reducing always comes first... 

It is generally cheaper and easier to save energy than to generate it from genuinely renewable resources (see housekeeping section below).  In the search for solutions to climate change too much emphasis has been put on the more headline grabbing renewable energy and not enough on the boring details of using less in the first place. 

In the huge majority of cases the best, easiest and cheapest way of reducing our carbon footprint is by first using energy more carefully.  This has been demonstrated time and again at Riverford:

• we spent £20,000 (largely from tax-payers money) fitting photovoltaic cells to the roof of our farm restaurant, the Field Kitchen.  These save approx 2 tonnes of CO₂/year due to a reduction in our use of electricity generated by fossil fuel.  Similar savings were achieved by changing the building's light bulbs at a cost of £200.
• Other less visible measures have included: improving insulation; installing an office passive ventilation system instead of air conditioning; reclaiming waste heat from refrigeration equipment and many more - all have proved much cheaper, easier and less intrusive than putting up windmills.

After eighteen months of concentrating on saving energy this is still the most fruitful direction for reducing our environmental impact but we are now starting to consider the potential for alternative renewable energy.

With the exception of nuclear and geothermal all our energy ultimately comes from the sun. In the case of fossil fuels it has been harvested and preserved over millions of years to create an incredibly concentrated and convenient energy source which has fuelled the industrial revolution and enabled the rapid growth of developed economies.  It would take one of us a month of hard labour to expend the energy contained in a gallon of oil, yet even at $100 a barrel, it would take less than half an hour on an average wage in developed economies to buy that gallon.  Oil is absurdly cheap.  About half (the easily extracted half) of it is gone and demand is still rising fast. There is no doubt that it will become much more expensive.  I expect it to be $1000 a barrel in my lifetime.  Any sensible government, business or individual should have a long term plan for reducing dependence on oil, regardless of any consideration of climate change.  Though they should be secondary to saving energy, renewable fuels should be part of that plan.

Because fossil fuels are so cheap, most renewables we have considered seem expensive by comparison:

photovoltaic cells

There is the argument that with greater investment and larger scale manufacture the price of PV cells would come down (and it is doing so) but as things stand they appear to offer a very low return in CO₂ saving for pounds spent.  Given the technology available today we will not be installing any more.

anaerobic digestion (AD)

This is a well proven technology used extensively in China and Germany on both a small and medium scale. We have been investigating it for several years but have been put off by the poor track record that it has in this country. The fundamental principle is to allow organic matter to ferment under warm, anaerobic (no oxygen) conditions so that most of its inherent energy is released as methane which can then be used as a fuel for generating electricity, cooking, heating or can be compressed and used as a transport fuel.

Cow manure, of which we have plenty, is unfortunately a relatively poor fuel for anaerobic digestion because the cow’s gut is so efficient that most of the energy has already been extracted.  Some systems grow crops like grass silage to feed the digester but this suffers from many of the criticisms of other biofuels; namely that it competes for land use with food crops and itself uses energy.  We are looking at the possibility of working with other local businesses to collect and digest their waste in combination with cow and horse manure.  There are technical and regulatory problems to overcome but AD does have the potential to generate a significant portion of our electricity and plenty of heat, or to power some of our road vehicles.

wind energy

Wind energy using large, modern windmills in appropriate areas can give good returns on capital and could feasibly generate 100% of our electricity in the UK. Public opinion is divided about whether this is a good enough argument given the visual impact and to a lesser extent noise. Though the commercial return can be good, the planning issues are such that leading installers would rather do business elsewhere in the world with a lower regulatory burden. We have a suitable site on the farm but I am advised that the application for planning permission is not only lengthy and difficult but can also become personal and unpleasant as people take sides and dig in. For this reason we plan to continue focusing on energy saving ahead of windmills, for the time being at least.

biofuels

Fuels derived from recently living plant matter are broadly divided into liquid biofuels for transport (click here for transport fuels) and biomass for heat generation:

using wood as a low grade heating fuel. Most trees are grown on land that is not suitable for crop production. Maintaining and harvesting them has a low energy cost and can have a low environmental impact. There are systems for burning wood to generate electricity but generally, because of its bulky nature this fuel is best suited to local, predominantly rural use in small to medium sized heating schemes. We have substantial areas of woodland on the farm in addition to the wood generated by managing hedgerows, and waste, low grade wood from the pallets and boxes that our imports often arrive in. Over the next year we will install a wood chip boiler to replace four oil boilers, as well as highly efficient gasifying log burners to heat on-farm accommodation.  

conclusion

We still have a lot of work to do on reducing our energy demand and this will continue to be our top priority.  Over the next decade we plan to reduce the impact of our remaining demand by using the following renewable technologies:

• Short term (two years): Use of on farm woodland as a source for heating will reduce our CO₂ emissions by approx 50 tonnes/year
• Medium term (two to four years): on farm anaerobic digestion
• Longer term (three to ten years): wind mills -  highly dependent on local opinion