Hi
I have been researching possibilities for energy generation for my future smallholding.
And thought I had a cunning plan. But I came across a number of ideas about the future of electricity
generation and future models that the power suppliers are planning. This post is a
mish-mash of what I discovered and think could happen. I compare nuclear with CHP as it
current topic for our masters.
Any system has to consider a number of parameters :-
Baseload,peak use(spinning reserve),robustness(reliability),capital cost,energy cost,carbon
emmissions, transmission losses and compatibility with intermittent sources/renewables.
The system coming to a home near you soon delivers on all these.
Suppose the politicians(really legislation generation humanoids). Decide we need a new power
station - coal,gas,oil,nuclear. Is there a better option ?
Fuel cells are used domestically in japan and there are current contracts in the UK for many
thousands. The newer models and current units in resarch can get 65% electrical efficiency
from natural gas. But for the model considered 33 % or less would be O.K.Having higher
efficiency is useful but not vital.See below for expected costs per kWh capital cost.Note
overall efficiency for water output at 80 C.
http://en.wikipedia.org/wiki/Micro_combined_heat_and_powerThe system in mind would have a 5kW electrical output and produce 10kW of heat(33% electrical efficiency).
It could operate off grid and provide electricity and heat - a useful fall back option. It would
provide heat@15kW i.e. using the electrical output to add to the heat. Or up to 5kW of electricity
i.e. it could modulate the percentage of electricity used.For a 1 MW power station we would need
200,000 CHP house holds(from 30,000,000. Does not include spinning reserve)
So how would you replace a power station with a distributed CHP fuel cell grid and how would it
compare ?
By installing 200,000 units free in ex NIMBY households(1/10 cost of nuclear).
Baseload Nuclear nearly perfect. Fuel cell system more than perfect The distributed system will
always generate heat for heating when required or hot water storage tank if not. The gas that
is burnt in a gas generation plant/nuclear wastes the heat CHP always uses it.(at least 2x more efficient)
peak use(spinning reserve) Nuclear useless. Fuel cell system nearly perfect. It can be arranged that
some systems will always be using electricity for heat. Switching this heat off means instant
export to the grid. Other units can be turned on for known peak periods. Capital cost of spinning reserve
is £2500 per household. CHP would not require this. As plant need replacing we save the replacement cost.
robustness(reliability) Nuclear very good Fuel cell system nearly perfect. Distributed system and standalone
off grid operation provides high availability. If one unit fails no impact on system. Failed system still
operates from grid electricity.
Energy cost Nuclear 3.5 p/kWh Fuel cell system 3.5 p/kWh (best guess for both)
carbon emmissions Nuclear build and fuel preparation cause C02 emmissions. Fuel cell system CO2 emmision low
as gas is used(but 2x efficiency of current gas plant)
compatibility with intermittent sources/renewables Nuclear forget it. Fuel cell system excellent. system
can absorb all renewable energy generated by modulation of gas used.
Transmission losses Nuclear centralised plant means highest losses. Fuel cell system can be controlled
to produce electricity close to where it is required transmission losses low.
Capital cost per kWh installed. Nuclear = $7000. Fuel cell system = $750.I dont belieeeve it !
Current energy suppliers are considering giving customers free CHP fuel cell boilers
as a cost effective option. This is cheaper that building power plants.Gas use will
either halve or power output with the same gas burnt will double.
Regards
Richard