Want to do your bit at home to save the planet, and be confident that your effort is worthwhile?
Research from the Co-op Bank suggests that the UK public plans to spend more than £13b to make their homes greener in 2008 (an average of ~£550 per house per year). Two-thirds claimed that they had reduced their carbon footprint in the past year.
Here I explore two opposite ends of the spectrum
when it comes to cost and complexity,
composting your kitchen waste vs domestic solar power,
but both in the spirit of "think global, act local."
Composting
Composting your kitchen and garden waste saves landfill space,
methane generation and global warming.
Adding your shredded junk mail and sensitive documents protects you from ID
theft, and helps the composting!
Composting at home is mainly aerobic (ie has plenty of air)
and thus produces mainly CO2 (and a little compost).
Dumping your waste in the bin for the council to collect
results in much or all of it ending up in scarce landfill
where it produces methane by anaerobic (airless, ie oxygen-free) breakdown
of which 97% escapes into the atmosphere,
and also toxic compounds that can leach into the surrounding area.
CO2 is a greenhouse gas,
but is far less potent (200x) than methane for retaining heat in the atmosphere.
With a rat-proofed garden compost bin even cooked food can be composted,
and without a garden an outdoor or indoor wormery can be used to compost uncooked food.
Well-managed composting does not smell or present a hygiene problem,
and is cheap or free.
So get to it and help the planet!
Domestic Solar Power/Heat
I'd like to reduce my consumption of power, mainly mains gas and electricity,
by generating some renewably. Millions of local domestic power generation
facilities might also help increase electricity supply robustness against
peak load, storm or even sabotage, in the same way that the distributed nature
of the Internet makes it robust in the face of point failures. However,
it is possible that I might be expensively failing to save the planet
and my money...
Domestic solar heating and electricity generation will not save
money but can reduce overall CO2 emissions.
A domestic solar power system will likely not pay for itself in the UK.
In September 2005 a group of well-respected UK academics reported that the payback period for an investment in a solar PV system in the UK was 47 years.
The equipment life might be 25+ years, so the chance of financial payback is low.
Government grants improve the position, and there are reasons other than
purely financial for installing solar PV (photovoltaics aka solar cells/panels),
but high capital and financing costs and sunlight of perhaps 2.5 hours per day
may simply mean that pure financial payback never arrives for a small domestic installation.
On the other hand, if your aim is to reduce your total carbon/energy footprint,
then PV may save its manufacturing footprint in the first few years of a 25-year life.
Solar water heating looks a lot more attractive than PV in terms of financial payback,
maybe much less than 10 years, and it is very likely that the equipment will
last at least that long. And you should be able to recover/save the
manufacturing 'carbon' input with no great difficulty within a year or so.
But of course you don't get much hot water when you most want it, ie in winter.
The study Can PV or Solar Thermal be cost effective ways of reducing CO2 emissions for residential buildings? (2006)
reports that the carbon payback for [a] solar thermal system is 2
years, [and a] BIPV system has a carbon payback of 6 years. Simple
economic payback times for both systems are more than 50 years.
Calculations considering the current UK energy price increase (10%/yr),
reduce the economic payback time for the PV roof to under 30 years. The
costs to reduce overall carbon dioxide emissions using a BIPV roof are
£196/tonne CO2, solar thermal
individual systems at £65/tonne CO2 and
community solar thermal at £38/tonne
CO2. The current spot market price for
CO2 is £15/tonne
CO2 (20). Capital costs for PV systems in
particular must be significantly reduced for them to be a
cost-effective way to reduce CO2.
Hybrid solar PV/thermal (PV/T) systems may make better sense
since the unused (heat) energy that reduces the performance of PV
can be usefully absorbed into the thermal system instead.
In other words, you are very unlikely to save significant
money with domestic solar energy in the UK, but you are more likely to
help reduce CO2 emissions,
and there may be other benefits.
(In spite of this apparent doom and gloom, I'm running a small solar PV power pilot project, based on low-voltage lighting,
I'm making my office zero-carbon,
and I'm looking to see what it would take to get really LZC (Low/Zero-Carbon) at home.)
What can really save you some money, and maybe the planet,
is to eliminate waste by improving thermal insulation
and saving electricity,
eg with the benefit of a gadget such as the
PM230 kWh meter,
or the 2000MU-UK meter from Maplin,
or a "Kill-a-Watt".
Did you know that your microwave oven may use more energy in its lifetime
running the clock 24x7 than you ever use to heat food, for example?
Turn stuff off at the wall when you're not using it.
Also, consider switching to a 'green' electricity supplier such as Ecotricity that's actually building new capacity, eliminating a chunk of your carbon footprint in one blow.
