It is a sad indictment of humankind that we always seem to feel the need for an adversarial approach to life, particularly when it includes the future of our planet.
We all recognise that there is an urgent need to develop a sustainable energy system, no longer dependent on finite fossil fuels. Given that, one might imagine that we would all be seeking the optimum solutions for each and every energy need, instead of insisting that our personally preferred technology should be used for every application.
It has been demonstrated repeatedly that the pursuit of single technology approaches is a misguided strategy; but maybe this time it is different? Maybe there is a single solution to decarbonising the energy system.
If we are trying to decarbonise our energy system, is electricity better than gas?
An absurd question…or is it?
For decades the nationalised gas and electricity industries in the UK (and elsewhere) squandered millions of taxpayers’ money in marketing their respective fuels. It went further. Both industries also spent vast sums to develop and demonstrate increasingly imaginative technologies aimed entirely at consuming more of those fuels.
And then came privatization and the arrival of energy companies who cared little about whether you consumed gas or electricity as long as it was their gas or electricity.
But now in 2020 we find ourselves again facing the same discussion, albeit within a somewhat different context. However, the physics has not changed, and the answer remains “it depends on what you want to do with it”.
Electricity and gas have very different characteristics and implicitly different applications. Few would argue that gas mantels are in any way superior to LED lighting in terms of efficiency, cost, light quality, safety, comfort, convenience…
Nor are there many who believe that electricity is the optimum solution for international shipping nor long haul aviation.
Electrons versus molecules
Rather than electricity versus gas, the argument is now presented as “electrons versus molecules”, predicated on the assumption that ultimately gas means hydrogen and green hydrogen at that. In other words, it is not electrification versus hydrogen, but direct electrification versus indirect electrification through hydrogen. There remain many applications for which molecules (gaseous hydrogen or liquid, hydrogen derivatives) will remain the most effective solution, including some industrial processes and heavy haulage. In this case we are less concerned with the efficiency of the process than in the practicalities of energy storage or the viability of the process itself.
And then there are applications best suited to direct electrification. They may not always be optimum from an energy system perspective, but have distinct merits in term of specific efficiency. The case of residential space heating from heat pumps being a case in point.
But there are overlaps between the characteristics of gas and electricity which might be able to deliver the best of both worlds. The obvious corollary of course is that it is also possible to get the worst of both worlds!
Delivering extreme scenarios
The recent Net Zero Coalition industry group study explored the implications of delivering three scenarios from the CCC proposals for decarbonisation of heat by 2050. These were an extreme electrification scenario, an extreme hydrogen scenario and a central pathway involving hybrid heat pumps.
All were challenging and all were expensive.
But the most surprising aspect was that even the extreme scenarios did not exclude the alternate extreme entirely. The “all-electric” future required significant amounts of green hydrogen production both to soak up the vast amounts of excess peak intermittent generation and to provide interseasonal storage.
Paradoxically, the more we strive for electrification, the more we depend on intermittent renewable generation and the more energy storage is required to balance the system.
There are those who use this factor as an argument against a system 100% dependent on renewables. They make the point that battery storage may be getting cheaper, but that it cannot conceivably provide the necessary level of storage required to balance the periods of low electricity production with those of high demand. And they are right, to a point.
Energy storage does not just mean batteries
But no-one is suggesting that batteries are the only, even dominant means of storage at a system level. Batteries may well provide intra-day storage allowing households to self-consume their own solar PV generation at night, but they are not going to help that same household meet their winter heating bills from their summer generation. For that we need longer duration, lower cost options. And that is where hydrogen fits in.
It is argued that converting high value renewable electricity to hydrogen and then back again to produce electricity when it is needed is not only inefficient, but also very expensive.
After all, hydrogen is always going to cost more than the electricity being used to produce it.
Or will it?
Can green hydrogen ever cost less than electricity?
Clearly, if we look at blue hydrogen (hydrogen produced from natural gas) then that is always going to cost more than natural gas. You first have to pay for the natural gas that goes into the blue hydrogen production, but then you also have to pay for the CCS and in the process lose a significant percentage of the energy content.
To some observers it seems that blue hydrogen is simply a cynical attempt by the fossil lobby to extend their future for as long as possible. Whether or not this is true, it does not necessarily mean we should abandon the existing gas distribution network; in the short term it allows for the distribution of lower carbon gas and in the longer term it should prove invaluable in supporting the hydrogen economy.
Even with green hydrogen there are those who see it as an excuse to do nothing about our dependence on gas boilers for heating. But again that does not invalidate the retention of valuable network assets which may one day be used to transport hydrogen to fuel cells rather than gas boilers; in both respects, retention of the gas network will ease the transition to a lower carbon energy system in the longer term.
The economic logic for blue hydrogen illustrates the point that as a transitional fuel we need to accept that energy costs for gas heated homes will rise, but is the same true in the longer term for homes supplied with green hydrogen?
In addition to the system flexibility that hydrogen can provide, maybe it can also compete on economic grounds. But surely the green hydrogen itself will cost more per kWh than the renewable electricity that went into making it. After all, production of green hydrogen requires renewable electricity plus expensive electrolysis equipment. Of course, it must cost more than the electricity alone. However, even if that is the case, it might still be preferable given the need for long term energy storage, system ramping and other system optimisation challenges.
Here again the answer is not so straightforward!
The renewable electricity that goes into making green hydrogen may be generated a very long way from the place where it is used. And it is a lot cheaper to transport hydrogen than electricity over long distances. So green hydrogen may become a global commodity being produced where electricity is cheap and delivered where it is needed, when it is needed. It can then play an increasingly valuable role either as peaking generation or to fuel micro CHP fuel cells providing heat and power in our homes and avoiding electrical system losses.
Given the recent developments in green hydrogen production both globally and here in the UK, it is not inconceivable that green hydrogen could one day not only be cheaper than locally generated electricity, it may even be as cheap as natural gas is today.
Can Scotland demonstrate the transition from black to green gold?
Initiatives such as the REFlex project in Orkney are demonstrating the contribution hydrogen can make as part of an integrated energy system solution to avoiding curtailment of excess wind, and the Dolphyn project near Aberdeen will demonstrate a dedicated offshore wind farm producing green hydrogen.
Even with the recently announced Eastern Link interconnector which will deliver up to 2GW of wind power from Scotland to the South of the UK, there is going to be a lot of excess generation as we develop more wind over the coming decades.
That is a good thing.
Maybe Scotland’s wind resource will become the new green gold; Scotland is certainly well placed in terms not only of natural resources, but also of the engineering skill base developed over decades to exploit the black gold of the North Sea.
And so, it is encouraging to see companies like Scottish Power committing not only to being a 100% renewable energy supplier, but also making substantial investments in renewable generation and green hydrogen. Let’s hope that our governments, both in Scotland and the wider UK, provide the necessary regulatory and other support to accelerate this transition.
