider that this pudding needs no sweetening! The fact is that I only ever put cold water down my drains.

Scandinavian countries have been leading the way with heat pump technology for decades. They’ve also been using WWHR systems for a long time. Even the energy-profligate North Americans have been incorporating WWHR into upstairs shower installations for many years. In the UK and much of the rest of the world, however, we are way behind.

We should be making WWHR technology more available, easier to install and maintain, cheaper to buy and, ultimately, mandatory in all new-build houses, offices and other commercial properties. It’s another important component in the big mix needed to achieve net-zero carbon emissions and the strategic planners shouldn’t neglect this important element. At present, it seems that most people are blind to it, but in the same way that heat pump technology has exploded onto the market recently, in ten years’ time, we’ll all be wondering why we weren’t properly doing WWHR decades ago.

Ivan Woolley

Write to E&T at We reserve the right to edit letters and to use submissions in any other format.

Sign up to the E&T News e-mail to get great stories like this delivered to your inbox every day.

Recent articles