Cut speed to lower emissions
It is good that HS2 has set out its plan to achieve “net zero”, but I cannot help thinking that they have missed a trick to reduce its carbon footprint further by operating at 200km/h instead of the 360km/h it is being built for.
It is estimated that the traction power requirement to run each HS2 train at 360km/h is a little over 13MW, whereas the typical power requirement to run at 200km/h is 6MW. That is a saving of over 50% in traction power per train.
There is no reason why HS2 cannot operate at 200km/h, which is the speed most other mainline services run. The current restriction on improved journey times is one of capacity of the railway network. The new dedicated railway will create considerably more capacity and will enable trains to run unimpeded by slow running, stopping or commuter trains.
Even at 200km/h, a new dedicated railway will enable any train to run at significantly improved journey times, competitive against air and road travel.
The Oakervee Review of HS2 does conclude that “the primary need is for capacity; speed, although an important factor in economic benefits, should not be in and of itself the primary driver of decision making”. That said, no one to my knowledge has ever questioned the speed at which HS2 will operate.
With the need to reduce emissions, surely it is now time to ask that question?
Rob Tidbury, Bristol
Build a robust supply chain
Whilst it’s great to see heat getting a mention in the magazine, it is after all 40% of our carbon footprint and needs much more attention.
There is a UK heat-pump manufacturing base, and we are driving innovation. Our innovation focus at Clade is on the integration of heat pumps with the wider energy system via smart connections and grid flexibility. Achieving the highest efficiency, at the lowest cost of energy, is of the highest importance. Innovation in data and continuous improvement engineering will enable us to succeed.
Heat pumps and their sister technology refrigerators have been with us for a long time and “new” types are rare. The high-temperature heat pump mentioned in your article is a CO2 heat pump. This is not new; the use of CO2 as a refrigerant dates from 1850. The optimisation of CO2 for heat pumps and the engineering to contain the higher pressures and temperatures is coming over from refrigeration, led by companies like Clade.
The biggest issue affecting the sector is the supply of materials and component parts. Not only are there raw material and semiconductor shortages but the global heat-pump market is expanding at an exponential rate.
The UK government’s expectation is that cost reductions will come about in a similar manner to the cost reduction of solar photovoltaics, but this is different. Refrigeration, chill and air-conditioning share the same well-established supply chain which has already been subject to value engineering and competitive pricing for many decades.
The UK’s policy focus should shift from price reduction to building a robust supply chain that can deliver 40% of the country’s carbon reduction commitment using existing and scaleable technology. We welcome the £30m recently announced to support heat-pump manufacturing and supply chain and hope it is the start of this transition.
Tim Rook, Chief Markets Officer, Clade, Bristol
Celebrate engineering’s long history
A recent article is headed “Sir Charles Parsons, inventor of the steam turbine”. A more appropriate title would be “perfector of the steam turbine”.
A sketch showing the concept of a reaction steam turbine (the type Parsons produced) was made by the Greek Hero of Alexandria in 200 BC. In 1629, Giovanni Branca published a gazette of machinery and among the items he depicted was the first description of what is now known as an impulse steam turbine.
Of course, at the time, the technology to produce either invention did not exist. Parsons was able to use his engineering background and evolved technology to perfect the ideas that had existed for many hundreds of years.
Dr Terry Noble, Deeping St James, Lincolnshire
Get to grips with the future factory at Advanced Manufacturing (18-22 July), part of the Engineering Futures webinar series. Register for FREE today.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.