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Keith MacLean : Big Choices

At last week’s 2013 Annual Conference for PRASEG, the UK parliamentary sustainable energy group, Keith MacLean from Scottish and Southern Energy outlined (see below) the major pathways for domestic (residential) energy, currently dependent on both a gas grid and a power grid.

He said that decarbonising heat requires significant, strategic infrastructure decisions on the various proposals and technology choices put forward, as “these options are incompatible”. He said that the UK “need to facilitate more towards ONE of those scenarios/configurations [for provision for heating at home] as they are mutually exclusive”.

There has been a commitment from Central Government in the UK to the concept of electrification of the energy requirements of both the transport and heat sectors, and Keith MacLean painted a scenario that could see the nation’s households ditching their gas central heating boilers for heat pumps in accord with that vision. Next, “the District Heating (DH) movement could take off, [where you stop using your heat pump and take local piped heat from a Combined Heat and Power (CHP) plant] until there is no spare market capacity. Then [big utilities] could start pumping biogas and hydrogen into the gas grid, and you get your boiler back !”

Since I view gas grid injection of Renewable Gas feedstocks as a potential way to easily decarbonise the gas supply, and as Keith MacLean said in his panel presentation, “The real opportunity to make a difference in our domestic [residential] energy consumption is in heat rather than power”, I sought him out during the drinks reception after the event, to compare notes.

I explained that I appreciate the awkward problem he posed, and that my continuing research interest is in Renewable Gas, which includes Renewable Hydrogen, BioHydrogen and BioMethane. I said I had been reading up on and speaking with some of those doing Hydrogen injection into the gas grid, and it looks like a useful way to decarbonise gas.

I said that if we could get 5% of the gas grid supply replaced with hydrogen…”Yes”, said Keith, “we wouldn’t even need to change appliances at those levels”… and then top up with biogas and other industrial gas streams, we could decarbonise the grid by around 20% without breaking into a sweat. At this point, Keith MacLean started nodding healhily, and a woman from a communications company standing near us started to zone out, so I figured this was getting really interesting. “And that would be significant”, I accented, but by this time she was almost asleep on her feet.

With such important decisions ahead of us, it seems that people could be paying a bit more attention to these questions. These are, after all, big choices.

What did Keith mean by “The District Heating movement” ? Well, Dave Andrews of Clean Power (Finning Power Systems), had offered to give a very short presentation at the event. Here was his proposed title :-
“Indicative costs of decarbonizing European city heating with electrical distribution compared to district heating pipe distribution of large scale wind energy and with particular attention to transition to the above methods and energy storage costs to address intermittency and variability of wind power.”

This would have been an assessment of the relative costs of decarbonising European city heating with either :-

Strategy 1)

“Gas-fired Combined Cycle Gas Turbine (CCGT) generation plant plus domestic (residential sector) electric heat pumps as the transition solution; and in the long term, large scale wind energy replacing the CCGT – which is retained as back up for low wind situations; and with pumped hydro electrical storage to deal with intermittency /variability of wind energy and to reduce back up fuel usage.”


Strategy 2)

“CCGT Combined Heat and Power (CHP) plus district heat (DH) as the transition solution; and in the long term, large scale wind energy replacing the CCGT CHP heat but with the CCGT retained as back up for low wind situations and with hot water energy storage to deal with intermittency / variability and to reduce back up fuel usage.”

With “the impact of [a programme of building retrofits for] insulation on each strategy is also assessed.”

Dave’s European research background is of relevance here, as co-author of a 215-pager SETIS programme paper complete with pretty diagrams :-

Although Dave Andrews was also at the PRASEG drinks reception, he didn’t get the opportunity to address the conference. Which was a shame as his shirt was electric.

10 July 2013
“Keeping the Lights on: At What Cost?”
Parliamentary Renewable and Sustainable Energy Group
Annual Conference

Second Panel Discussion
Chaired by Baroness Maddock
“Negawatts: Decentralising and reducing demand – essential or ephemeral ?”

[Note : The term “negawatt” denotes a negative watt hour – produced by a reduction in power or gas demand. ]


Keith MacLean, Scottish and Southern Energy

Decentralisation and Demand Reduction [should only be done where] it makes sense. Answers [to the question of negawatts] are very different if looking at Heat and Power. Heat is something far more readily stored that electricity is. Can be used to help balance [the electricity demand profile]. And heat is already very localised [therefore adding to optimising local response]. Some are going in the other direction – looking at district [scale] heating (DH) [using the more efficient system of Combined Heat and Power (CHP)]. Never forget the option to convert from electricity to heat and back to electricity to balance [the grid]. Average household uses 3 MWh (megawatt hours) of electricity [per year] and 15 MWh of heat. The real opportunity is heat. New homes reduce this to about 1 [MWh]. Those built to the new 2016 housing regulations on Zero Carbon Homes, should use around zero. The real opportunity to make a difference in our domestic [residential] energy consumption is in heat rather than power. Reducing consumption not always the right solution. With intermittents [renewable energy] want to switch ON at some times [to soak up cheap wind power in windy conditions]. [A lot of talk about National Grid having to do load] balancing [on the scale of] seconds, minutes and hours. Far more fundamental is the overall system adequacy – a bigger challenge – the long-term needs of the consumer. Keeping the lights from going out by telling people to turn off the lights is not a good way of doing it. There is justifiable demand [for a range of energy services]. […] I don’t think we’re politically brave enough to vary the [electricity] prices enough to make changes. We need to look at ways of aggregating and automating Demand Side Response. Need to be prepared to legislate and regulate if that is the right solution.


Questions from the Floor

Question from John Gibbons of the University of Edinburgh

The decarbonisation of heat. Will we be successful any time soon ?

Answer from Keith MacLean

[…] Decarbonising heat – [strategic] infrastructure decisions. For example, [we could go down the route of ditching Natural Gas central heating] boilers for heat pumps [as the UK Government and National Grid have modelled and projected]. Then the District Heating (DH) movement could take off [and you ditch your heat pump at home], until there is no spare market capacity. Then [big utilities] could start pumping biogas and hydrogen into the gas grid, and you get your boiler back ! Need to facilitate more towards ONE of those scenarios/configurations [for provision for heating at home] as mutually exclusive. Need to address in terms of infrastructure since these options are incompatible.

Answer from Dave Openshaw, Future Networks, UK Power Network

Lifestyle decision – scope for [action on] heat more than for electricity. Demand Management – managing that Demand Side Reduction and Demand Reduction when need it. Bringing forward use of electricity [in variety of new applications] when know over-supply [from renewable energy, supplied at negative cost].


3 replies on “Keith MacLean : Big Choices”

Hi Jo, excellent article, as always, and thanks for good links. Sadly, I think the choice has already been made between DH and heat pumps. The incentives for biomass and waste fuelled power stations are mainly loaded onto the electricity production. So using heat from these (steam cycle) stations becomes costly since supplying heat at DH temperatures would reduce the electric output and therefore reduce the main revenue.
Combine this with the ongoing granting of consent for power stations distant from heat loads and it seems difficult to see how DH can grow to a significant size in the UK. My feeling is we will end up with a few very localised DH schemes.

Do you think boilers would be a good use of renewable gas?

What do you think of Zero Carbon Britain’s latest report?

Thanks again, Rae.

Hi Rae,

Whenever I go to meetings where energy policy is discussed, there is an view that a good proportion of heat and transport needs will be provided in future by electricity. I’m calling this “Electrificandum”, the imperative to electrify. There are major snags with the modelling of this future, however, as is beginning to become clear – for example, batteries of a suitable size and type for vehicles are still expected to use a lot of rare materials. Plus, manufacturing and marketing new electric vehicles and recycling the old internal combustion engine models will take a lot of time. In the case of heat, there is the assumption that in future, most buildings will have such a high standard of thermal protection (insulation, insulation, insulation) that they won’t need space heating most of the time. Because the main use of Natural Gas in the home is space heating, if homes no longer need heating, then it would be more efficient to heat, cook and make hot water with electricity and stop providing Natural Gas to people at home by the pipe network. But dismantling such a huge infrastructure as the gas grid is not something that should be done lightly, especially since rates of home insulation have stalled.

It’s easy to market heat pumps, which would constitute a minor change to the fabric of a building, and a relatively minor capital cost to homeowners; rather than installing District Heating (DH) piping networks and local community Combined Heat and Power (CHP) stations to supply the heat locally – a cost that would be borne by Local Authorities (strapped for cash, currently) and/or infrastructure companies (and where’s the stimulus for the investment ?). Unless there is a big push and some policy development and “stakeholder engagement”, like you I cannot see District Heating becoming common. Large community housing projects already use CHP, and so DH would be logical.

If we are going to burn increasing amounts of biomass and waste (until the waste cliff is reached – as projected by the EU – as various waste reduction Directives are enacted) for power generation, this is highly inefficient, and should be done as co-generation. Gasification of biomass and waste is likely to lead to more efficient energy conversion than straight combustion. If biologically-resourced Renewable Gas (biogas, biomethane) continues to be developed, CHP/DH should be the only option for its use (aside from gas grid injection) as otherwise the efficiencies of lifecycle energy conversion will be very poor. With biomass, the greatest efficiencies should always be strived for, otherwise we commit to burning too much of it.

Efficiency questions are less of an issue for other forms of Renewable Gas, which are often produced at industrial scale, requiring little energy input, so straight combustion in Combined Cycle Gas Turbine plant without heat capture for heating would be acceptable. If Renewable Gas is produced in an industrial plant, however, there are likely to be heating needs in the same facility, so if the heat of combustion can be captured and used, it would be helpful.

I haven’t read the latest Zero Carbon Britain report in detail yet, but I have downloaded it ! Anything I should look out for in particular ?

PS I see ZCB 2013 has Renewable Gas in it !

I would tend to agree with Keith Maclean’s assessment, that more CHP or district heating is a good idea. Its the quickest and easiest way to bring down carbon emissions, as well as leading to a better more distributed electricity generating grid. i.e. in an emergency, such as a winters night with no wind, every one of those micro-CHP/DH systems suddenly becomes a small mini-power station, enough of them acting together could easily push us through any such period.

Pumping renewable gas into the gas network is also an idea I’d endorse, as it builds on a system we’ve already got installed. Also people often forget that more of the UK’s energy is consumed providing heat in winter, often via gas, than “keeping the lights on” via electricity.

As for heat pumps I’m a little more skeptical, as I outline in the article below. The problem with domestic heat pumps in the UK is that their COP is dependent on the demand temperature and given that most UK homes are heated by radiators rather than underfloor or air conditioning, you’re unlikely to get a very good COP (to the point where once you factor in the average efficiency of a UK power station, they work out as producing more CO2 than a gas boiler!).

Thus you’d need to gut most of the UK’s homes and reinstall the domestic heating system (and in many of the UK’s older properties it would be easier to simply flatten the house and build a zero-carbon home than do that!). Inevitably swapping a gas boiler for a CHP unit or putting a pipe under the street from a DH plant is going to be cheaper and more practical than doing that.

Also, Heat pumps need to draw electricity from the grid. The last thing we need in an energy crisis is a vast network of these drawing more power from the grid, likely at the very time it will be under maximum pressure (while CHP can help balance the grid).

Don’t get me wrong, heat pumps have a role, particularly for homes that are close to renewable energy sources and off the gas grid (e.g. rural areas) or zero-carbon homes that have very little heat demand anyway. But in general terms, I’d come down on the side of CHP/DH.

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