Hydrogen for grid-2-gas load balancing in future energy

systems

M E Crowther – General ManagerGASTEC at CRE Ltd15th September 2011

What are the likely total energy vectors of the future?

Electricity - expensive to deliver and effectively cannot be stored. Inter-seasonal storage the greatest challenge.

Biogas - tends to easiest derived from food competitive sources

Hot water - very expensive to deliver

Hydrogen - ???

Recent hydrogen studies

Hyways - the EU-wide study on hydrogen powered road transport

&

NaturalHy - the EU-wide study on adding up to 50% hydrogen to distributed gas

…have highlighted the safe and cost-effective nature of generating hydrogen.

However, surely this is only part of the story?

If the UK is going to the trouble of introducing a network of hydrogen filling stations

and/or

Adding 50% hydrogen to Natural Gas (ie re-inventing Town’s Gas)

Then surely it could be easier and cheaper to simply distribute 100% hydrogen?

What next?

What next?

% Hydrogen % Nat Gas CV kWh/m3 CO2 kg /m3 CO2 kg/kWhC % of Nat Gas

per kWh

0 100 11.0 2.08 0.190 100%

10 90 10.2 1.88 0.183 96%

20 80 9.5 1.67 0.176 92%

30 70 8.8 1.46 0.167 88%

40 60 8.0 1.25 0.156 82%

50 50 7.3 1.04 0.143 75%

60 40 6.6 0.83 0.127 67%

70 30 5.8 0.63 0.107 57%

80 20 5.1 0.42 0.082 43%

90 10 4.3 0.21 0.048 25%

100 0 3.6 0.00 0.000 0%

Table showing the non-linear benefits of adding hydrogen at Natural Gas.

Thus 20%v/v hydrogen (upper limit without full appliance conversion) only produces 8% reduction in carbon emissions

Introduce conversion programmes to 100% hydrogen, piecemeal across the UK, using existing Local Distribution Zones to supply:-

Existing Natural Gas users Road Transport Filling Stations New uses of hydrogen in low carbon industries

The GaC concept

Where will the hydrogen come from?

We could derive the hydrogen from:- Excess renewables

Wind Wave Solar PV >83% eff HHV (photo)

Biomass via gasification

Biogas from Anaerobic Digestion

Where else could the hydrogen come from?

From fossil fuel using Carbon Capture and Storage

Natural gas via reform & shift

Coal/Coke via gasification and shift

A true competitive free market can exist as hydrogen can be produced,stored, traded and sold ‘at leisure’, similarly to oil or natural gas.

I think we have established that there are several competitive routes to hydrogen.

Additionally….

….hydrogen solves ALL the problems of seasonality with a few simple storage caverns of modest dimensions.

So?

Change-over at the LDZ scale means….

The transition can be carried out piecemeal – eg Bristol, or Newcastle

No ‘change of use’ will be necessary for the NTS

No disruption of international carriage of Natural Gas or supplies to existing power stations

Householder choices

Householders can either use H2 boilers or Fuel Cells to generate their heat and power

Fuel cells close-coupled to heat pumps offer even more exciting opportunities

To repeat, we are NOT suggesting (at this stage) a national network of high pressure hydrogen lines…..

….because this is expensive and technically challenging.

We are suggesting the re-purposing of the existing local natural gas distribution zones to hydrogen.

The national (or even international) network well may arise but we are trying to emulate most historical fluid grids ie start small and interconnect latter.

Distribution

Whilst hydrogen has a CV of only 13,000kJ/m3 compared to 39,000 kJ/m3 for natural gas, it is 1/10th the density; so it is envisaged that with energy efficiency measures and local attention to system integrity, many existing PE grids will require little reinforcement.

Distribution

The Wobbe Number of methane and hydrogen are not that different:-

So the system would require only a 10% uplift in capacity

Distribution

Wobbe No SI units

Methane 53.2

Hydrogen 50.2

Each local hydrogen network would have its own storage facility for seasonal variants.

It is suggested that Hydrogen has a ‘green’ footprint for long term energy storage if compared to water pump storage (flooded valleys) or exotic batteries (exotic metals).

Distribution

To convert an LDZ to hydrogen would require:-

1. Its disconnection from the NTS2. Provision of H2 production facility3. Construction of local storage4. Pressure testing with hydrogen & confirmation of integrity5. Reinforcement of pipework capacity6. Replacement of meters and local appliances

It is not a vast exercise compared to full electrification.

Distribution

The advantages

To consider in detail the advantages of distributed hydrogen….

The UK gas plus electricity demand (minus gas to power stations) is strongly seasonal. Daily gas peaks can be even twice these values.

The demand

If this seasonal gas load were going to be replaced by electricity, it would require a massive (manifold 3 to 4.5) increase in electrical generation and distribution facilities, which would only be used very intermittently and to a frequency that it is extremely difficult to predict.

Very approximately, the cost ratio of distributing energy is as follows (where distribution includes fees for stand-by capacity etc):-

• Natural Gas x pence/kWh (hydrogen will be similar)• Electricity 7x pence/kWh• Hot water 49x pence/kWh

This can be seen in current UK fuel costs (excluding billing)

The Finances

p/kWh Beach/stationRetail O/H +

marginSystem TOTAL retail

Gas 1.6 1.5 1 4.1

Electricity 3.5 2.2 5.8 11.5

Ratio 6

UK retail fuel cost 2011…indicative

The Finances

Further more what happens to the thermal efficiency of gas or coal plant with CCS when operated at steep ramp rates?

To cope with peak electrical demands in an “all-electric” world, means building either….

– Coal + CCS at £3,000/kW or– a ‘surplus’ of wind turbines or– significant storage of currently unproven design.

…which would only operate profitably for a few days/year; a deeply unattractive option!

The Finances

If a high percentage of our electricity arises from :-

• Wind at 30% availability• Tidal at widely swinging values (eg Severn barrage 8.2GW to zero, 4

times/day)

Then the situation becomes even more difficult. We also have to ask ourselves:- Will the peak winter loads (eg long-lasting Siberian High) coincide with low wind speeds? What physical area would these ‘highs’ cover? and What would be the true reliability of an EU supergrid?

Inter-seasonal storage of hydrogen solves all this.

The Finances

Hydrogen can be safely stored as demonstrated at:-

• Billingham• In Germany, and more recently• By Praxair in Texas

By uncoupling supply and demand of/for hydrogen, a free market can exist in both.

The Challenges

The level of this uncoupling can be subject to debate.

The author suggests about 3600kWh per person - ie about 95kg H2/person would suffice….

(try to imagine a cube of side 850m at 80barg for the whole of the UK!)

The Challenges

p/kWh Beach/station Retail O/H + marginSystem (Inc

storage) TOTAL retail

Gas 1.6 1.5 1 4.1

Hydrogen 4.5 1.7 2 8.2

Electricity 3.5 2.2 5.8 11.5

Ratio 2.9

Looking at some costs: let us say that hydrogen, costs 4.5p/kWh to generate (ref US data from Nat Gas +CCS) and is twice the price of Nat gas to distribute (including storage) (Prices 2011)

We now have a ‘competitive zero carbon fuel’ ….….(well almost! And certainly competitive with projected future electricity costs, as these are bound to rise)

At what price?

At what price?

$/kg $/kWh £/kWh (theory)Central SMR (Nat Gas) $ 1.47 $ 0.038 £ 0.025 Distributed SMR (Nat Gas) $ 2.63 $ 0.068 £ 0.044 Coal gas wf CCS $ 1.82 $ 0.047 £ 0.030 Coal gas wfo CCS $ 1.21 $ 0.031 £ 0.020 Biomass $ 1.44 $ 0.037 £ 0.024 Distributed electrolysis $ 6.75 $ 0.174 £ 0.113 Central wind $ 3.82 $ 0.098 £ 0.064 Distributed Wind $ 7.26 $ 0.187 £ 0.121 Nuclear $ 1.39 $ 0.036 £ 0.023

38.89 kWh/kg ref US EIA 2008 In practice higher

Further US EIA data on projected hydrogen production costs;2008

MW Dist km Cost £/MW.km

HVDC Brit Ned 1,000 240 £540,000,000 £2,250 Holland-UK Sub-sea

HVAC Scotland 2,700 220 £350,000,000 £589 Beauly-Denny,

Scotland

Nat Gas S Wales 24,000 316 £700,000,000 £92 Milford Haven to Glos

Comparative UK energy transmission costs

At what price?

Indicative result of investing £1000million

1)250MW of nuclear power station; CO2 saved 900,000 t/y of electricity2)400MW of offshore wind turbines;CO2 saved 550,000t/y of electricity

3)1000MW of hydrogen production (from pet: coke) and its distribution to 250,000homes and 114garages eg Leeds, Manchester, Sheffield or Edinburgh;CO2 saved~2,000,000t/y og gas and oil (inc: contribution of ~£100m to CCS disposal site itself)

At what price?

Estimated cost of electricity from biomass (ref Mott McDonald for DECC June 2010)

Scale 100 MW

Capital £ 250,000,000

Annual Depreciation £ 12,500,000

Annual interest 12% £ 30,000,000

O&M 5% £ 12,500,000

Total annual charge £ 55,000,000

Cost of biomass £ 60.00 per tonne

Gross CV 3.472 kWh/kg

Cost £ 0.0173

Eff GCV 48%

Cost of fuel £ 0.036

Cost of electricity by operating hours/yr

1500 £ 0.403

3000 £ 0.219

6000 £ 0.128

7500 £ 0.109

Possible ‘back-up’ costs of low carbon biomass electricity

At what price?

Estimated cost of hydrogen from electrolysis Scale 1000 MW

Capital £ 600,000,000 Uncertain

Annual Depreciation £ 30,000,000

Annual interest 12% £ 72,000,000

O&M 5% £ 30,000,000

Total annual charge £ 132,000,000

Cost of electricity £ 0.072 per kWh

Twice the biomass fuel cost

Eff GCV 83%

Cost of fuel £ 0.087 Cost of hydrogen by operating hours/yr

1500 £ 0.175

3000 £ 0.131

6000 £ 0.109

7500 £ 0.104

By not taking carbon into the community we can immediately “know” the true extent of carbon saving.

We are no longer dependent upon lifestyle choices.

All static gas use is replaced with hydrogen use.

Carbon savings must, therefore, be delivered.

Other advantages

The transport sector can be converted to hydrogen vehicles via the UK’s existing 9,000 garages.

Advantages:-

Refuelling pattern & hence lifestyle is the same as petrol & diesel

Low cost hydrogen immediately available Do not need to store large quantities of HP hydrogen on site (only buffer quantities required)

Transport

New opportunities for the gas industry in new ‘low carbon’ heavy industries to replace coal and coke and take the UK to the ‘cutting edge’, as it was at the birth of the gas industry eg:-

iron & steel glass refractories etc

Industry

Hydrogen:-NOT Toxic, Carcinogenic or RadioactiveIt has no military useDoes not leak significantly through walls of PE pipesDiffuses away more quickly than methaneDoes not embrittle steel below 25bargWas 50% v/v Town’s GasCan be carried safely through the existing gas networkBUT does leak more quickly though holes created by corrosion/3rd party damage and is flammable with a low ignition energy thus a full risk assessment of 100% hydrogen still needed.

Safety

Both full scale CHP and mCHP save carbon right now in 2011 because of the high carbon intensity of UK electricity (typically 0.52kg/kWh)

This situation is likely to last for several years, BUT as the grid is decarbonised (as must occur to meet Government policy) the net savings will decrease until, at an electrical grid intensity of about 0.22kg/kWh, even simple natural gas-fired CHP is carbon neutral.

Widespread introduction of Fuel Cell CHP

Let us investigate the possibility of the widespread introduction of local PEM fuel fuels consuming hydrogen as a source of local heat and power.

PEM fuel cells:-

Simplest and most proven of fuel cell technology. Operational temperature compatible with small scale

heating systems. Good electrical efficiency Acceptable cost

PEM fuel cells

PEM fuel cells

Ref University of Cambridge DoITPoMS

Fuel cell system costs have decreased significantly over the past several years, and although still nearly twice as high as those for internal combustion engines are falling fast

Fuel Cells – how much?

Source: USDOE, Hydrogen Program Records 5005, 8002, 8019, and 9012 (http://www.hydrogen.energy.gov/program_records.html)

mCHP    House annual heat demand 12000kWhFuel cell heat efficiency 40.00% Hydrogen use 30000kWhCost of hydrogen £0.085/kWhAnnual cost of hydrogen £2,550 Fuel cell electricity efficiency 40.00% Electricity production 12000kWhCost of electricity £0.20/kWhAnnual electricity used 4500kWhElectricity imported 2000kWhCost of elec imports £400 Electricity exported 9500 FIT for export electricity £0.13/kWhAnnual income from FIT £1,235 Net Cost of heat £1,315 Net cost of heat to home £0.11/kWhTotal energy expenditure £1,715 

Indicative economics of a property purchasing hydrogen at 8.5p/kWh, and using a fuel cell microCHP or a condensing boiler (fuel cell heat efficiency is apparently modest due to the use of a boost burner)

At home?

The possibilities of fuel cell plus heat pump are even more exciting!

Other fuel cell options…

Similar arguments can be advanced for the use of fuel cells in the transport sector.

Fuel Cell ASHPHydrogen 5000 kWh/yHigh grade heat for DHW & winter days 1750 kWh/yElectricity 2500 kWh/yCOP for warmer days 3.0Heat delivered from ASHP 7500 kWh/yAdditional condensate heat 500 kWh/yOverall spf 1.95

Electric Space heating:-Resistance heating - simple but expensive ASHP - simple installation, but annual efficiency less than GSHP (both of complex installation) Requires substantial capacity in BOTH generation and transmission/distribution to meet winter peak.

Transport:-Batteries are well proven, but can be heavy and are always likely to be of short range.

In other words, an expensive infrastructure with no strategic energy reserve.

Pros/Cons of an all-electric approach:-

Space heating:- Simple compliance with winter peaks and no need to re-enforce

local wires Simple boiler replacement in the home with high temperature

radiators Uses much of local (ie – low pressure) natural gas infrastructure

Transport:- Simple replacement of pumps at existing vehicle forecourts with

compressed hydrogen units

In other words, modest cost infrastructure with simple strategic energy reserve.

Pros/Cons of mixed hydrogen / electric approach with local fuel cells

Let us not close our minds to the potential for hydrogen as an alternative low carbon

energy vector.

The future

Thank you!

www.gastecuk.com

enquiries@gastecuk.com

+44 1242 677877